Difference between revisions of "QGIS Extract Ground Elevation"
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<li>Convert line vertexes to points, using the preferred method described in [[QGIS_Convert_Lines_to_Points | this page]]</li> | <li>Convert line vertexes to points, using the preferred method described in [[QGIS_Convert_Lines_to_Points | this page]]</li> | ||
<li>Open the Point Sampling Tool</li> | <li>Open the Point Sampling Tool</li> | ||
| − | [[File:QGIS Extract Ground Elevation 001.png| | + | [[File:QGIS Extract Ground Elevation 001.png|700px]] |
<li>Set the following:<br> | <li>Set the following:<br> | ||
* Select the point layer converted at step 2 as the "Layer containing sampling points" | * Select the point layer converted at step 2 as the "Layer containing sampling points" | ||
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* Set the output layer file name | * Set the output layer file name | ||
The plugin will create a new point layer file which contains all attributes in a 2d_zsh layer and the bed elevation as the 5th attribute. | The plugin will create a new point layer file which contains all attributes in a 2d_zsh layer and the bed elevation as the 5th attribute. | ||
| + | <li>Open the Attribute Table of the newly created layar. Toggle editing and update "Z" attribute with "dem_m01" as shown in the image below</li> | ||
| + | Now this point layer is ready to be input with the line layer. | ||
</ol> | </ol> | ||
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Revision as of 09:39, 20 February 2018
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
- Ensure that DEM and 2d_zsh line layer files are opened, and the Point Sampling Tool plugin has been loaded
- Convert line vertexes to points, using the preferred method described in this page
- Open the Point Sampling Tool
- Set the following:
- Select the point layer converted at step 2 as the "Layer containing sampling points"
- Select all the attribute in the point layer as well as the DEM as the "Layers to get value from"
- Set the output layer file name
- Open the Attribute Table of the newly created layar. Toggle editing and update "Z" attribute with "dem_m01" as shown in the image below Now this point layer is ready to be input with the line layer.
