Calculate Forest Metrics by Grid
Calculate the forest metrics based on the point cloud data in grids. Split the point cloud data with multiple grids, and then calculate the forest metrics in each grid. The forest metrics include elevation, intensity, canopy cover, LAI, and gap fraction.
First, this function will divide the point cloud into different grids with a certain size in the horizontal direction. And then Calculate the forest metrics based on users selection, and, for each grid, generate a CSV file or TIFF file to store the result.
Click AlS Forest > Forest Metrics > Calculate Forest Metrics by Grid to generate the selected forest metrics.
- Input: Make sure that all the input files are normalized. The input file(s) can be a single file or a file set. The file(s) to be processed must be opened in LiDAR360 before using this function.
- XSize (meter) (default value is "15"): The grid size in X direction. This value should be larger than the crown size of the trees. For the data acquired from most of the forest, this value should be larger than 15.
- YSize (meter) (default value is "15"): The grid size in Y direction. This value should be larger than the crown size of the trees. For the data acquired from most of the forest, this value should be larger than 15.
- Height Threshold (meter) (default value is "2"): The threshold to divide the data in vertical direction. The point cloud above this height will be used to calculate the forest metrics. The default value is 2.
- Leaf Angle Distribution (default value is "0.5"): A mathematical expression of leaf probability distribution in three-dimensional space, which is related to vegetation type, leaf angle, and beam direction. According to the empirical formula, the user can determine the value of leaf angle distribution according to the actual situation of the forest. Studies have shown that the elliptic distribution of leaf angle, which has a leaf angle distribution value of 0.5, may be applicable to the actual situation.
- Output Path: Path of the output file. A corresponding raster file (tif format) or CSV file will be generated for each input point cloud data, which can be used in the regression analysis.
- DefaultValue: Restore the default parameters.
Note: Only when the point cloud data is loaded in the software can you use the Elevation Metrics function; otherwise, the message "There is no point cloud data meeting the conditions of calculation!" will pop up. If the maximum Z value of the point cloud is greater than 200 m or the maximum Z minus the minimum Z is greater than 200 m, the data is not considered to have been normalized, and the prompt information shown in the figure below will pop up. Click “YES” to keep using this type of data in the operation; otherwise, click "NO" and reselect the input data file.