此外在每个样区内围绕样地选取开阔无遮挡、地物明显位置均匀布设了6个地面

In addition to selecting the sample around an unobstructed open area in each sample, the apparent position of the feature six evenly laid ground control points (GCP) [27], to ensure a clear image can be used in RTK geographic coordinates measured on the photograph and elevation, horizontal and vertical accuracy control are ± 3 cm. Ground control and measurement point layout shown in Figure 2.

In addition, six ground control points (GCP) are evenly laid around the sample selection of open unobstructed and the apparent position of the ground, ensuring clear imaging on the image, using RTK to measure its geographical coordinates and elevation, and the horizontal and vertical accuracy of the control is .3 cm, respectively. Ground control points are laid and measured in figure 2.

In addition, six ground control points (GCP) [27] are evenly arranged around the sample plot in each sample area to ensure clear imaging on the image. RTK is used to measure its geographic coordinates and elevation, and the horizontal and vertical accuracy of control is ± 3cm respectively. See Figure 2 for layout and measurement of ground control points.<br>