Creating and using clutter data from satellite imagery

The process of creating Land Use/Clutter grid data is a two-step process in which you’ll first draw clutter areas as polygons on the map and save those polygons into a single .BNA file, then use the ‘create land use (clutter) datafile’ function to create a .GCV grid file from the polygons. This .GCV grid file is what you’ll point to as the clutter database.

Note that the process is different if you’re trying to modify, or “carve”, new polygon or polyline areas into an existing .GCV clutter file. The steps outlined below are for creating a new clutter grid file from scratch.  

 

  1. Create a folder in your project to store the clutter polygon and clutter grid files.

  2. Go to ‘Databases -> Land Use (Clutter)’ and make sure that the project is pointing to your desired clutter attenuation file. You may want to make a copy of the attenuation file and put it within the project folder so it can be adjusted, if needed.

Set the ‘Type’ drop-down to ‘EDX .GCV format’, but un-check the ‘Active’ box and don’t set the ‘Directory Path’ until after you’ve created the grid file.

3. Zoom in on the area of interest and use the ‘Map Layers’ dialog to show the Bing map layer so that you can see the areas you want to create clutter for.

4. Use the ‘Draw -> Land Use (clutter) polygons’ tool to create multiple land use polygons which cover all the areas you want to address.

            -Select the land use type and enter a height value for each new polygon:

-Click points on the map to create the polygon. Double-click on the last point to automatically connect back to the first point and close the polygon. Repeat this to create polygons that define each of the relevant areas.

Bear in mind that you will not be able to add more clutter regions without creating a new .GCV file, so this process is faster and easier if you draw all the clutter regions for a given area in the first stage.

 

5. Once you’ve drawn all the land use polygons for the area, make sure you have them all selected and active by going to ‘Edit -> Select all objects’. This should highlight all the land use polygons you’ve drawn in the ‘EDX Graphic Objects’ map layer.

 

 

6. Right-click on a corner point for one of the polygons and select ‘Save to file’. Save the polygons as a .bna file in the clutter folder you created.

7. Go to ‘Databases -> Land Use (clutter)’ and use the ‘Create land use (clutter) datafile’ section to create a .GCV grid file from the .BNA polygon file you saved in the last step. Make sure the new .GCV grid file gets saved into the clutter folder you created.

Note that you’ll need to set a grid spacing for the file in arc-seconds. One arc-second = ~30 meters.

Click the ‘Create land use (clutter) file’ button once you’ve browsed to the right source polygon and destination .gcv file location. This should create a .gcv file in the specified location.

 

8. Once the grid file has been created you can point to the clutter folder as your active clutter database and add the clutter map layer to show the grid file.