Filtering DEMs (Maritime Charting)

Filtering digital elevation models (DEMs) calculates new z-values for the pixels in the DEM by using an average of the values from the pixels around it. This is important when merging DEMs to smooth the edges where two DEMS come together. The Merge And Filter DEMs tool filters the DEMs that are currently loaded in the map and creates a temporary file that can be used for contour creation.

Learn more about how filter works

Note:

You must have the ArcGIS Spatial Analyst extension enabled to perform this task. For information on enabling the ArcGIS Spatial Analyst extension, see Enabling the ArcGIS Spatial Analyst extension.

Steps:

1. Start ArcMap.
2. Load the DEMs files you want to filter.
3. On the main menu, click Customize > Toolbars > Production Contouring.
4. Click the Merge And Filter DEMs button on the Production Contouring toolbar.

   The Merge and Filter DEMs dialog box appears.
5. Choose Filter Individual Layers in the Operation area.
   Tip:

   You can merge the raster layers by choosing the Merge and Filter Result option in the Operation area.

6. Click the Open button next to the Merging/Filtering Output DEM Workspace field.

   The Choose DEMs Folder dialog box appears.

7. Navigate to a current raster folder.
   Note:

   The folder you choose must be a preexisting DEM workspace.

8. Click Open.
9. Type a name for the filtered file in the Filtered Output Name text box.
10. Check the Apply Focal Majority check box.
11. Type a quantity in the Number of Times to Apply Focal Mean text box.

    The value can be a number between 1 and 5. This represents the number of times the focal mean is applied to the rasters to smooth the appearance when there are two or more rasters.

12. Click OK.