QGIS Creating a Grid from Points

Introduction

In this page a DEM is created from point shapefile containing elevations. For this example the zpt_check file from module 1 of the TUFLOW tutorial model will be used, but the process can apply to any point layer. This is useful for visualising the final elevations for a model simulation from a TUFLOW Zpt Check file.

Method

1. Open the desired shapefile in QGIS.
2. Select Plugins >>> Interpolation >>> Interpolation from the menu items.
3. In the Input section of the Interpolation dialogue, use the drop down list to select the appropriate Vector Layer, select the attribute to interpolate. This is the Elevation attribute if using a check file. Select Add to include this in the interpolation.
4. In the Output section of the dialogue:
   • Set a interpolation method. For this demonstration a TIN method is used, but feel free to experiment.
   • Set the X and Y cell size to an appropriate number (half the cell size if using a zpt_check file).
   • Specify the output file name.
   

   
   

5. Select OK and the interpolation will be processed, this may take a few minutes depending on the number of points.
6. In the properties dialogue, set the Style Colormap to "Pseudocolor" for a quick visualisation, or alternatively set a custom colormap. The grid should appear as below.

   Tip: To enable relief shading see the relief shading tip in the QGIS tips and tricks.