QGIS Extract Ground Elevation

Introduction

This page describes the method for extracting ground elevation (or any other variable) from raster files or polygon attribute using "Point Sampling Tool". This method is useful when you want to:

• Extract ground elevation for the points snapped to breaklines
• Define ground elevation for 1D nodes/pits snapped to 1D channel/pipes
• etc...

In the example below, the ground elevation for the 2d_zsh point layer in the TUFLOW Tutorial 03 is extracted from the DEM file.

Method

1. Ensure that the Point Sampling Tool plugin has been loaded, and DEM and 2d_zsh line layer files are opened
2. Convert line vertexes to points, using the preferred method described in this page
3. Open the Point Sampling Tool

4. Set the following:
   
   • The source layer to be the line file you wish to convert
   • The new geometry type to Nodes
   • The output file
   The plugin will create a new point file which contains all vertices along the line. If you wish to create intermediate points along the line you will need to use an alternate plugin. A plugin called Profile from Line appears to do this.