Application of large space 3D laser scanning system in forestry engineering

FARO Laser Scanner LS large space 3D laser scanning system is widely used in many fields such as mining, engineering, urban planning, construction, railways, etc. The working principle is that a laser generator device emits laser to a high-speed rotating mirror, and the laser is reflected by the mirror to emit to the objects in the surrounding environment. Through the reflection of the object, the laser receiver receives the reflected laser, and then calculates the angle of the distance sensor and encoder in the equipment to obtain the spatial 3D point cloud data of the object. When talking about its application in China, of course we have to talk about its successful application in the research of forestry survey and planning in Hebei Province.

Hebei Forestry Survey, Planning and Design Institute is the design unit with the highest qualification in forestry survey, planning and design in Hebei Province. Its main work is to be responsible for the dynamic monitoring of forest resources in the province, the preparation of feasibility studies in the early stage of forestry projects, and the later acceptance.

In the work, it is a common problem to obtain the volume of a tree in forestry survey. The mathematical method to solve this problem is: measure the diameter (DBH in forestry) of the tree (called sample tree in forestry) at three points of one meter, then cut down the tree, decompose the whole tree into sections of one meter, calculate the area of ​​each section, and finally add them up to get the volume of the whole tree. After taking a large number of samples, you can get a set of data corresponding to one volume for one DBH. Then perform regression analysis on DBH and volume, and finally get the relationship equation between DBH and volume. In the future measurement process, you only need to measure one DBH size to know how big the tree is, which is called accumulation in forestry.

The stocking problem is one of the most important tasks in forestry surveys. It is an important unit for describing forests. In 1978, Hebei Province used the method of felling standing trees to compile a set of stocking tables involving five tree species for production use. In forestry, it is called a one-yuan standing tree stocking table, which has been used to this day. However, in today's production, it is constantly found that the table has large errors and cannot meet current production needs, so the need to launch a new set of tables is imminent. Since felling trees for stocking requires a lot of financial and material resources, standing trees for stocking has always been a difficult problem to be solved in forestry!

The FARO Laser Scanner LS large-space 3D laser scanning system has brought many high efficiencies to their research and application. It can scan and acquire 8 million pixels of the surrounding environment in less than one minute, which is 100 times faster than the same type of 3D laser scanners, reducing the time required to capture data on site and improving work efficiency and profitability of data collection.

Hebei Provincial Forestry Survey, Planning and Design Institute has always been at the forefront of the same industry in the country in the innovation and application of new technologies. In November 2005, the hospital purchased a FARO Laser Scanner LS large-space 3D laser scanner, which was specifically used by Shi Junhai, director of the hospital's resource monitoring room. After a short period of training, the user quickly mastered the use of the machine and developed a dedicated analysis software by himself, successfully solving the scientific problem of standing tree volume.

First, after determining the measurement point in the field, the Laser Scanner LS was set up with a tripod and laser scanning was started to obtain accurate 3D point cloud data, so as to accurately calculate the diameter of each branch of the tree without cutting down the tree to obtain data.

Secondly, a scan can obtain data of multiple trees, so that the diameter of each branch of each tree can be accurately calculated, and it is no longer necessary to use a similar calculation method to count the volume of the entire tree, which greatly improves the accuracy of the data. Furthermore, personnel no longer need to stay in the field for a long time to measure, and it only takes less than 5 minutes to obtain data of trees within a range of 150 meters.

After nearly half a year of after-sales tracking, Shi Junhai, director of the hospital's resource monitoring room, summarized the features of using Laser Scanner LS:

1 Fast speed: In less than a month, more than 3,000 sample trees were collected in five cities and districts in Hebei, making the resulting equation more broad-spectrum and regionally representative.
2 High precision: The data obtained from actual measurements differs by less than two millimeters.
3 Stable operation: The machine has experienced the severe winter and spring sandstorms in the wilds of Hebei, and has run stably for nearly 2,000 times without any malfunction.
4 Reduced measurement workload: According to traditional methods, one tree requires four people to work for a day, but now two people can collect more than 3,000 sample trees in less than a month.

Director Shi Junhai commented on this method: After exchanges with peers in the same industry across the country, it was unanimously recognized by everyone as the most advanced tree measurement method to date. He said that in the future he would recommend FARO Laser Scanner to more colleagues in the industry to share the results brought by high technology. (end)