Evaluation of Laser Rangefinders

U.S.Department of Agriculture Forest Service National Technology & Development Program 2000—Inventory & Monitoring 1019 1803—SDTDC April 2010 EST SERVICE FOR Evaluation of Laser Rangefinders A RT MENT OF AGRIC U L T UR E DE P WEB ONLY Evaluation of Laser Rangefinders by Reynaud Farve U.S. Forest Service San Dimas Technology & Development Center April 2010 Information contained in this document has been developed for the guidance of employees of the U.S. Department of Agriculture (USDA) Forest Service, its contractors, and cooperating Federal and State agencies. The USDA Forest Service assumes no responsibility for the interpretation or use of this information by other than its own employees. The use of trade, firm, or corporation names is for the information and convenience of the reader. Such use does not constitute an official evaluation, conclusion, recommendation, endorsement, or approval of any product or service to the exclusion of others that may be suitable. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. Background BACKGROUND The proposal for an updated rangefinder evaluation was submitted by the Chattahoochee-Oconee National Forest. They requested that the Technology and Development Program update the 1998 rangefinder evaluation (9824 1307—SDTDC). The Inventory and Monitoring Steering Committee directed San Dimas Technology and Development Center (SDTDC) of the Forest Service, U.S. Department of Agriculture, to conduct the new evaluation in fiscal year 2009. Forest Management United States Department of Agriculture Forest Service Tech Tips Lois P. Sicking, Mechanical Engineer INTRODUCTION Rangefinders are used to measure distance in a variety of applications for various resource needs in the Forest Service. There are many different types of rangefinders commercially available. In addition, there have been recent advances in rangefinder technology. The cost of rangefinders varies from $60 to $12,000. Performance varies as much as cost. Significant factors in evaluating performance are range, accuracy, ease of use under field conditions, size and weight. The required accuracy will vary depending on the application or the task being performed. Typical applications include determining the distance to surrounding trees from a plot center, the distances from one fixed point to another as in traversing, and calculating tree heights. In addition, rangefinders can be used to help determine the volume of a specific tree or stands of timber. The current trend, in the USDA Forest Service and other agencies, is to use more tree measurement sales with lump sum payments. Consequently, it is imperative that the volumes stated in the contracts be very accurate. Some rangefinders are very accurate, lightweight and compact. Others are quite heavy and cumbersome. The size and weight of equipment carried in the field vest is a consideration for applications which entail walking long distances or on steep terrain. OBJECTIVE The objective of this test was to evaluate the performance of various rangefinder devices. The range, accuracy, size and weight of these devices were compared. In addition, test workers were surveyed for their opinion regarding ease of use. Comments were solicited on what effect the weather or other field conditions appeared to have on the readings. Additional performance features were noted. The project goal was to provide information to the Technology & Development Program February 1998 2400 9824 1307–SDTDC RANGEFINDER COMPARISON field on the performance of various laser, ultrasonic and other current rangefinder devices. There is potential for considerable cost savings for field personnel using this information when selecting the appropriate rangefinder for the application. RANGEFINDER TECHNOLOGIES Ultrasonic Ultrasonic distance measuring devices use a wide band frequency from a transducer, sending out narrow beams of sound waves which “bounce” off an object. The return signal is picked up by a hand held receiver. Accuracy is effected by the position of the receiver, outside sound waves, and noise. Noise generated by wind through the trees or brush, streams, rain, crew talking, road traffic or birds chirping can effect readings. When a horizontal distance measurement is being taken, the inclination or horizontal position of the receiver is critical. An outgoing wide band signal will be scattered, increasing the error, if the transducer is not positioned as close to horizontal as possible. Optical Optical distance measuring devices typically use the coincidence method of determining distance. This incorporates the use of a series of lenses and mirrors to produce a double image. The double images on mirrors are brought together by rotating a dial until both images merge into one. The dial has a distance indicator, when the two images merge, the distance to the target is read directly off the dial. Laser Pulse lasers determine distance by measuring the amount of time required for a pulse of infrared light to travel to the target and back. The speed of light is constant, so this amount of time is directly proportional to the distance. Many pulses are sent out and returned for each shot, improving the accuracy of the calculated value. Laser instruments are narrow band and require the operator to aim with some For additional Information contact: Forest Management Program Leader, San Dimas Technology & DevelopmentCenter, 1 444 East Bonita Avenue, San Dimas, CA 91773-3198 Phone: 909-599-1267; FTS: 700-793-8000; FAX: 909-592-2309; DG—SDTDC: WO7A; IBM: Mailroom/wo,sdtdc FS web: http://fsweb.sdtdc,wo,fs,fed,us E-mail: Mailroom/[email protected] Figure 1—1998 Rangefinder comparison study (9824 1307—SDTDC). The Forest Management Steering Committee was also interested in the results of the rangefinder evaluation. They requested that the evaluation make a concerted effort to test a rangefinder’s ability to take accurate horizontal distance measurements through dense brush. The steering committee also was interested in having SDTDC evaluate a specific rangefinder, the Opti-Logic. (This rangefinder commonly is used by foresters.) 1 modern rangefinder devices transmit a pulse laser beam that strikes a target. optical devices (coincidence rangefinders) used a system of lenses. the more likely the beam reflects properly back to the device.) Figure 2— Laser rangefinders transmit pulsed laser beams through the transmitter lens. Other modern devices use the time of flight of ultrasound to calculate distance. which was attached to the target to capture the device’s incoming ultrasonic beam and return an ultrasonic response to the device. The distance between the rangefinder and target is calculated based on the time of flight of beams. Historically. (Obviously. especially when using the narrow laser beam. which in turn. Typically. Both laser and ultrasonic devices must be aimed with some accuracy to strike the intended target properly. This is usually not an issue when the target is a large tree trunk.) The device uses time of flight of a beam to reach a target and bounce back to calculate the distance. mirrors. But obtaining distance to smaller (narrower) targets requires more careful aim.Evaluation of Laser Rangefinders Rangefinders A rangefinder measures the distance from the device to a target. and trigonometric relationships to determine distances. the more reflective the target. 2 . Laser and ultrasonic rangefinders have largely replaced that technology. (Note: the ultrasonic rangefinder tested in this evaluation utilized a transponder (transmitter and responder). is reflected back to the device’s receiver lens. the target reflects beams back to the receiver lens. com) of MDL/Western Data Systems. 1 SDTDC thanks Russell Bozeman (russell. Inc. laser rangefinders have an advantage over sounddriven devices because light can travel farther (take longer measurements). Michael Hefer ([email protected]) of Leica Geosystems. HD measurements were taken through dense brush to test the rangefinders’ ability to take precise and accurate measurements. In addition. Also. and Tim Commons (tim. DEVICES TESTED Several rangefinders were evaluated for their precision and accuracy in taking horizontal distance (HD) measurements— at various distances—to an unobstructed target in a manner similar to the 1998 report. SDTDC tested the devices for this capability.commons@leicaus. SDTDC asked several rangefinder manufacturers if they would be interested in loaning the technology and development staff devices to be tested.bozeman@haglofinc.) During the spring of 2009.com) of Haglof. since all devices tested purported to operate as a hypsometer (a device that can measure the height of objects). for the loan of the devices. especially for their precision and accuracy in taking HD measurements1 . Inc.Devices Tested In general. Joe Cronn (jcronn@lasertech. ultrasonic devices benefit from the use of the transponder on the target. Both noise and temperature can affect measurements made by ultrasonic devices. 3 . Since the Forest Management Steering Committee was specifically interested in devices capable of making precise and accurate measurements through dense vegetation. When measuring through dense vegetation. Laser rangefinders use reflectors and foliage filters to take accurate measurements in dense vegetation (see Devices Tested for a detailed discussion). Table 1 lists the devices SDTDC tested for this evaluation. (Instances where this evaluation deviates from the previous report are identified in this evaluation. SDTDC also performed a cursory test of this capability.com) of Laser Technology. and light is essentially unaffected by temperature and not affected by background noise. cost** $2. opti-logic. leica-geosystems.com Approx. The precision and accuracy evaluation of the devices are in the Results section. Inc.Evaluation of Laser Rangefinders Table 1.com haglofsweden. the user could look into the device’s viewfinder for some instruments (to view the information) and/or view the information from a display window on the side of the device.500 $1. All came with a convenient protective carrying case that could be clipped on to a belt buckle or carried easily in a field vest or backpack. Devices SDTDC tested for this evaluation.900 TruPulse Laser Technology.700 (360B) $2. users should plan on spending some time reviewing the entire manual and practicing navigating through the various features of the devices to get the maximum out of the various features that the devices have to offer.com (200B and 360B) LaserAce (2D and 3D) Leica Disto D8 Opti-Logic 1000LH Measurement Devices laserace. 4 . The user manuals for all devices were straightforward to follow. When using the devices. Device Manufacturer* Web site Vertex Laser VL400 Vertex IV (ultrasonic) Haglof Sweden Haglof Sweden haglofsweden.com $800 (200B) $1. navigating to the various features was more or less intuitive.com Limited (MDL) Leica Geosystems. Inc. rangefinder technology has advanced such that all devices SDTDC staff tested were lightweight and fit easily in the palm of the hand. **cost as of 2009 The following is a brief description of the devices. however.800 (3D) $800 $550 * see footnote 1. When a device took a measurement. Since the 1998 report. In all cases.200 (2D) $2. lasertech. All devices operated on either regular alkaline batteries or a specialized rechargeable battery pack provided with the device.com Opti-Logic Corp. 7 inches by 2.8 inches by 2. Dimensions: 3. 5 . With the press of a few buttons. The USA headquarters is in Madison. even in bright sunlight. Dimensions: 3.Devices Tested Vertex IV and Vertex Laser VL400 (Vertex IV—Weight: 6 ounces. The users (sic) guide is fairly straightforward. The Vertex IV (figure 3) takes measurements by ultrasound only.1 inches) (Vertex Laser VL400—Weight: 9 ounces. The viewfinder had both 1x and 8x magnification. The Vertex Laser VL400 (figure 4) is a combination laser and ultrasonic rangefinder. The text characters are bold and clear and relatively easy to read.1 inches by 2 inches by 1. Figure 3—Vertex IV Rangefinder (ultrasonic only) Figure 4—Vertex Laser VL400 (laser and ultrasound).3 inches) Both Vertex devices are products of Haglof Sweden. measurements could be taken and viewed through the lens and the display window on the side of the device. MS. which provided clear viewing of targets near and far. The B versions of the devices (200B and 360B) allow for wireless transfer of data to a field data recorder. a transponder must be placed on the target. the transponder will emit a signal to the rangefinder only if it receives a signal from the rangefinder. 6 . For more details on devices. Centennial. and adjustable eyepiece made viewing through the lens simple. Click here for the Vertex Laser VL400 Users Guide . CO. The device is operated by a few buttons on the side.Evaluation of Laser Rangefinders The main advantage of using ultrasound is being able to take measurements through a dense understory. This ensures that the signal that returns to the device is from the target (transponder) and not from understory vegetation between the target and device. Sending and receiving sound is significantly distance limited. see the users guide. TruPulse 200B and 360B (Weight: 8 ounces.English. The user must look through the viewfinder to operate the device. Testers were amazed that the through-the-lens-only viewing was not a disadvantage when compared to devices with a side window display. In this way. Figure 5—TruPulse laser rangefinders. The clear optics. Click here for the Vertex IV Users Guide .5 inches) The TruPulse laser rangefinder (figure 5) is a product of Laser Technology. To take accurate ultrasonic measurements. Dimensions: 5 inches by 2 inches by 3..English. 7x magnification. accurate measurements are obtained only within 100 or 150 feet from the target. Inc. 7 . but also obtain the distance between the two targets by using the device’s missing line feature. (Note: the LaserAce 3D uses its missing distance feature to measure distances between two objects. page 37). the boxy looking text was a nonissue. Figure 6—Sample view in TruPulse viewfinder. The difference between the TruPulse 200 and the TruPulse 360 is the integrated compass of the 360. it can operate in three dimensions.Devices Tested Initially. A user can stand in one spot and not only take an HD measurement to two targets. Once the device is calibrated. the block text characters in the viewfinder took some getting used to.) Figure 7—Determining the horizontal distance (HD) between two targets (missing line) using the TruPulse 360 (from the user manual. But after several minutes of use. S.Evaluation of Laser Rangefinders The manufacturer also markets the TruPulse as a device that can take accurate measurements in the field even in areas where there is a dense understory. When the device is in the farthest-target mode. For more details on the TruPulse laser rangefinder see the Laser Technology. which like the TruPulse 360 allows it to operate in three dimensions. the device has features that assist in distinguishing the understory from the intended target. 8 . laser beams reflected from the understory vegetation will not be registered and the only reading identified by the device will be from the intended (highly reflective) target. one would use the device in the farthest/closest or filter-target modes.3 inches by 2. Dimensions: 4. the user ignores readings that were taken when striking foliage between the observer and the intended target. The reader might also be interested in reviewing the evaluation of the TruPulse 360 reported in the March 2009 issue of The Forestry Source.A. Inc. The U. The reverse is true when the device is used in the closesttarget mode.9 inches by 2 inches) The LaserAce rangefinder is a product of Measurement Devices Ltd. The filter reduces the receiving lens’ sensitivity to a point where it will only detect pulses returned from a highly reflective target (the reflector). The 3D model has an integrated compass. if the target is partially visible (capable of being hit by a narrow beam). LaserAce 2D and 3D (Weight: 14 ounces. Even though the laser beam cannot penetrate the understory. TX. when used in this manner. The LaserAce 2D and 3D both have Bluetooth capability. Scotland. the device will show the readings of the farthest target it acquired (and hide the readings of the closer targets acquired) while laser beams were pulsed. To accomplish this. The most reliable (and accurate) method of obtaining distance measurements through a dense understory is to use a foliage filter and a reflector. In that way. headquarters (Western Data Systems) is in Houston. Obviously. (MDL) of Aberdeen. Web site. This involves placing a reflector on the target and attaching a specialized foliage filter to the rangefinder’s receiving lens. much like the other rangefinders tested. Figure 9—Close up of side display window. 9 . Measurements can be viewed in the viewfinder and on the side window display. The calibrated 3D device operates much like the TruPulse 360. The viewfinder has 5x optics and clear crosshairs that allow targets to be acquired easily.Devices Tested Figure 8—LaserAce rangefinder with carrying case. The LaserAce operates with a few buttons on the side of the device. It allows the user to stand in one spot and take the HD measurements between the two distant objects using its missingdistance feature. Gallen.. The device’s lasthit mode operates like TruPulse’s farthest-line function. The U. The D8 has Bluetooth capability.) The LaserAce also operates in a brush-filter mode much like TruPulse’s foliage-filter mode. For more details on the LaserAce laser rangefinder see the MDL Web site. the user acquires the target by aiming the visible red laser beam dot onto the intended target.A.2 inches by 1. . 10 Figure 10—Disto D8 showing display screen in viewfinder mode (left) and normal mode (right). The difference is that the manufacturer suggests that a 3M reflector foil be used (instead of a prism reflector) on the target and that this mode should not be used at distances less than 100 meters (328 feet).6 inches by 2. headquarters is in Norcross. the device is advertised as being able to take accurate measurements through dense brush. GA. Leica Disto D8 (Weight: 6. There is no eyepiece to view the target.Evaluation of Laser Rangefinders Like the TruPulse. The D8 is marketed primarily for use on construction sites and can operate like an electronic tape measure.2 inches) The Leica Disto D8 is a product of Leica Geosystems. Switzerland. St.9 ounces. Alternatively. (The first-hit function is its opposite. The D8 was the most unique rangefinder device tested. Dimensions: 5.S. Inc. The D8 is advertised as being accurate to ±1 millimeter. rather the target is displayed and acquired by viewing the display window. the device had many features that might be useful at a construction site that some users (especially engineers) might find valuable. But even with those features. This was especially true when the observer was in bright sunlight and the target was in dense shade.Devices Tested In an indoor setting at a construction site.) 11 . and 1000LH). Dimensions: 1. the 400LH model operates up to 400 yards. For more details on the Leica Disto D8 laser rangefinder. etc. see the Disto D8 Web site or download the brochure or user manual. The product comes in a series of models (100LH. testers found it difficult to acquire targets on our test course that were more than 60 feet away. acquiring a target is not a problem. Figure 11—Measurements that the D8 is capable of taking at construction sites. Opti-Logic 1000LH (Weight: 11 ounces. of Tullahoma. is a challenge.1 inches) The Opti-Logic rangefinder is a product of Opti-Logic Corporation. This greatly improves visibility outdoors. (For example.) Despite the Disto D8’s limitations of taking long HD measurements in a forest setting. 400LH. 800LH. which have varying operational distance ranges. the 100LH model can take accurate measurements up to 100 yards.7 inches by 4 inches by 5. Acquiring targets outdoors. however. TN. The device has a digital pointfinder mode that shows the target as crosshairs on the display window and has 3x magnification capability. The device was the least expensive of the true field laser rangefinders that we tested. 600LH. (See a more detailed discussion of the limitations of the device as a practical field tool for taking HD measurements in the Results section. 2-inch by 0. When you turn it back on. Figure 12— Opti-Logic laser rangefinder. and the vertical angle to an object measurements. The target is acquired by sighting through the eyepiece (which has no magnification power) and using the red dot in the viewfinder to aim at the target. you must click through the options (using the only top button) to find the new setting. To change a setting. The reader might be interested in reviewing the evaluation of the Opti-Logic in the June 2009 issue of The Forestry Source. this device has far fewer features than the other devices tested. For more details on the Opti-Logic laser rangefinder see the company’s Web site. front view. To scroll through the device’s features can be cumbersome. The device’s only button on the top of the device fires the laser after the button is released. Measurements are read in the display window on a 1. The operating instructions are on only 2 pages. 12 .Evaluation of Laser Rangefinders As suggested by the price. Insert on top is a rear view that shows the display window (right) and viewfinder (left). the new setting is available. The device takes only line-ofsight distances.5-inch screen next to the eyepiece. horizontal distances. height of an object. and then allow the device to turn itself off. Figure 13—View of the SDTDC woodlot from the lower end of the transect. facing northeast. we tested the Opti-Logic rangefinder in October 2009.7-acre) woodlot on the SDTDC property. 13 . We evaluated five devices during the summer of 2009. Three SDTDC employees took the measurements reported in this evaluation. Figure 14—View of the SDTDC woodlot from the center of the transect.Test Course TEST COURSE HD Measurement on Test Course SDTDC staff (we) evaluated the six rangefinders on a 220-foot by 330-foot (1. The SDTDC woodlot is composed of scattered locust trees with occasional evergreens and oaks. facing northeast. especially when compared to the effort that is likely to be expended by the average field person to determine distance from a target. (Note: the 1998 report tested rangefinders up to a distance of 500 feet.5 feet above the ground. used an electronic distance measuring (EDM) infrared rangefinder to establish the true distance. Figure 15—Target tree and target (Smokey Bear bookmark). which was a locust tree in one corner of the woodlot. then continuing at 25-foot increments up to 300 feet.) We located stakes by stretching a 300-foot fiberglass tape as taut as possible and using a plumb bob to mark the location. however. 14 . The target is about 4. We decided to use the distance measured by a tape (instead of an EDM rangefinder) as the true measure of distance because we felt that the evaluation was a test of how accurate and precise rangefinders were when compared to the tool normally used for HD measurements. The longest diagonal length on the woodlot with an unobstructed view to a target was only 300 feet. The 1998 report. We felt we established a reasonable true distance from the target. The total course length was 300 feet with stakes placed every 10 feet.Evaluation of Laser Rangefinders The test course consisted of a series of stakes that marked the distance from an unobstructed target. a measurement tape. up to 100 feet. The more advanced features of the devices took more time and practice. repeatable measurements. farthest/nearest line.Test Course Figure 16— An observer taking a measurement at 70 feet from the target. and within a few minutes each observer could take reliable. Typically. (See the discussion of rangefinders: missing line. One of the observers became an expert on the use of the rangefinders by studying the user manual and practicing with the device before the day of the test. tree height. The simple measurement of HD was fairly straightforward for all devices. The usual process involved an observer taking 12 measurements at a given distance and then passing the 15 .) Each of the observers took 12 measurements at each distance. and foliage-filter features. all three observers took measurements on the same day of the test. That observer instructed the other two users on the use of the rangefinders. Evaluation of Laser Rangefinders device to the next observer who took 12 measurements at that distance. HD Measurements Through Brush Several rangefinders were tested for their ability to take HD measurements 80 feet from a target that was obscured with a dense understory of brush. We tested all rangefinders without a tripod (hand held) and only with fresh batteries (as was done in 1998). While one observer took measurements. (We estimated that the target was about 80 percent covered. Observers took measurements in no particular order. The second observer then passed the device to the third observer. None of the three observers wore hardhats or gloves. one of the other two observers manually recorded information on a data sheet. an observer was unavailable on a given day or time.) Figure 17— Observer sighting on a target tree 80 feet away with dense brush obstructing view. 16 . unlike 1998. On a rare occasion. the single observer took solitary measurements when he/she was available. in that instance. We used a simple red reflector attached to a target tree for the foliage-filter test of HD. and Vertex Laser because their manufacturers’ claimed that the devices could be used for taking measurements through dense vegetation. LaserAce. we only tested the last-hit feature. We tested the TruPulse. 17 . we tested the foliage filters and farthest-line/nearestline features. In this same dense brush location. Since we did not have foliage filters for the Laser Ace. For the TruPulse. we tested the ultrasonic ability of the Vertex Laser to take HD measurements. which is similar to TruPulse’s farthestline feature.Test Course Figure 18— Closeup view of the target tree (with reflector). Evaluation of Laser Rangefinders Distance Between Two Objects and Height of Object Tests We tested the LaserAce 3D and the TruPulse 360’s ability to take measurements between two objects (trees). Since this was not the primary objective of the evaluation. tree A and B. we only took a few measurements to sense the accuracy and precision of the devices. We also took simple height measurements of a fence post supporting a chain-link fence with the all-laser devices. Figure 19— Distance measurement between two objects. 18 . but overall the testers were impressed. All devices we tested were reasonably sturdy. We used the standard deviation of the 12 readings to demonstrate the precision (repeatability) of the device in taking HD measurements. all devices were relatively easy to operate. long-distance measurements. we compared the average of the 12 readings against the true measurement obtained with a fiberglass tape measure. All observers felt that using a tripod would produce more accurate and precise HD measurements from any of the devices tested. 12 readings were taken by 3 different observers. At those distances it is much more difficult to site the target and maintain a steady aim using the devices in hand-held mode.Results RESULTS Rangefinder Horizontal Distance (HD) Measurements The test results for the six different rangefinders are shown below. For users that require accurate. In general. This was especially true the further the user moved from the target (more than 200 feet). For an accuracy determination. and came with a canvas field case that would be very easy to pack in a vest or backpack. As might be expected. 19 . regardless of the manufacturer. Most devices were more accurate at distances less than 200 feet when compared to their accuracy at 300 feet. a tripod is a must for any rangefinder. lightweight. the more expensive devices tended to be more accurate and precise. As mentioned previously. Each device has slightly different features or means of operating. It bears repeating that we took measurements with the devices hand held. 1 Avg = average.0 0. The data shows that at further distances (more than 200 feet) the device was less accurate.0 CNG *** *** *** -0.5 0. Table 2—Combined readings (in feet) from the Vertex Laser (VL400) in laser mode Station 10 20 30 40 50 60 70 80 90 100 125 150 175 200 225 250 275 300 AVG *** *** *** 39.5 80.8 0.6 202.2 1.2 252.5 126.8 1.3 60. the same is true for the accuracy of the device.6 304.2 0. The device does not take measurements under 31 feet.0 0.3 151.1 TOTAL (all observers) DEV *** *** *** 0.1 0.5 1.8 2.5 1.6 227.4 0.5 2.6 4.2 90.6 -0.2 0.5 277.0 0. In general.5 0.6 2. Table 2 combines the readings of the three observers. and were slightly less precise at further distances.1 70. the measurements are highly precise (repeatable).4 0.7 0.8 0.3 0.0 175. Cng = average minus station 20 .Evaluation of Laser Rangefinders Vertex Laser VL400 (laser mode) The results of the HD measurements of each of the three observers can be viewed at the following link—Vertex Laser VL400.0 0.3 1.6 2.4 49. Dev = standard deviation.2 2. At distances less than 150 feet.2 100.7 0. 1 0.1 -0. we could not get a reading when using the ultrasonic mode.1 -0.0 70.0 0. The user does not need to aim and sight on the target carefully.3 -0.7 Avg = average.1 0. Beyond 125 feet.Results Vertex Laser VL400 (ultrasound mode) The results of the HD measurements of each of the three observers can be viewed by following the link—Vertex Laser VL400 (ultrasound).0 79. Table 3 combines the ultrasonic readings of all three observers. Dev = standard deviation.2 0. observer #1 The Vertex Laser was unique in that it could take measurements using either a laser or ultrasound.9 29.9 125. and press the power button to get highly accurate readings.1 0. (The transponder was attached to the target tree to take the ultrasonic HD measurements. Nevertheless. the results show that this device is highly precise and accurate up to 100 feet. point the rangefinder at the target (transponder).1 0.7 TOTAL (all observers) DEV 0.1 CNG -0.9 40.2 0. You simply hold the device sideways (to view the side display window).2 0. Our test confirmed that limitation.2 0.3 0.7 89.0 50.0 0.1 60. Table 3—Combined readings (in feet) from the Vertex Laser VL400 in ultrasound mode Station 10 20 30 40 50 60 70 80 90 100 125 AVG 9.2 0.9 19.1 0. Cng = average minus station 21 .8 99. Using the device (with the transponder) in this mode is very easy and largely foolproof.0 -0.2 -0.1 0.1 0.) The manufacturer’s specification identified that the device’s ultrasonic accuracy is limited to about 100 feet. 9 41. Again.1 0. we could not get a reading.3 0.Evaluation of Laser Rangefinders Vertex IV (ultrasound) The results of the HD measurements of each of the three observers can be viewed by following the link—Vertex IV (ultrasound) This device only takes ultrasonic measurements.0 1.4 0.1 0.6 71.9 82.6 1. Since the other Haglof product (Vertex Laser VL400) performed so well in the ultrasonic mode.2 1. the accuracy was outside the manufacturer’s predictions (greater than 1 percent).2 *** CNG 0. Table 4 combines the ultrasonic readings of all three observers. we suspected that the device that we tested might have been defective. the Vertex IV was very easy to use and taking measurements was relatively foolproof.3 *** Avg = average. the manufacturer’s specification identifies that the device’s ultrasonic accuracy is limited to about 100 feet.1 0.6 103.1 0. our test confirmed that limitation. Table 4—Combined ultrasound readings (in feet) for the Vertex IV Station 10 20 30 40 50 60 70 80 90 100 125 AVG 10. Cng = average minus station 22 .2 2.1 0.9 1.2 0.2 92.6 3.4 30.3 0. At all distances except 10 feet. As with the Vertex Laser VL400. As with the Vertex Laser VL400 in ultrasonic mode.1 0.3 *** TOTAL (all observers) DEV 0. Dev = standard deviation.2 61.0 51.9 2.1 0.1 20. We found that the Vertex IV was as precise (gave repeatable measurements) as the Vertex Laser VL400 but were surprised that it was not as accurate. Beyond 100 feet. 3 -0.3 -0.6 0. and 300 feet) using the TruPulse 360B and found it to be as accurate and precise as the TruPulse 200B for HD measurements. the data shows that at further distances (more than 200 feet) the device is less accurate.4 0.1 TOTAL (all observers) DEV 0. Cng = average minus station . We took several measurements (12 for each observer) at several distances (50.3 0.1 1.5 0.6 174. At distances less than 250 feet.5 -0.4 -0. measurements are very precise (repeatable). As reported for the other devices.3 1.0 49.6 19.3 -0. Over the entire 300-foot test course.4 124.3 0.6 59.6 0. Table 5—Combined readings (in feet) for all observers using the TruPulse (200B) Station 10 20 30 40 50 60 70 80 90 100 125 150 175 200 225 250 275 300 AVG 9.5 0.1 0.2 0.8 226.8 1.2 0.0 -0.4 2.3 0. 100.6 200.2 0.0 CNG -0. the TruPulse 200B was within the accuracy claimed by the manufacturer of ±3 feet for low-quality (nonreflective) targets.4 277.4 -0.8 149.Results TruPulse 200B (and 360B) The results of the HD measurements for each of the three observers can be viewed by following the link—TruPulse Table 5 combines the readings of all three observers using the TruPulse 200B.8 1.6 -0.3 2.2 0.5 79.5 99.4 0.5 -0.8 40.4 -0.1 23 Avg = average.1 251.2 0.7 29.3 302. Dev = standard deviation. 200.3 0.7 69.0 0.3 89.7 -0. The device maintained high accuracy at all distances.Evaluation of Laser Rangefinders LaserAce 2D and 3D The results of the HD measurements of each of the three observers can be viewed by following the link—LaserAce Table 6 combines the readings of all three observers for the LaserAce.0 60. the LaserAce was the most accurate field device tested.1 -0. 100. Dev = standard deviation.3 -0.8 50. Over the entire 300-foot test course.1 69.2 0. (The LaserAce was the most expensive device tested.3 0.9 0.1 150.0 300.2 0.5 Avg = average.3 1.) We took several measurements (12 for each observer) at several distances (50.7 0.2 -0.7 19.2 0.1 1.9 5.8 79. and 300 feet) using the LaserAce 2D and found it to be as accurate and precise as the LaserAce 3D for HD measurements.7 99.3 0.7 0.3 0.3 201.3 -0.0 0.7 125.3 0. the device was within the ±0.2 0.4 inches) accuracy claimed by the manufacturer.3 0.2 -0.5 CNG -0.5 0. Cng = average minus station 24 .7 225.3 3. measurements are very precise (repeatable).9 39.2 0. On 10 of the 18 measurements taken on the test course.1 0.2 -0.2 275.3 175. At distances of less than 150 feet.8 89. Table 6—Combined readings (in feet) for all observers for LaserAce (3D) Station 10 20 30 40 50 60 70 80 90 100 125 150 175 200 225 250 275 300 AVG 9. 200.7 0.4 1.2 0.9 250.2 0.2 0.3 1.8 29.5 TOTAL (all observers) DEV 0.2 foot (2.0 0.1 -0. 1 0.1 0.1 -0.1 0.3 40. rather the target is displayed and acquired by viewing the display window.2 0. especially in bright sunlight.3 0.6 TOTAL (all observers) DEV 0. Cng = average minus station The device is not marketed for field forestry use but may be of value at construction sites.3 0.1 70. Dev = standard deviation.1 0.3 0. As stated previously (in the Devices Tested section).3 0.2 0. but if the target is in dense shade and the viewer in bright sunlight detecting the target is still very difficult. and the test was terminated.Results Leica Disto D8 The results of the HD measurements of each of the three observers can be viewed by following the link—Lecia Disto D8 Table 7 combines the readings of all three observers using the Leica Disto D8.2 0.1 80. our data shows that the D8 is extremely accurate (although not as accurate [±1 millimeter] as the manufacturer claims).8 99.4 0.3 0. Table 7—Combined readings (in feet) of all three observers for the Disto D8 Station 10 20 30 40 50 60 70 80 90 100 AVG 9.2 50.3 0. the device never differed from the true (tape measured) distance by more than a few inches.4 Avg = average.7 CNG -0. We found that even hand held. after 100 feet it became very time consuming and difficult to acquire the target.9 20.0 60.1 89. Viewing targets outdoors. is very difficult at distances greater than 60 feet. Despite this limitation.0 0.0 30.2 -0. Even though the manufacturer claims that the device takes accurate measurements as far as 328 feet (100 meters). 25 . the D8 has no eyepiece to view the target.0 0. The device’s digital pointfinder helped somewhat. 1 1.8 82. This device offers a no-frills alternative for a laser rangefinder.1 2.9 51.9 1.8 127.6 1.5 0. especially for users that do not require high-accuracy measurements. the device met the manufacturer's claim of measurement accuracy to dark targets (±6 feet).9 CNG Station 10 20 30 40 50 60 70 80 90 100 125 150 175 200 225 250 275 300 AVG 21.5 0.9 176.7 62.6 0. Table 8—Combined readings (in feet) of the three observers for the Opti-Logic LH1000 26 TOTAL (all observers) DEV 0.7 0. It also was the least precise and accurate. The Opti-Logic was the least expensive of the field rangefinders tested. Nevertheless.Evaluation of Laser Rangefinders Opti-Logic 1000LH The results of the HD measurements for each of the three observers can be viewed by following the link—Opti-Logic 1000LH Table 8 combines the readings of all three observers for the OptiLogic LH1000.7 227.8 4.1 1.0 1.3 101.9 253.3 1.1 0.9 40.1 71.9 1.6 1.0 91.6 0.0 1.8 3.1 30.8 2.8 2.0 0. Dev = standard deviation.9 0.1 1.7 2.9 Avg = average.5 0.3 2.6 0.2 3. Cng = average minus station .8 279.8 203.3 152.0 1.9 3.4 2.6 0.2 303.7 2. 0 1.2 277.6 277.5 0.7 100.2 80.4 100.3 126.3 126.7 90.5 2.1 101.8 0.3 150.0 0.2 277.5 49.8 226.9 150.6 252.4 39.5 175.1 126.6 0.4 39.6 278.5 201.6 2.8 202.7 60.8 0.7 60.8 201.4 49.4 252.0 126.7 0.4 39.4 252.2 49.5 60.7 70.7 70.7 0.311 feet.2 277.7 100.4 303.4 252.9 175.6 252.4 49.4 39.2 277.3 0.6 *** *** *** *** *** *** 0.2 49.5 175.4 39.5 301.3 126.8 303.0 0.5 226.0 0.3 150.9 175.2 90.4 80.7 60.4 0.2 39.4 226.5 80.4 90.3 150.5 80. Range of meter's ability to take accurate measurements (per manufacturer) = 31.9 150.Tables 9 through 29 show the measurements taken by each of the three observers for the seven devices.4 90 90.7 60.2 1.6 259. .9 175 175.4 228 126.2 90.5 80.7 175.3 126.3 150.9 175.7 60.0 -0.3 150.2 301.2 300 303.7 100.2 90.7 252.8 201.9 303.5 70.6 250.7 101.9 175.4 80.8 226.4 226.7 101.8 201.3 126.4 80.4 303.5 201.3 126.4 80.2 60.9 306.8 201.5 70.0 0.4 226.4 226.5 1.5 80 80.2 60.9 0.4 303.5 201.9 150.4 90.5 feet to 1.6 253.3 226.7 3.6 2 3 4 STAT1 1 10 too close 39.7 70.1 277.4 90.2 49.2 90.3 0.7 60.4 80.4 49.2 101.5 200 201.5 80.5 70.8 1.4 39.4 90.7 60.5 175.3 150.0 277.9 277.2 49.5 203.2 101.6 303.8 208.4 226.3 150.7 70 70.7 70.2 90.5 175.1 126.0 0.2 feet for distances less than 300 feet and ± 3 feet for distances greater than 300 feet.4 50 49.4 80.8 201. 3 Change = Average distance recorded with rangefinder minus measured distance.5 175.5 175.2 39.4 20 too close 30 too close 40 39.6 277.0 1.5 70.0 -0.7 126.3 126.2 60.7 70.4 80.0 2.4 228 252. observer #1 5 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 *** *** *** 39.5 175.0 0.8 303.4 39.3 150.4 90.2 70.2 49.9 275 278.1 101.2 60 60.2 277. Manufacturer's claim of meter accuracy at distances = ± 1.8 49.5 201.4 90.5 70.8 226.2 101.6 0.2 49.4 250 252.2 100.3 150.1 125 126.3 150 150.2 49.6 252.6 3.9 301.4 1 2 Results 27 Station distance measured with a 300-foot fiberglass tape.2 278.4 39.2 100 101. Table 9—Vertex Laser VL400.2 60.2 306.6 252.8 225 226.5 70. 5 303.1 49.8 201.5 59.9 150.5 175.9 49.8 301.1 228 251 277.1 100.4 90 90.2 50.2 100.4 39.1 59.5 70.4 250 251 251 275 277.2 278.1 98.6 150.5 0.7 59.3 150 152.0 0.6 254.4 78.9 151.4 0.2 278.1 100.5 70.4 78.2 300 301.6 0.8 226.4 20 too close 30 too close 40 39.0 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 *** *** *** *** *** *** 0.Evaluation of Laser Rangefinders 28 Table 10—Vertex Laser VL400.8 201.2 90.3 126.9 303.9 150.5 feet to 1.4 49.9 301.5 177.2 0.4 203.9 228 226.2 49.9 175 175.3 1.5 70.2 60 60.7 80.2 60.7 60.6 226.3 126.4 252.6 150.5 126.4 201.4 228 150.1 126.6 2.3 126.8 0.5 303.3 126.2 277.0 90.2 2.5 175.6 3.2 feet for distances less than 300 feet and ± 3 feet for distances greater than 300 feet.0 0.2 39.4 50 49.6 303.4 80.4 39.5 70.4 39.5 80.3 90.5 1 Station distance measured with a 300-foot fiberglass tape.0 0.1 100.5 80.2 278.5 205.1 126.8 226.4 90.2 80.9 2.2 50.0 2 3 4 STAT1 1 10 too close 39.2 90.7 70.2 175.4 80.6 277.6 251 203.9 175. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 31.4 39.2 90.3 150.1 126.4 39.5 70.9 203.1 125 126.8 1.9 152.7 0.0 70.2 277.8 0.2 90.7 70 70.2 49.1 251 252.0 0. observer #2 5 *** *** *** 39.7 60.1 0.2 59.4 90.9 301.2 175.1 -0.6 251 277.2 175.9 175.7 -0. Manufacturer's claim of meter accuracy at distances = ± 1.4 227.8 201.7 59.2 100 100.4 202.7 80.2 277.5 70.2 177.0 0.5 78.1 70.2 49.4 49.8 226.0 1.4 39.2 49.4 251 257.8 1.5 70.7 60.9 49.4 228 252.3 126.4 39.1 39.5 201.9 175.2 100.9 150.2 0.3 126.5 306.311 feet.2 70.2 100.8 201.3 100.2 90.9 303.1 2.1 100.5 0.3 150.9 177.4 100.9 277. .4 225 228 226.8 2.3 252. 3 Change = Average distance recorded with rangefinder minus measured distance.4 226.4 39.5 175.5 70.2 301.5 201.3 126.4 80.1 60.2 90.9 277.9 303.1 60.7 90.2 301.5 80.2 49.5 80 80.5 0.9 150.3 150.0 0.5 60.2 277.1 100.0 126.5 200 203.4 90.1 100. 5 70.0 59. 3 Change = Average distance recorded with rangefinder minus measured distance.8 205.3 126.Table 11—Vertex Laser VL400.3 126.4 308.4 90 90.2 49.6 252.1 300 306.1 306.5 306.5 252.4 39.9 0.2 0.1 228 227.7 308.5 0.4 90.5 278.5 1.5 59.2 101.8 303.2 0.3 126.3 128 150.5 70.9 175.4 80.1 125 126.1 100.1 60.1 303.4 39.5 2.3 150.3 126.2 59.5 feet to 1.5 70.2 feet for distances less than 300 feet and ± 3 feet for distances greater than 300 feet.9 150.5 203.6 1.3 0.6 252.5 80 80.5 78.6 252. Results 29 .2 49.3 126.6 150.2 201.8 175.6 1.3 126.3 150.4 80.1 100.4 225 228 228 250 251 252.8 303.7 150.4 306.6 0.5 175.9 252.4 228 228 228 150.5 90.9 175.1 70.9 175 177. observer #3 5 *** *** *** 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 *** *** *** 39.6 275 277.4 203.5 172.5 277.1 70.9 150.8 201.8 1.2 49.2 60 59.9 278.4 49.1 60.311 feet.6 -0.9 150.4 228 252.2 49.4 39.3 0.4 0.8 70.2 175.1 100.6 250.5 151.2 90.8 252.1 227.3 2.8 126.4 80.9 202.4 39. Manufacturer's claim of meter accuracy at distances = ± 1.5 70.5 200 203.9 150.2 100.7 126.5 277.7 49.2 101.4 70.9 252.2 90.3 0.6 277.2 175.4 39.7 226.5 70.4 228 228 252.4 0.8 201.1 59.5 70.0 0. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 31.9 2.3 1 Station distance measured with a 300-foot fiberglass tape.0 100.2 100 100.5 0.4 80.4 80.2 90.2 49.8 303.4 39.9 175.7 90.9 152.0 49.4 39.2 278.8 201.0 80.2 201.8 305.5 80.5 70.5 178.2 90.4 39.7 100.2 0.1 100.4 80.2 59.4 90.7 70.4 80.8 277.7 126.5 277.4 50 49.8 -0.2 90.1 101.2 49.6 277.1 70 70.7 5.6 0.7 60.8 228 252.2 49.9 177.7 59.2 80.3 100.7 126.9 175.7 0.5 172.4 0.8 2 3 4 STAT1 1 10 too close 39.5 80.2 49.5 201.6 2.3 150 150.0 0.4 39.1 101.1 126.4 20 too close 30 too close 40 39.7 60.4 49.5 203.1 59.2 90.3 90.2 39.1 278.2 90.1 306.1 277.8 201.1 59.4 1.9 *** *** *** -0.1 277.1 306. 1 30. .1 0.0 60.1 30.1 40.2 100.0 0.9 19.9 0.1 0.9 80 90 100.1 125.8 125.1 50.2 125.7 39.8 125.9 79.5 9.0 0.1 0.2 50.2 100.0 0.9 90 69.2 0.1 40 50.9 19.9 89.8 125.9 79.9 80 90 100.9 9.1 30.1 40.8 0.8 69.9 89.9 9.9 90 100.9 69.2 40 30.9 79.0 69.1 125.9 19.1 60.7 20 19.1 0.9 9.8 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.9 69.1 40.3 60.2 60 69.2 50.9 9. 3 Change = Average distance recorded with rangefinder minus measured distance.2 -0.1 0.8 50 50.9 9.1 -0.9 69.9 79.1 60.9 9.1 100.1 50.0 0.2 60 60 60 70 69.0 79.0 0.9 9.9 60.1 69.1 100.9 40 40 40.1 60.9 9.9 30.1 69.2 50.9 30 29.9 90 100.9 90 89.2 100.9 40 50.2 60.8 19.9 19.9 80 79.9 19.1 30.2 50.9 79.9 60.2 50.8 126 100.9 0. 2 Range of meter's ability to take accurate measurements (per manufacturer) = up to 100 feet.7 150 Beyond Range of Device 175 200 1 Station distance measured with a 300-foot fiberglass tape.9 90 79.1 30.9 89.1 30.2 60.7 125.1 40.9 79.9 9.1 126 125.9 89.8 19.1 100.1 30.9 100 100.1 40.1 125.8 10 9.Evaluation of Laser Rangefinders 30 Table 12—Vertex Laser VL400 (ultrasound).1 50.1 30. observer #1 5 9.2 50.2 100.1 50.7 29.1 90 79.9 69.9 79.2 0.1 -0.9 0.1 69.0 90.1 60.9 29.9 69.8 40 39.8 19. Manufacturer's claim of meter accuracy at distances is 1 percent or better.1 19.1 -0.0 0.4 19.7 125.9 19.1 2 3 4 STAT1 1 9.1 125 125.8 19. 9 70 69.8 70 59.1 30 30 39. 3 Change = Average distance recorded with rangefinder minus measured distance.8 19.9 10 9.8 100 100.8 79.2 0.0 59.1 100.9 39.1 100.9 0.8 59.9 89.1 125.1 89.9 19.8 100 100.7 89.8 19.9 19. Manufacturer's claim of meter accuracy at distances is 1 percent or better.8 0.9 29.2 30.8 10 9.6 125.9 50 50 50 50 50 59.7 125.9 50 50. observer #2 5 9.9 39.7 9.1 -0.9 50 59.8 0.0 69.8 90 89.0 0.1 60 59.9 80 79.Table 13—Vertex Laser VL400 (ultrasound).9 99.9 79.9 79. 2 Range of meter's ability to take accurate measurements (per manufacturer) = up to 100 feet.1 -0.6 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 9.5 89.8 79.5 30 30.9 50.1 125.9 69.9 100.9 50 59.9 69.1 30.7 30.8 79.9 100.0 0.1 100.0 -0.9 39.8 79.0 -0.9 39.8 20 19.9 50 59.8 9.9 59.5 19.1 30.9 50.9 89.8 0.8 39.1 0.8 79.1 -0.9 59.6 2 3 4 STAT1 1 9.2 -0.1 100.9 69.9 59. Results 31 .1 125.9 79.1 39.8 30.1 19.1 0.1 89.1 30.9 69.1 30.9 59.9 0.9 69.8 9.1 59.8 9.9 89.8 19.9 0.6 150 Beyond Range of Device 175 200 1 Station distance measured with a 300-foot fiberglass tape.9 39.8 125 125.8 89.2 39.1 39.8 19.0 0.7 89.9 69.7 9.8 125.6 125.2 99.9 79.7 125.6 69.0 0.1 125.7 19.8 19.2 39.9 69.1 39.8 89.7 30.9 79.2 -0.0 50.8 9.9 69.1 40 39.9 0.1 50.9 9.6 0.5 100 125.7 30.1 79.8 20.8 69.8 125.7 19.5 125.9 100.9 89.6 89.9 79. 4 0.0 0.2 20 19.2 79.4 89.4 70.0 0.1 60 60 60 70.4 125 125.4 89.1 10.Evaluation of Laser Rangefinders 32 Table 14—Vertex Laser VL400 (ultrasound).6 125.5 79.9 19.7 40 40 40 50 49.7 79.6 89.5 79.6 125.9 19.9 29.5 0.9 29.6 89.4 125.9 10.6 89.7 89.1 70.2 79.4 50 50 50 50 50 40.6 2 3 4 STAT1 1 10.0 60.6 0.0 79.1 10.1 60.4 125.1 70 70.2 -0.0 0. 2 Range of meter's ability to take accurate measurements (per manufacturer) = up to 100 feet.1 19.4 99.2 79.7 125.6 29.7 125.2 19.1 70.1 10.6 29.6 29.6 29.4 99.6 29.4 99.0 29.1 40.2 70.4 -0.7 89.6 89.6 40 50 60.6 99.0 0.0 50.6 19.1 0.1 70.1 40.2 60.2 10.4 79.6 0.9 70.6 99.6 29.6 40 50 60.1 10.1 70.6 99.1 0.6 150 Beyond Range of Device 175 200 1 Station distance measured with a 300-foot fiberglass tape.0 40.9 0.9 19.9 30 29.6 70.1 0.2 79.1 -0.1 10.5 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 10. .5 -0.1 99.9 10.9 19.0 19.7 89.9 29. 3 Change = Average distance recorded with rangefinder minus measured distance.4 0.2 79.4 89.4 125.5 89.6 125.2 80 79.2 60.7 125.5 99.1 10.9 19.1 70.1 19.6 0. observer #3 5 10.4 125.1 0.4 125.5 99. Manufacturer's claim of meter accuracy at distances is 1 percent or better.1 40 40 40 50 60.6 29.9 50 60 60 60.4 90 89.6 0.1 70.6 40 50 59.2 0.1 50 40 29.1 125.1 70.6 19.4 99.1 10 10.1 89.8 99.5 79.5 100 99.1 -0.6 99.9 19.4 79. 3 Change = Average distance recorded with rangefinder minus measured distance.4 1.4 92.5 103.5 92.1 61.6 61.0 0. observer #1 5 10.7 72 81.6 82 72 61.6 0.6 20.8 1.1 20.3 61.2 51.8 0.4 0.6 100 103.3 51.9 30.5 0.7 30.4 20.6 3.5 103.6 51.5 103.6 20.1 0.3 51.1 10 10 10 20 20.3 1.1 10.3 41.1 72. Results 33 .6 20.7 2.1 72 80 81.7 72 81.5 10.4 103.5 103.4 51.7 51.6 20.3 60 61.7 30.7 0.3 51.8 41.1 6 7 8 9 10 11 12 10.6 0. 2 Range of meter's ability to take accurate measurements (per manufacturer) = up to 100 feet.7 30. Manufacturer's claim of meter accuracy at distances is 1 percent or better.5 61.4 51.1 10.2 10.4 61.6 10.9 30.1 20.5 103.3 41.6 61.9 20.1 10.3 51.6 72 71.9 72 72 82 92.7 71.8 20.8 81.5 61.6 30.5 103.1 41.1 92.0 0.1 0.7 70 72.7 61.6 103.7 30 30.8 41.7 30.1 41.5 2 3 4 STAT1 1 10 20.3 51.7 92.1 82.9 92.4 51.3 30.9 90 92.8 40 41.9 82 92.3 0.9 30.6 20.8 30.9 92.6 103.4 41.2 41.6 0.1 30.5 41.5 61.1 20.0 2.9 92.Table 15—Vertex IV (ultrasound).8 72 82 92.1 10.9 41.5 92.7 103.0 0.9 41.3 50 51.6 82 82 82 92.6 103.1 103.5 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 10.4 61.0 2.8 72 81.6 61.2 41.1 51.5 30.5 125 Beyond Range of Device 150 1 Station distance measured with a 300-foot fiberglass tape. 9 10 6 7 8 9 10 11 12 10 20. observer #2 5 10.3 51.9 71.3 61.3 10. .4 61.1 0.1 92.4 10.6 30.2 20.7 61.7 72 82 92.0 0.2 10.4 125 Beyond Range of Device 150 1 Station distance measured with a 300-foot fiberglass tape.1 51.8 92.1 51.3 30.4 103.4 60 61.Evaluation of Laser Rangefinders 34 Table 16—Vertex IV (ultrasound).0 2.8 70 71.7 0.4 30.8 41 51.4 30 30.1 41.3 41 30.6 103.1 72 72 72 72 82. 2 Range of meter's ability to take accurate measurements (per manufacturer) = up to 100 feet.3 20.1 10.3 1.4 61.8 61.0 30.7 41.4 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 10.7 0.4 103.7 41.7 1.1 51.1 20.1 51.3 51.7 72 82 92.4 82.3 30.9 80 82 82.6 72 82.6 82 82 82.0 0.7 2.3 0.8 30.4 0.3 20.1 103.8 0.1 50 51.1 92.4 2 3 4 STAT1 1 10.7 20.7 72 82 92.8 103.3 0.3 20.1 72 61.1 92.7 30.3 20.3 61. Manufacturer's claim of meter accuracy at distances is 1 percent or better.8 92.1 1.3 103.1 0.7 51.8 51.3 20.1 90 92.7 100 103.7 30.8 61.1 72.1 20.4 103.3 0.7 30.3 41 41 41.6 103.1 41.3 51.1 20 20.8 41 51.1 10 10 10.0 0.8 71.4 20.1 0.7 92.4 10.8 40 41 41.8 20.7 61.3 30.0 2.0 82.4 103.1 41.3 61.9 82 92.8 103.1 9.4 103.6 92. 3 Change = Average distance recorded with rangefinder minus measured distance.4 92.3 51.8 30.0 61.7 3.3 61.6 103. 9 40.1 20.0 40.6 61.8 80 82.6 50.1 92.7 40.1 103.4 92.6 40.8 2.7 50.1 82.0 0.1 0.6 0.6 70 71. observer #3 5 9.6 61.7 103 82.6 40.8 1.3 31 40.6 40.5 30 31 30.0 0.1 10 10.9 10.5 82.8 82.0 0.5 71.0 0.1 10 10.3 6 7 8 9 10 11 12 10 20.8 61.1 103 92.6 100 103 103 125 Beyond Range of Device 150 1 Station distance measured with a 300-foot fiberglass tape.9 82.3 31 40.3 20.5 71.7 102.8 71.4 92. Manufacturer's claim of meter accuracy at distances is 1 percent or better.5 82.3 20.6 61.0 50.1 31.7 103 50. 2 Range of meter's ability to take accurate measurements (per manufacturer) = up to 100 feet.5 0.6 82.6 50.1 20.1 20 20.9 82.0 2 3 4 STAT1 1 10 20.3 31 40.6 40.5 92.6 61.5 90 92.5 71.7 50.6 0.8 0.5 71.0 71.5 2.6 61.5 1.3 1.5 0. Results 35 .7 71.9 82.8 71.3 61.6 50 51.5 61.6 31 20.9 82.4 92.6 50.5 71.7 50.6 103.3 30.0 0.6 31 31 31 31 31 20.7 103 92. 3 Change = Average distance recorded with rangefinder minus measured distance.3 0.Table 17—Vertex IV (ultrasound).9 40 40.6 102.5 20.7 61.6 50.6 40.9 71.3 20.1 103.9 10 10 10.6 40.9 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 10.5 61.9 0.7 3.7 0.5 50.1 10.5 71.4 92.1 103.3 9.5 50.8 82.5 92.7 92.9 61.9 102.5 92.7 82.9 20.4 92.3 20.5 51 60 61.5 71.9 61. 0 1.5 69 69.1 79.5 69.5 1.3 2 3 4 STAT1 1 9.5 303.0 49.5 30 30 30 30 29.3 -0.5 19.5 79.5 20 9.5 60 60 60 59.5 60 50 40 30 19.5 60 60 69.5 90 99.5 69.5 100 99.5 99.5 99.5 80 79.5 89.5 0.5 253 276.5 89.3 0.2 40.2 0.7 0.5 20 19.3 59.5 0.2 29.5 99.5 301.5 99.5 124.5 29.5 79.5 302 1 Station distance measured with a 300-foot fiberglass tape.5 201 225.5 226 251 251 276.5 89.5 99. observer #1 5 9.5 99.5 99.5 174.3 -0.0 -0.5 174.5 79.5 150 174 69.5 251 276.5 279 251.4 149.5 124.5 124.5 29.5 30 40 49.5 89.5 79.5 149.2 69.3 174.5 124.0 0.5 149.5 40 40 40 40 40 40 40 50 59. .5 124.2 19.5 89.5 125 149.5 -0.5 174.5 175 200.5 175 200.7 0.9 0.5 254 277 301.5 276.7 0.5 9.4 251.0 277.5 19.5 124.5 50 49. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 3.5 20.5 200.5 226 251 278 303 301 302 277 276.5 149.0 -0.5 90 89.1 99.5 251 225.7 0.5 200.5 99.5 0.5 99.3 200.6 2.5 79.5 79.5 9.5 278.2 1.5 251.5 -0.5 69.5 79.280 feet (1 kilometer).5 201.5 50 50 49.5 10 9.5 124.5 201 174.5 79.5 9. Manufacturer's claim of meter accuracy at distances = ± 3 foot (1 meter) to low quality targets.5 49.5 69.5 0.5 69.5 301 303.5 89.5 9.8 1.5 -0.1 -0.5 9.5 -0.5 9.5 9.5 226.5 -0.5 226.0 0.5 20 20 20 30 30 30 40 40 40 50 49.5 89.5 150 175 201 226 251 301 200.5 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.5 79.6 1.5 40 49.5 280 300 303.5 19.3 -0.5 20 19.5 225.5 2.5 125 124.0 89.8 0.5 302. 3 Change = Average distance recorded with rangefinder minus measured distance.5 89.5 60 60 60 70 69.0 124.5 49.5 29.Evaluation of Laser Rangefinders 36 Table 18—TruPulse 200B.5 60 69.5 60 69.8 0.0 -0.3 302.5 149.3 226.8 0.5 9.5 150 99.5 126 150 150 150 175 175 175 200 201 201 225 226 226 250 251 252 275 279.5 174.5 9.5 149.5 89.5 226 201 175 150 124.5 226.5 125.5 89.5 79.5 79. 4 -0.5 40 49.5 69.5 79.5 303 1 Station distance measured with a 300-foot fiberglass tape.4 2 3 4 STAT1 1 10 20 29.5 276.5 59.5 59. Manufacturer's claim of meter accuracy at distances = ± 3 foot (1 meter) to low quality targets.0 0.5 279.5 0.6 226.5 -0.5 0.5 226 124. Results 37 .5 10 20 19.5 29.5 100 125 126 125 150 149.5 200 227 251.5 -0.5 0.9 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.5 80 79.6 1.5 99.5 79.5 279 304 19.5 175.5 252.5 89.6 0.5 276.5 225.2 59.5 49.4 -0.0 49.6 0.5 149.6 200.0 89.7 0.5 149.5 69.5 125 174 173 201.5 225.5 79.0 0. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 3.2 19.5 19.5 79.5 1.5 19.5 125.5 49.5 200.5 40 40 40 50 49.9 -0.5 252 278.5 125 99.5 79.6 0.5 89 99.5 149.5 79.5 277 300 302.5 226 250 251 251 251.5 79.5 59.3 124.5 276 275 280.2 69.5 29.5 69.5 89.5 19.5 29.5 89.5 302 40 40 40 40 40 40 30 29.5 303 225.5 174 149.5 19.5 50 49.5 99.5 60 69.5 89.5 49.7 277.5 20 10 10 10 9.5 79.5 79.5 69.7 2.5 29. observer #2 5 9.5 174.5 89 92 89.5 50 60 59.Table 19—TruPulse 200B.8 99.5 251.5 124.4 -0.1 -0.5 60 59.5 69.5 60 59.5 20.4 302.5 29.0 79.5 69.2 174.5 149.5 29.5 0.5 301.5 150 174 200 225.5 124.5 124.5 99.5 149.5 40 49.5 150 175 174.5 79.2 0.7 251.5 40 49.5 174 200 201.6 2.5 251.5 99.5 89.3 -0.5 69.5 49.7 0.5 99 99 124.5 29.4 0.5 100 99.5 125 149.5 201 174.5 149.5 19.5 277 302.5 19.9 0.5 79.5 301 302.280 feet (1 kilometer).5 277.5 70 69.5 60 69.5 69. 3 Change = Average distance recorded with rangefinder minus measured distance.5 90 89 89.7 0.5 225.5 201 225 226.1 -0.5 303.5 251.3 -0.5 99.0 -0.3 29.0 1.5 100 125 150 174 200 227 252 59.2 40.5 277.5 49.5 227 200 200.5 40 30 20 10 10 9.4 0.5 59.5 302.6 0.5 251 276.5 174 200 225.5 30 29.5 253.5 174 200.5 10 10 10 9.5 69.5 -0.5 149.8 0.5 301 89. 5 49.5 19.8 1.5 149.5 250.5 301 40 40 40 40 40 40 30 30 30 30 30 30 30 40 49.5 124.5 124.5 59.5 99 124.5 19.3 124.5 19.5 200.5 150 175 174.5 124.5 -0.5 201 226.0 -0.5 276.5 125 150 149.1 40.5 149 175 202 225.2 0.5 0.5 174.5 251 276 300.5 149.0 -0.5 9.5 149.5 201 227 251.5 60 59.5 226 250 251 251 275 277 278 300 301 303 1 Station distance measured with a 300-foot fiberglass tape.5 174.5 89.5 99.8 -0.5 303 276 303.5 227 250.5 49.5 59.5 59.5 301.3 201.5 276 202 201 175 175 149.5 89.5 59.1 99.5 251 276.5 9.5 149.5 59. .5 30 40 49.5 49.5 69 79 89.5 49.5 175 201.5 9.5 19.5 0. observer #3 5 9.5 0.5 175 201 226.6 276.5 60 49.5 99 99 99.5 79 89.0 -0.5 124.5 276 301 19.5 175 200 201 201 225 225.2 1.6 0.5 20 19.5 149.5 200.0 0.5 99 125 175 202 69.0 30.5 19.5 149.5 79 79 79 79.5 69.6 301.0 0.5 124.5 1.5 149.0 49.5 276 302.5 79 89. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 3.5 69.5 79 89.5 251 277 277 301.5 59.5 0.5 79 69.5 59.5 100 100 99.5 99 89.2 1.8 0.5 49.5 19.5 252.5 19.5 69.5 9.4 -0.8 2 3 4 STAT1 1 9.5 0.1 89.2 0.1 174.5 0. Manufacturer's claim of meter accuracy at distances = ± 3 foot (1 meter) to low quality targets.5 226 124.5 69.5 250.5 -0.2 1.5 30 30 30 40 40 40 50 49.5 -0.0 0.5 19.5 69.5 40 29.0 59.1 69.280 feet (1 kilometer).5 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.8 251.5 301 225 226.0 0.5 59.5 69.5 9.5 9.1 79.5 0.2 0.5 250.5 226 250.5 226.5 -0.5 70 69.5 30 40 49.5 9.5 9.0 0.5 19.5 99 99 125.5 -1.5 301.5 79 89.5 9.5 99 124.5 0.5 69.5 125 124.5 49.5 -0.5 69.5 10 9. 3 Change = Average distance recorded with rangefinder minus measured distance.0 19.5 9.5 49.5 276.5 59.Evaluation of Laser Rangefinders 38 Table 20—TruPulse 200B.5 59.5 227.5 149.5 89 89.5 89.5 174.5 19.3 149.5 80 79 79 90 89.5 175.0 1. 6 0.6 10 9.2 -0.9 59.2 124.1 69.9 0.5 99.3 275.6 275.3 2.1 275.9 9.2 225 175 175.5 301 250 226.8 0.9 29.7 124.9 124.2 275.6 225.9 124.3 224.1 150.Table 21—LaserAce 2D and 3D.6 50 49.7 19.7 9.7 49.2 200 201.2 301.4 208.4 89.5 203.9 29. Results 39 .2 20 19.2 -0.1 275.2 275.8 225.4 100.5 301.7 29.0 0.2 301 89.4 175 150.6 3.2 250 250 250 275 274.6 225 250.8 275.4 39.6 9.1 0.7 49.9 80 80 89.9 79.8 30.6 99.3 49.1 276.6 1.3 -0.7 19.6 39.9 59. Manufacturer's claim of meter accuracy at distances = ± 0.3 0.2 175.7 9.5 0.6 80.8 69.9 30 30.8 70 69.7 29.6 49.5 200.4 99.4 89.1 20.6 39.6 9.6 275.7 0.1 39.1 200.0 -0.1 20.1 100.5 99.9 99.5 69.6 60 59.6 29.7 149.6 29.2 0.1 225 257.9 124.7 210.1 20.6 89.4 0.6 0.7 206.5 19.4 200.9 180.4 250.6 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.2 301 301.9 175.6 69.2 150 124.4 200.5 250.7 9.2 2 3 4 STAT1 1 9.1 89.4 250.7 124.1 154.6 80 80 79.8 99.6 39.1 40 39.9 69.0 0.6 29.8 49.6 29.6 124.8 0.1 -0.6 39.5 79.5 225.6 39.5 59.7 275.2 225.6 29.8 201.1 200.8 60.7 59. observer #1 5 9.8 39.6 69.8 49.6 300 301 301 1 Station distance measured with a 300-foot fiberglass tape.6 80 89.7 39.1 0.6 99.1 89.1 250.7 49.6 9.1 -0.5 80 79.1 49.9 69.7 150 149.2 301.6 250.1 175.4 0.1 0.5 0.7 150 150 150.5 0.7 125 124.4 175 175 175.5 100 99.2 124.2 275.7 99.5 49.6 39.6 80 89.6 69.1 3.7 224.8 60 60 59.2 59.6 50.4 301 20.4 1.9 150 175.6 39.1 20.7 150.1 204.4 175.1 69.7 19.0 29.5 39.8 49.6 29.1 256.7 69.1 124.8 89. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 500 feet (150 meters) 3 Change = Average distance recorded with rangefinder minus measured distance.8 225 250.1 89.2 -0.9 150.4 -0.7 60 69.7 124.6 124.7 49.4 301 225 224.2 foot (5 centimeters).4 275.0 80.1 1.7 59.5 9.5 80.5 89.6 59.7 301.4 251.1 200.1 99.1 20 20 20 9.4 100.4 301.8 0.7 150 175.9 90 89.5 -0.7 9.8 225.5 1.1 175.6 69. 3 150.1 100.6 9.5 9.7 79.1 300.3 40 30.3 300 300.2 70 80 90.7 0.7 2.9 175.2 0.2 100.7 250.1 8.2 0.1 70.5 19.5 126.Evaluation of Laser Rangefinders 40 Table 22—LaserAce 2D and 3D.1 275.0 79.6 199.4 60.5 275.4 0.2 100.1 90 90.9 275.1 0.3 0.3 225.9 9.3 249.8 70 60.3 60.2 0.4 255.3 300.9 50 50. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 500 feet (150 meters) 3 Change = Average distance recorded with rangefinder minus measured distance.9 150 149.3 125.1 203.9 39.2 0.6 250.3 300.4 225.2 foot (5 centimeters).1 70.2 0.5 225.2 60.1 100.6 90 70 70.1 175.1 79.6 9.3 60.2 250.5 9.1 177.5 30.3 150.1 70 79.5 300.5 5.3 50.5 0.9 250 250.3 275.1 40.6 276.4 125.1 50.1 175.1 276.9 40 50.7 19.5 3.7 90 100.1 200.1 0.3 125.2 0.2 50.3 150 149.1 70 70 70 60.3 150.8 250.1 250 275. observer #2 5 9.6 225.3 60.2 30.8 249.3 175.5 30.3 300.2 30.2 300.7 199.5 249.2 19.1 79.3 125.5 200.3 250.4 0.1 40 39.1 89.1 100.7 225.3 100.8 199.2 60.6 225.0 -0.0 0.1 0.6 30.9 90 90 90.9 202.2 199.3 200 213.6 1.5 200.6 19.6 250.9 80.3 213.7 225. .1 0.4 -0.1 60.1 175.2 50.5 300.1 0.5 9.6 100.2 60.3 0.5 0.1 80 79.1 30 19.5 150 149.1 125.3 300.1 0.7 9.3 225. Manufacturer's claim of meter accuracy at distances = ± 0.7 9.1 275.9 39.1 175 175.2 125.5 225.2 1 Station distance measured with a 300-foot fiberglass tape.2 40 50.1 100.2 249.3 300.1 300.2 90.2 100.9 80 79.2 40 50.9 150.5 20 19.6 19.3 100.1 30.6 177.2 100 100.5 30 30.2 79.3 50.6 0.8 275 275 275.8 225.5 0.4 19.2 125.6 9.9 250.4 125.2 60.1 125.9 175.8 79.2 70 80 90.6 275 150 149.4 90.2 70 70 70.8 90.4 176.6 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.8 199.2 0.2 50.2 125.0 0.2 50.2 50.2 275.1 125 125.6 19.3 300.5 19.1 0.1 30.3 228.3 156.8 225 225.5 19.9 150 175.3 39.9 40 40 40 39.9 0.3 60.2 275.3 60 60.1 199.2 90.3 19.5 175.1 -0.1 2 3 4 STAT1 1 9.4 50.5 19.4 125.3 300.1 100.1 30.5 10 9.0 0.5 175.2 30.6 9.1 30. 8 249.2 249.9 300 300 300.9 175 174.1 60.3 274.7 89.6 79.9 30 29.8 89.2 274 300.3 -0.8 0.8 19.2 125 125.2 69.3 274.8 149.8 39.1 125.5 224.8 20 19.9 9.9 0.3 174.3 174.8 19.6 249.9 29.0 -0.2 224.9 40 40.5 89.2 0. Manufacturer's claim of meter accuracy at distances = ± 0.3 274.9 9.5 224.2 69.1 50.1 50.5 199.1 125.1 274.8 29.2 249.9 19.1 149.8 150 174.1 50.2 60.2 224.9 39.9 9.1 60.6 79.6 224.7 1.8 19.6 224.4 -0.7 225 225.1 125.9 50.5 174.1 60.7 99.3 199.9 10 9.1 60. observer #3 5 9.4 199.1 0.2 150 150.Table 23—LaserAce 2D and 3D.3 0.2 89.1 29.9 29.1 0.1 0.8 19.2 249.1 299.3 99.2 99.2 300 300.8 29.9 39.9 9.5 224.6 0.7 -0.3 99.1 199.2 69.8 79.6 224.1 125.8 300 125.1 1 Station distance measured with a 300-foot fiberglass tape.4 200 199.1 79.9 39.8 0.8 79.2 50.2 249 149. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 500 feet (150 meters) 3 Change = Average distance recorded with rangefinder minus measured distance.3 174.1 0.2 39.6 199.3 274.8 0.5 249.4 275 274.1 150 174.4 100 99.8 19.9 29.9 29.9 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.1 39.3 300.5 174.8 79.1 50 50.1 89.1 0.8 69.1 50.0 0.2 50.2 60.7 60.1 19.3 -0.1 149.7 79.8 39.1 0.9 19.3 300.6 0.6 99.2 0.2 39.2 99.1 125 99.5 274.2 -0.8 29.2 -0.7 19.2 39.2 -0.7 174.8 69.2 300 249.9 79.3 199.2 89.7 79.2 300.9 40 39.8 0.1 70 69.7 200.7 224.9 50.9 50 50.4 19.8 199.2 60 60.4 199.7 89.1 149.7 199.7 89.8 9.7 69.6 250 249.8 0.3 99.4 249.7 0.7 19.9 50 60.1 69.8 29.3 69.6 79.8 60.8 9.9 9.7 89.8 224.5 224.1 60.9 273.2 -0. Results 41 .2 foot (5 centimeters).8 9.3 79.2 249.1 125.8 9.9 69.5 249.1 274.1 -0.2 299.7 69.2 50.8 39.7 69.8 99.1 60.6 89.8 29.8 99.2 0.7 90 89.7 89.4 -0.7 0.7 199.8 178.1 125.2 125.1 151 174.1 2 3 4 STAT1 1 9.2 274.2 149.4 174.1 69.2 125.8 9.2 99.8 149.8 29.3 -0.2 274.4 174.3 199.8 89.1 150.5 224.1 125.9 29.7 79.8 19.2 -0.8 150.7 80 79.1 125.1 60.9 300 274 249.2 99. 0 89.9 39.3 20.Evaluation of Laser Rangefinders 42 Table 24—Leica Disto D8.0 59.2 20.0 9.9 79.4 20.0 20.0 10.2 40.2 -0.0 0.8 49.3 60.4 80.0 49.0 20.7 --- 10.0 59.0 40.9 70.5 70.4 30.3 0.1 -0.04 inch (1 millimeter) up to 33 feet (10 meters).2 30.8 49.9 89.1 2 3 4 STAT1 1 10.0 20.8 61.7 89.4 125 Did not try 1 Station distance measured with a 300-foot fiberglass tape.6 89.3 30.9 40.7 102.1 0.9 89.1 10.0 0.8 60.0 79.9 60.3 30 30.5 90 90.0 49.5 89.7 0.2 20.8 0.1 99.8 60 59.0 6 7 8 9 10 11 12 10.8 99.0 -0.9 49.0 0.1 39.5 30.6 69.9 59.0 79.8 60.4 99.0 20 20.9 89.0 70.2 30.8 49.2 39.2 40 39.0 0.3 30.1 0.0 39.9 89.0 79.0 71.2 0.0 20.8 59.0 0.8 99.8 69.0 70.8 39.0 10.4 99.8 49.1 39.9 79.5 49.9 89.9 50 49.9 69.3 0.3 30.9 79.1 49.9 49.9 30.3 -0. .8 60.0 10 10.3 20.7 89.6 99.0 81.3 20.8 89.8 80.0 60.6 99.1 30. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 328 feet (100 meters) 3 Change = Average distance recorded with rangefinder minus measured distance.0 70 69.6 100 99. observer #1 5 10.1 40.9 79.0 49.8 60.2 30.9 10.9 89.2 0.7 99.8 99.1 30.8 39.8 79.8 --- READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 10.0 10.9 1.4 10.0 49.9 0.3 20.9 80 79.3 20.3 30.8 40.0 0.0 70.7 80.5 69.9 69.9 69. Manufacturer's claim of meter accuracy at distances = ± 0. 3 60.4 30.5 30.2 80.3 50.0 100 99.4 60.5 70.9 --- 50.3 30.2 80.9 --- 80.9 --- READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 10.4 40.2 2 3 4 STAT1 1 9.9 99.1 80.0 60.4 30.4 50.3 70.3 0.9 20.04 inch (1 millimeter) up to 33 feet (10 meters).4 0.1 0.Table 25—Leica Disto D8.9 10.1 90.2 89.0 20 20.3 0.1 0.1 80.2 80.1 50.2 89.0 20.3 9.4 0.0 90 90.2 60 60.1 0.0 90.5 30.0 0.0 10.3 10.0 10 9.3 30.1 89.3 40.3 50.8 80.3 60.0 10.9 89.8 0.1 91.3 40.3 70.4 20.3 40.1 70.3 50 50.7 1 Station distance measured with a 300-foot fiberglass tape.3 0.4 50.2 50.9 --- 6 7 8 9 10 11 12 10.3 0.3 0.3 50.3 30 30.9 10.5 40.3 20.4 40.5 99.0 20.4 40.2 70.2 80.3 80 80.0 0.3 60.1 89.3 50.3 40.3 50.3 60.2 0.3 20. Results 43 .4 50.3 20.0 20.3 0.3 60.2 70.4 50.5 60.3 40 40.0 80.0 10.3 70 70.3 30.1 70.3 20.1 0.3 70.3 70.3 70.3 30.1 40.3 70.2 60.2 0.2 70. observer #2 5 10.1 90.4 30.3 60.5 40.1 -0.8 99. Manufacturer's claim of meter accuracy at distances = ± 0.1 89.5 20.3 40.4 0.0 30.2 80. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 328 feet (100 meters) 3 Change = Average distance recorded with rangefinder minus measured distance.8 --- 89.0 10.2 80.0 20.1 80.3 30.3 20.0 --- --- --- 89.3 60.4 40.9 --- 30.2 60.4 0. 8 59.8 49.4 --- 6 7 8 9 10 11 12 9.4 49.2 80.9 49.6 0.4 -0.8 0.3 40.8 59.5 --- READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 9.8 69.4 89.1 89.7 80.0 40.8 70 70.6 19.4 125.4 9.6 99.0 49.7 9. Manufacturer's claim of meter accuracy at distances = ± 0.0 40.3 19.9 50 49.2 89.4 39.8 59.9 59.8 40.0 99.6 10 9.2 89.6 89.9 49.4 40.3 0. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 328 feet (100 meters) 3 Change = Average distance recorded with rangefinder minus measured distance.8 0.7 99.7 9.3 125.2 0.4 30.9 70.4 30.4 89.1 49.9 70.3 89.4 -0.9 69.1 70.9 80.3 0.4 --- 49.4 30.0 80 80.6 80.4 125 125.0 70. .2 125.0 30.4 19.3 19.6 99.3 30.7 19.3 125.7 100 99.8 39.1 80.8 59.0 80.5 --- 99.4 0.8 59.4 19.4 --- 69.9 80.8 40.2 -0.04 inch (1 millimeter) up to 33 feet (10 meters).4 99.0 59.9 49.4 9.6 99.8 49.6 0.2 70.6 99.3 40 39.4 19.9 49.8 49.Evaluation of Laser Rangefinders 44 Table 26—Leica Disto D8.9 39.4 30 30.1 40.6 89.3 30.4 30.0 40.6 0.2 -0.8 70.6 9.6 19.0 80.0 69.6 0.8 69.8 70.2 89.3 30.4 30.3 30.2 -0.4 19.3 40.8 60 59.9 59.9 59.3 1 Station distance measured with a 300-foot fiberglass tape.6 9.7 99.1 -0. observer #3 5 9.3 --- 30.1 89.4 99.0 0.0 0.8 59.0 125.4 19.1 19.6 9.2 80.9 30.2 89.0 80.9 80.3 99.7 9.9 49.8 59.3 2 3 4 STAT1 1 9.0 59.6 99.2 0.0 80.3 125.2 0.2 90 89.4 0.7 19.3 0.3 89.5 20 19. 2 1.0 1.0 91.8 152.9 0.5 227.5 30.2 0.2 1.7 41.6 0.7 0.6 202. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 4 to 1.4 2.8 3.9 1.000 yards. observer #1 5 22 31 41 52 61 73 82 91 101 127 153 177 202 227 253 280 303 303 253 279 303 203 227 254 281 303 71 82 91 102 127 153 177 202 228 256 280 303 62 52 51 62 71 82 91 101 129 152 177 203 232 253 279 303 41 41 31 30 30 41 52 62 71 82 91 102 128 153 177 202 229 257 278 303 22 22 22 22 30 41 52 62 71 82 91 101 127 152 177 202 227 252 278 303 253 279 229 203 202 227 176 177 152 153 152 177 127 127 127 101 101 101 92 91 91 82 82 82 72 72 71 62 62 62 52 52 52 41 41 41 30 31 31 22 22 21 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 21.7 1.0 2 3 4 STAT1 1 21 31 41 52 62 72 82 92 102 127 151 176 202 227 252 278 301 303 280 253 227 203 178 152 127 101 91 82 71 62 52 41 31 22 10 too close 20 21 21 30 32 30 40 42 42 50 52 52 60 62 62 70 72 72 80 82 82 90 91 91 100 102 102 125 127 129 150 154 151 175 178 177 200 203 202 225 227 227 250 254 256 275 278 278 300 304 304 1 Station distance measured with a 300-foot fiberglass tape.4 101.4 0.8 1.4 51.7 0.4 2.4 0.8 1.9 177.7 0. 45 .0 3.6 279.0 1.5 253.2 0.3 0.3 2.6 2.9 1.7 82.0 0.9 0.Table 27—Opti-Logic 1000LH.0 0.0 303.4 2.7 1.4 0.8 4. 3 Change = Average distance recorded with rangefinder minus measured distance.5 127.0 0.3 61. Manufacturer's claim of meter accuracy at distances = ± 3 foot (± 6 foot for very Results bright or dark targets).0 2.3 71. 4 0.5 3.5 253.8 0.1 0.5 1.8 0.6 303.1 204.1 0.4 2.0 4.7 0.3 61.0 3. 3 Change = Average distance recorded with rangefinder minus measured distance.1 0.000 yards.2 177.5 0.7 1.9 127.5 51.0 0.5 71.7 4.Evaluation of Laser Rangefinders 46 Table 28—Opti-Logic 1000LH.6 2.7 82.1 3. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 4 to 1.5 1. observer #2 5 20 31 40 51 62 72 82 91 101 128 153 177 202 228 252 284 302 279 302 228 252 279 305 82 91 102 127 156 179 202 228 252 279 302 72 62 62 71 82 92 101 127 154 180 203 228 254 278 306 51 51 40 41 41 51 61 71 82 91 101 127 152 179 210 228 255 279 303 31 31 31 21 21 21 20.9 228.7 2.5 2.1 1.0 2.6 0.4 2 3 4 STAT1 1 20 30 41 51 62 72 82 91 102 127 152 177 207 228 252 278 307 306 281 252 227 208 177 152 127 101 91 82 71 62 52 40 31 21 10 too close 20 20 21 30 30 31 40 40 41 50 51 51 60 62 62 70 72 72 80 82 82 90 91 92 100 102 104 125 127 127 150 153 154 175 177 178 200 204 205 225 228 228 250 252 253 275 279 279 300 302 304 1 Station distance measured with a 300-foot fiberglass tape.6 0.0 91.0 1.5 1. Manufacturer's claim of meter accuracy at distances = ± 3 foot (± 6 foot for very bright or dark targets). .4 279.8 0.0 1.6 0.4 1.2 20 31 40 51 62 71 82 94 101 127 155 177 202 229 256 280 300 279 302 254 229 228 252 202 202 177 177 177 201 154 154 153 127 127 127 102 102 101 91 91 91 82 82 82 71 73 71 61 62 61 51 51 51 41 41 40 30 31 31 21 21 20 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 0.5 40.8 1.1 3.3 153.5 30.9 101. 2 Range of meter's ability to take accurate measurements (per manufacturer) = 4 to 1.2 0.7 4.2 1.3 0. observer #3 5 21 31 41 52 63 72 82 91 102 127 153 175 205 227 254 281 303 282 303 203 228 255 277 307 82 91 102 128 153 176 207 228 255 278 303 72 63 63 72 82 91 103 129 153 176 204 228 255 278 308 52 52 41 41 41 52 62 72 82 91 102 127 153 176 204 229 253 278 303 32 31 31 21 21 21 21.Table 29—Opti-Logic 1000LH.000 yards.2 0.9 4.2 5.5 72.0 0.0 0.4 41.3 2.0 31.0 0.0 0.7 0.0 2.2 1.0 1. 3 Change = Average distance recorded with rangefinder minus measured distance.4 4.0 1.3 2.0 175.7 227.0 2.5 254.8 2.2 0. Results 47 .4 0.2 2.0 0.5 127.0 0.0 91. Manufacturer's claim of meter accuracy at distances = ± 3 foot (± 6 foot for very bright or dark targets).5 204.9 0.7 2.5 21 31 41 52 63 73 82 92 102 128 153 176 203 228 253 279 308 278 308 253 228 228 253 203 207 176 176 176 153 153 153 128 127 127 102 102 102 91 91 91 82 82 82 72 72 72 63 62 62 52 52 52 41 41 41 31 31 31 21 21 21 6 7 8 9 10 11 12 READINGS2 (all measurements are in feet) STAND AVG DEV CNG3 1.4 82.4 1.8 1.0 62.6 305.3 2 3 4 STAT1 1 21 31 41 52 63 72 82 91 102 127 153 175 208 228 255 281 303 309 281 253 228 204 175 153 127 102 91 82 72 63 52 41 31 21 10 too close 20 21 21 30 31 32 40 41 41 50 52 52 60 63 62 70 73 72 80 82 82 90 92 91 100 103 103 125 127 127 150 153 153 175 176 175 200 205 204 225 228 227 250 257 257 275 278 279 300 305 303 1 Station distance measured with a 300-foot fiberglass tape.2 2.4 3.0 52.5 279.4 102.7 0.7 153. 48 . Three observers took 12 measurements 80 feet from the target. and LaserAce to take accurate HD measurements to a target that was partially (about 80 percent) obscured by understory vegetation. (The TruPulse was the first device tested in dense brush. except for the tests using the farthest-line feature of the TruPulse. TruPulse 360 (w/reflector) See table 31 for the results of HD measurements using the TruPulse 360 with a reflector. We subsequently changed the evaluation to involve 3 observers who took 12 measurements 80 feet from the target. It bears repeating. We used 2 observers taking 12 measurements at 60 feet from the target.) Vertex Laser (ultrasound) See table 30 for the results of HD measurements using the Vertex Laser VL400 (ultrasound). however. we examined the ability of the Vertex Laser VL400 (ultrasound mode). The results are very precise and within the manufacturer’s claims of accuracy.Evaluation of Laser Rangefinders Rangefinder Horizontal Distance (HD) measurements through dense brush As previously mentioned (see Test Course section). TruPulse 360. We report reasonably accurate and precise results. that ultrasound measurements are limited to within 100 feet of the target. 1 80.6 0.6 80.1 -0.7 0.6 80.7 78.5 80.1 80.5 80.8 0.1 80.5 80.9 0.) 2 Change = Average distance recorded with rangefinder minus measured distance.9 80.) 2 Change = Average distance recorded with rangefinder minus measured distance. Manufacturer's claim of meter accuracy at distances is 1 percent or better.5 80.7 80.0 -0.9 79.6 80.Table 30—Results of HD measurements using the Vertex Laser VL400 (ultrasound) 5 80.5 80.5 79 READINGS1 (taken 80 feet from target) 8 79 80.5 80 80 STAND AVG DEV CNG2 79.5 80.7 0.4 #1 80.5 80.8 80. (All readings are in feet.7 80.5 6 7 8 9 10 11 12 READINGS1 (taken 80 feet from target) STAND AVG DEV CNG2 80. Results 49 .5 80.7 -1.8 80.9 80.2 0.6 #2 80.0 0.6 80.7 0.4 80.2 80.8 81.6 80.7 80.2 80.8 0. (All readings are in feet.5 80. Table 31—Results of HD measurements using the TruPulse 360 with reflector 5 79 80 80 79 78 79 6 7 79 79.5 78 9 79 78 79 10 79 80 79 11 79 80 79 12 79.4 -1.7 80.7 80.8 #3 81.8 Observ 1 2 3 4 79 79 80 79 79.2 81.2 0.1 ALL ALL 3 OBSERVERS COMBINED 1 Distance measured with a fiberglass tape.6 80.5 79 #1 79 79 #2 80 80 #3 77 79 ALL ALL 3 OBSERVERS COMBINED 1 Distance measured with a fiberglass tape.1 79.7 Observ 1 2 3 4 80.9 80. Manufacturer's claim of meter accuracy at distances = ± 1 foot to high-quality targets.5 0.6 81.5 0. we report less precise results as some HD reading might have been of the farthest understory shrub and not the intended target. LaserAce (using last-hit feature) See table 33 for the results of HD measurements using the LaserAce last-hit feature. the LaserAce was very accurate taking HD measurements to an unobstructed target. the LaserAce and TruPulse both have features (last hit/farthest line) that allow the user to disregard HD measurement readings to closer foliage and possibly capture the HD to the intended target in the background. CONCLUSION The results demonstrate that precise and accurate HD measurements through a dense understory are possible. even when taking measurements in the last-hit mode. (Note that the LaserAce was surprisingly accurate (if not precise) even when taking last-hit measurements. As shown in tables 21 through 23. Nevertheless. reasonable accuracy is possible in this measurement mode. 50 . if it is practical for the user to attach a transponder or reflector to the intended target site. This method produces less precise (or accurate) results relative to using a reflector or transponder. but it may meet the needs of many users.Evaluation of Laser Rangefinders TruPulse 360 (farthest-line mode) See table 32 for the results of HD measurements using the TruPulse 360’s farthest-line feature.) Rangefinder distance measurements between two objects and measurement of height of objects Since the primary objective of the evaluation was to test a rangefinders’ ability to take HD measurements. If occupying the target site is not desirable (or practical). investigating the ability of devices to measure between two objects and take height measurements was cursory. As might be expected. Conclusion 51 .4 -3.6 1.5 58 #2 58 56 ALL BOTH OBSERVERS COMBINED 1 Distance measured with a fiberglass tape.5 58 54 58 #1 57.) 2 Change = Average distance recorded with rangefinder minus measured distance.9 2.1 80 6 7 8 READINGS1 (taken 60 feet from target) 9 79.8 Observ 1 2 3 4 57.3 1.5 58.1 79.3 0.1 80.7 0.Table 32—Results of HD measurements using the TruPulse 360 farthest-line feature 5 56 52 58 58 58 58 57 58 58 58 56 58 57.6 0.7 0.5 11 80. Manufacturer's claim of meter accuracy at distances = ± 0.2 81.3 80.6 81 80.7 81.3 81.5 80.4 81 80.3 12 81.5 0.1 80.6 81.9 81 78. Manufacturer's claim of meter accuracy at distances = ± 3 feet (1 meter) to low- quality targets.2 78.9 81 81.6 0.4 80.8 ALL ALL 3 OBSERVERS COMBINED 1 Distance measured with a fiberglass tape.8 81. (All readings are in feet.4 80.4 #1 80 80 #2 80.8 56.5 58 58 6 7 8 9 10 11 12 READINGS1 (taken 60 feet from target) STAND AVG DEV CNG2 57.2 79.5 -2. (5 centimeters).5 Observ 1 2 3 4 81.0 57.9 80.1 #3 80.2 feet.9 0.4 81 10 78 81. Table 33—Results of HD measurements using the LaserAce last-hit feature 5 81.) 2 Change = Average distance recorded with rangefinder minus measured distance.6 79.3 81.7 81 STAND AVG DEV CNG2 80.1 -2.3 1. (All readings are in feet. 5 18.8 feet as measured with a fiberglass tape.8 17.8 18.6 7 17.9 18. We were surprised that the LaserAce was almost +2 feet off the true (measured) distance.5 17.5 6 18.6 5 18. Perhaps we may not have calibrated the device properly.7 #1 #2 #3 18. Change = Average distance recorded with rangefinder minus measured distance. Table 36 provides the results of our cursory test on the accuracy and precision of this ability.9 18.3 0.5 18. All devices provided reasonably accurate height measurements.8 3 19.6 18.4 1. even though we followed the directions from the user manual.8 1.5 0.6 18.7 AVG 18.6 18.5 18. and the results are shown in tables 34 and 35. given how accurate it performed in HD measurements.Evaluation of Laser Rangefinders Distance between two objects Both the LaserAce 3D and the TruPulse 360 have an intergraded compass that enables the user to take measurements between two stationary objects. The TruPulse gave readings that were reasonably precise (repeatable) and accurate.5 18.2 18.7 1. Table 34—LaserAce – using missing distance Observ 1 1 READINGS1 (ft) 2 18. We took several measurements with these rangefinders (at about 80 feet from the two objects) using this feature.4 18.2 18. 2 52 .8 4 18.7 18.7 1. Height of object measurements All rangefinders tested claimed to operate as a hypsometer (a device that can measure the height of objects).4 ALL ALL OBSERVERS COMBINED Actual distance between the two objects (trees) was 16.3 0.6 18. Rangefinder readings were taken at a point about 80 feet from targets.5 STAND DEV CNG2 0. 2 0.1 0.1 5. 2 Change = Average distance recorded with rangefinder minus measured distance.5 5.3 5.6 3 4 5 6 7 4.3 -0.7 5. Rangefinder readings were taken at a point about 80 feet from targets.5 5 Readings1 (ft) Avg 4.2 #1 16.2 16.3 16.5 5.5 16.4 -0.4 5.3 16.5 5.4 5.2 15.3 ALL BOTH OBSERVERS COMBINED 1 Actual distance between the two objects (trees) was 16.1 16.8 16.2 6 7 8 9 10 11 12 READINGS1 ft) STAND AVG DEV CNG2 0.6 Observ 1 2 3 4 16. Table 36—Results of cursory test on accuracy and precision of using rangefinder as hypsometer 2 4.2 16.7 Device 1 Vertex Laser 4.7 0.4 5.4 5.7 5.6 -0.3 0.9 16.3 16.5 Opti-Logic 5 1 Rangefinder readings were taken at a point about 20 feet from targets.5 -0.4 4.5 4.5 5.1 0.1 16.5 Disto D8 5.4 5.1 16. Conclusion 53 .0 Stand True Dev Height CNG2 0.4 5.4 5.6 5.7 5.4 5.2 LaserAce 5.5 0.using missing line 5 16.4 TruPulse 5.1 15.8 16 16 17.2 16. 2 Change = Average distance recorded with rangefinder minus measured (true) height.1 0.5 5.0 -0.3 16.7 16.2 -0.6 16.6 5 4.4 4.1 16 15.2 16.6 5.4 5.9 #2 16.4 5.5 5 5 5 5 5.4 5.Table 35—TruPulse 360 .3 5.3 -0.7 5.8 feet as measured with a fiberglass tape.0 4. We tested the following field rangefinders. Two new features that are now available are rangefinders with an integrated compass and a device that can operate by either laser or ultrasound. listed from most to least expensive: LaserAce 3D. and portable. A secondary objective was to test a device’s ability to take HD measurements to a target that was obscured partially by understory vegetation. In general. which operated by ultrasound only. the more accurate and precise devices were the more expensive. sturdy. the more expensive they are. Commercial rangefinders are now all lightweight. We found that rangefinder technology had improved significantly since the 1998 report. Vertex Laser VL400 (laser and ultrasound). such as an integrated compass or Bluetooth capability. and the Opti-Logic. except the Vertex IV. All devices operated by using a laser beam. Any user seriously interested in taking accurate and precise measurements should invest in a tripod. Vertex IV (ultrasound only). Intermediate accuracy (and expense) can be had with the TruPulse and Vertex Laser VL400. TruPulse 200B. LaserAce 2D. We found that ultrasound can be used to achieve very accurate HD measurements through a dense understory. If the user’s demand for accuracy is significantly less (say ±several feet). TruPulse 360. 54 . the LaserAce (the most expensive device tested) was accurate to within a few inches of what could be achieved from using a tape measure. Also. The Vertex Laser VL400 was a combination laser and ultrasonic device.Evaluation of Laser Rangefinders SUMMARY The primary objective of this evaluation was to compare and evaluate laser rangefinders’ accuracy and precision in taking horizontal distance (HD) measurements similar to an evaluation performed by SDTDC in 1998. an ultrasonic device has a range of only 100 feet. All devices tended to operate within the accuracy claims of the manufacturers. a relatively inexpensive option exists in the Opti-Logic. We tested the Lecia Disto D8. the more features a device has. If a user is interested in very high accuracy. but considered it more of a tool for a construction-site setting (as opposed to a field forestry tool). us/ For additional information on rangefinder technology. the user ignores readings that were taken when striking foliage in between the observer and the intended target. The device can be operated to show the readings of the farthest target it acquired (and hide the readings of the closer targets acquired) while laser beams were pulsed.fed.us/ eng/pubs/ USDA Forest Service and U. A rangefinder with an integrated compass expands the measuring capacity into three dimensions. Depending on the user’s needs and the features desired. The National Technology and Development Center’s national publications are available on the Internet at: http://www. In this mode. In that way.fs.S. and National Technology and Development Center’s individual project pages on their internal computer network at: http://fsweb. wo. the device only registers beams that are returned from a reflector attached to the target tree.fs. High-end devices can also operate with a foliage filter and reflector to obtain accurate HD measurements through a dense understory. contact Rey Farve at SDTDC. CDs. With a compass rangefinder. Bureau of Land Management employees also can view videos.fed. Department of the Interior. from one point the user can measure the distance between any two visible objects (two trees or edges of a streambank to determine stream width). Email: rfarve@ fs.Summary Laser rangefinders (high-end devices) have features that assist the user to obtain reasonably accurate field measurements even if there is a dense understory. a reasonably priced and reasonably accurate device should be available commercially.sdtdc.us 55 . These devices have features that help distinguish the understory from the intended target. Phone: 909–599–1267 ext 210.fed.