Figure 1.
Visualization of an illustrative CAT D6R dozer with a Velodyne VLP-16 LiDAR sensor and a measurement beam with the Hz angle of ±35°, V angle of ±15°, and measurement range of up to 6 m
Figure 2.
Velodyne VLP-16 LiDAR parameters: a) measurement beams (channels) in the vertical plane [42], b) dimensions of the measurement area [m]
Figure 3.
Prototype of the measurement system
Fig. 4.
Visualization of the prototype with the LiDAR sensor measurement angle used in the tests: Hz ±90°, V ±15°, and measurement range up to 6 m: a) top view, b) spatial view, c) side view
Figure 5.
Block diagram of the program based on the developed algorithm
Figure 6.
Visualization of the data matrix – a grid with a single pixel size of px. Each pixel, starting in the lower left corner, can only contain one point with data [X,Y,Z, Intensity, Hdiff]. The colors blue, green and yellow indicate the corresponding grid nodes (pixels) and measured points
Figure 7.
Point cloud (a), b)) and mesh model (c), d), e), f)) from the conducted test measurement: before (a), c), e)) and after (b), d) f)) the pile was modified with an excavator. The colours for graphics a), b), c) and d) are the LiDAR laser beam intensity, while for graphics e) and f) it is the height map. The area of changes has been marked with a red rectangle
Figure 8.
Screenshots from the program’s field application. The image a) shows a view of the cloud with LiDAR beam reflectance intensity colors, before the pile was modified. The image b) shows a view of the cloud where the colors of the points are determined by their height, after the pile was modified and the changes captured, just before the program stopped running
Figure 9.
Photos before (a) and after (b) the pile modification. Video from field tests is included in Appendix B
Table 1.
Maximum project dimensions depending on the selected resolution of DTM grid
| Grid resolution (pixel size) [m] | Max project area [m2] | Example dimensions [m] |
|---|---|---|
| 0.01 | 90,000 | 300 × 300 |
| 0.02 | 360,000 | 600 × 600 |
| 0.04 | 1,440,000 | 1200 × 1200 |
| 0.05 | 2,250,000 | 1500 × 1500 |
| 0.10 | 9,000,000 | 3000 × 3000 |
| 0.20 | 36,000,000 | 6000 × 3000 |
| 0.25 | 56,250,000 | 7500 × 3000 |
| 0.50 | 225,000,000 | 15000 × 3000 |
| 1 | 900,000,000 | 30000 × 3000 |
Figure 10.
Distances [cm] on the ground between points from all the 16 LiDAR channels, with the sensor mounted as specified: 3 m above the ground, at an angle of 45°, maximum distance 6 m
