Estimate vegetation coverage percentage from a lidar dataset

Summary

Estimating vegetation coverage from a lidar dataset (LAS), in terms of percentage, can be done using the LAS Point Statistics As Raster tool. However, ground features are identified by classification codes in lidar datasets. Therefore, prior to estimating the percentage of vegetation coverage, the lidar points in the dataset must be classified.

For more information on working with classification codes in lidar datasets, refer to Working with LAS classification in ArcGIS.

Procedure

The following instructions describe how to use the LAS Point Statistics As Raster tool to quantify, extract, and estimate vegetation coverage in terms of percentage. For more information, refer to ArcGIS Help: LAS Point Statistics As Raster tool.

Once the lidar points are classified, the lidar point 'clouds' can be converted into a raster that shows the land cover, allowing the coverage to be quantified by using the LAS Point Statistics As Raster tool.

Note:
Ensure the lidar dataset ground features are identified and classified with the correct classification codes prior to using the LAS Point Statistics As Raster tool. 

1. Run the LAS Point Statistics as Raster tool and define the following parameters:
   • For Method, select PREDOMINANT_CLASS.

     This method assigns the most frequent class code to the pixel value in a pixel area. For example, in a pixel area covered by trees, lidar returns from layers of the canopy are more than returns from the ground. As a result, this pixel area has the land cover class of vegetation.

   • For Sampling Type, select CELLSIZE.
   • For Sampling Value, use the point spacing distance of the LAS dataset.

     The sampling value determines the pixel size of the output raster. With smaller pixel sizes, the accuracy and resolution of the estimation increases. However, if the pixel size is smaller than the point spacing distance in some pixel areas, no lidar returns are captured, resulting in NULL pixels.

2. Run the Build Raster Attribute Table tool on the output land cover raster to generate an attribute table for the raster. The attribute table contains the pixel counts for each land cover class.
3. Right-click the raster > Open Attribute Table > click Table Options > Add Field.
4. Name the field as Percentage_Coverage, and select Float as the Type.
5. Use the Field Calculator to populate the Percentage_Coverage field using the formula below:

   Percentage_Coverage = (Count/sum of Count) * 100

6. The vegetation coverage estimation can be found by cross-referencing the percentage values with the designated lidar points classification value for vegetation.