How To: Create a subset of a Digital Elevation Model based on a specific elevation range
In some cases, when using a digital elevation model (DEM) for an analysis, a subset of the DEM must be created based on a specific elevation range. For example, an area that falls between 1400-2000 meters may be extracted from the original DEM for further data processing or analysis.
The instructions provided describe how to create a subset of a DEM based on elevation by using the Raster Calculator tool in ArcMap or ArcGIS Pro.
Note: These steps require the Spatial Analyst extension license to be active and the Spatial Analyst toolbar to be turned on.
- Add the DEM to the data frame.
- In ArcMap, click Add Data on the Standard toolbar. Browse to the DEM raster data, and click Add.
- In ArcGIS Pro, open a new blank project. Under the Map tab, click the Add Data drop-down, and click Data. Browse to the DEM raster data, and click OK.
- In ArcMap's ArcToolbox side panel or ArcGIS Pro's Geoprocessing panel, navigate to Spatial Analyst Tools > Map Algebra > Raster Calculator. Double-click to open the tool.
- In the expression box, type the expression to specify the elevation range for the subset of the DEM. For example, to create a subset of a DEM with the elevation range of 1400 to 2000 meters, type the expression below:
Con(("demName" >= 1400) & ("demName" <= 2000), "demName", 0)
Note: In the above expression, 'demName' is the original DEM layer in the data frame. For more information regarding 'Con' expressions, refer to following web help document: ArcMap Help: Con
- Set a name and location for the Output raster, and click OK/Run.
- A new DEM raster (with elevation = 1400-2000 meters) is created. Cells that are not within the specified range receive a 'false' value (in this example, 0) in the output raster.
- To improve the visual contrast, remove the black area created in the output raster where the cell values are zero and change the symbology for the cells to No Color.
- In the Table of Contents, right-click the newly created layer and select Properties.
- In Layer Properties > Symbology > Stretched > Display Background Value, click the check box and set the value to 0. Set the color as No Color.
- Select the stretch type in the Type drop-down list. For example, Percent Clip is selected in this article.
- Click Apply > OK.
- In the Table of Contents, right-click the newly created layer and select Symbology.
- In the Symbology panel, in the first drop-down list, select Stretch.
- Under the Background section, check the Display Background Value check box and set the value to 0. Change the color to No Color.
- Under the Stretch section, in the Stretch type drop-down list, select Percent Clip. For more information about the stretch function in ArcGIS Pro, refer to the following web help page: ArcGIS Pro Help: Stretch function.
- ArcMap: Using Extensions in ArcGIS
- ArcMap: Conditional evaluation with Con
- ArcMap: Stretching a raster to improve the visual contrast
- ArcMap: Stretch function
- ArcGIS Pro: Enabling the Spatial Analyst extension
- ArcGIS Pro: Con
- ArcGIS Pro: Stretch function
- How To: Limit the values of a raster with Spatial Analyst