Arc 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. This method requires the Spatial Analyst toolbox for ArcGIS.

Method

1. Open the desired shapefile in ArcMap.





2. Make sure the Spatial Analyst toolbar is visible.
3. In the Spatial Analyst Menu select Interpolate To Raster >>> Inverse Distance Weighting.
   

   Note: There are other methods for interpolating to a grid, feel free to experiment with these. The IDW method is generally quicker than Kriging, so this is used for the current demonstration.

4. In the dialogue:
   • Set the input points to the desired layer (I.e. Zpt check file);
   • Set the Z field to the Elevation field;
   • Use a fixed search radius no bigger than the cell size (to avoid a DEM that extents beyond the point layer);
   • Set the minimum number of points to 1;
   • Set the output cell size to half of the TUFLOW model cell size (this is because the spacing of the input points is every half cell); and
   • Set an output layer if you wish to keep the resulting raster layer
   

   
   

5. Select OK and the interpolation will be processed, this may take a few minutes depending on the number of points.
6. The grid should appear as below, the colouring can be changed if desired.
   

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