China, a country with vast resources, is rich in forestry resources. How to plan the development of forestry, more accurate measurement of forestry resources, and more accurate inventory and cataloging of forestry resources focusing on timber sales have become important issues for the forestry department. Laser measurement technology will help promote the country’s forestry measurement into a new era.
The purpose of multifunctional laser measurement system
(1) Distance measurement—-Distance measurement is the main function of this instrument, which can directly display horizontal distance or tilt distance.
(2) Azimuth angle——It can directly display the magnetic azimuth angle or relative azimuth angle of the measurement target.
(3) Tilt angle——Can display tilt angle (vertical angle) or tilt percentage.
(4) Target coordinate program – The function of the target program is the so-called addressing or staking (setting out) function in measurement, that is, inputting its coordinates (X, Y, Z) at a known point into the instrument, and then the measurement can be done by aligning the measurement target. The coordinates of the measured position are immediately displayed.
(5) Height measurement – Use trigonometric principles (pitch, elevation angle and horizontal distance) to measure the height of objects, including tree height, building height, etc.
Discussion on the application of multifunctional laser measurement system in forestry
(1) Combination of multifunctional laser rangefinder and GPS
The introduction of multifunctional laser distance measuring meters was initially mainly combined with GPS. That is, GPS was used in conjunction with multifunctional laser meters for measurement in areas with restricted terrain.
Detailed application:
1) Censorship and inventory of illegally cultivated land
The use of laser distance measuring meters, combined with GPS, GIS and their software, and portable computers for environmental monitoring is currently the most popular research project in various academic institutions. In forestry, it is used for clearing and inventorying uncultivated land. However, since the use of GPS may be restricted by terrain, further research and testing are needed. In addition, it can also be combined with a digital camera to take photos of violations and archive them to provide evidence for banning.
2) Land rental inventory
The combination of multi-function laser distance measuring meters and GPS to conduct land lease inspection is not only fast but also highly accurate. In addition, the digital drawing files can also be pre-entered into a portable computer and brought to the site for inspection and comparison.
3) Inspection of security forests outside the area
At present, the bureau uses electronic flat-panel instruments to conduct inventory and stake placement work in security forests outside the area. However, due to insufficient triangulation points, inventory work is often slow. If centimeter-grade GPS can be used to lay out points, and then laser distance measuring meters can be used for measurement, and the target coordinate program function can be used for staking work, it should be possible to speed up the inventory work and reduce the subsequent work of digitizing maps.
(2) Forest land survey
Since the multifunctional laser measurement system combines laser ranging with an electromagnetic digital compass, its distance measurement and angle measurement accuracy are much higher than those of compasses and measuring ropes. It is indeed the best new instrument for forest land measurement.
According to the test, the advantages of using the multifunctional laser distance measuring meters for forest land measurement are:
1) Easy to operate, fast measurement locking and high accuracy. The instrument can automatically record data and transmit it to the computer without human clerical errors.
2) The digital instrument panel displays automatically and there is no human error in visual interpretation.
3) Save manpower and time.
4) Comes with processing software, which can process points, lines, and wires, calculate closing errors, areas, etc., and directly draw measurement graphics.
Data collection is used for forestry resource inventory, that is, tree height, height that can be used as commercial timber, vegetation mapping, locating wild special tree species and excellent tree species, determining the grade and economic value of trees in the area, or when conducting cultivation management research. Branches, determine tree locations where specific heights will occur, map harvest profiles, determine resource boundaries. For topographic surveying, mapping of bale passages when harvesting timber and considering bale methods, and for general purpose use. Pre-construction surveys of roads and rough trails are important. Using conventional surveys, aerial photography and GPS positioning that have been available in the past may encounter various problems (eg cost, accuracy, obstructions, etc.).
