Lidar Analysis of Vegetation Structure

This exercise was initially created as a session in a GIS training for the U. S. Fish and Wildlife Service in May, 2016 by Doug Newcomb.

Session Objectives

At the conclusion of this session, you will be able to:

• Open GRASS GIS and Create a Location from an existing file
• Link external raster elevation data to the Location
• Import LAS point cloud data to assess DEM accuracy
• Import LAS point cloud data to create various vegetation structure products
• Export raster vegetation structure data layers from GRASS to GeoTiff

Material Created By: Doug Newcomb (May 2016)

Software: GRASS 7.2

Directory Path: D:\grasslidar (assumed at some places, use any directory you want)

Image Files: D05_37_20026801_20141209.tif D05_37_20026803_20141209.tif D05_37_20026802_20141209.tif D05_37_20026804_20141209.tif

LAZ format LiDAR files: LA_37_20026801_20141209.laz LA_37_20026803_20141209.laz LA_37_20026802_20141209.laz LA_37_20026804_20141209.laz

Data can be accessed online here

Elevation data is commonly used in landscape analysis, but it is also quite useful in vegetation analysis. This exercise will walk you through basic analysis of a LiDAR point cloud to better understand vegetation structure.

All data are located in c:\grasslidar\data, unless otherwise noted.

Step 1: Creating GRASS Workspace The first thing to do when starting to work in GRASS is to create a Location. GRASS Locations are single projection areas with a defined resolution and extent. The initial location can be easily created from an existing data set.

In Windows, Click on Start-->All Programs-->GRASS GIS 7.2--> GRASS GIS 7.2 GUI

Two windows will open, the GRASS startup window ( to select or create a workspace) and the GRASS command prompt.

• Click on the New button between the Location and Mapset windows. This will bring up the menu to define a new Location.