Viewsheds/Weapons Fans

A viewshed or weapons fan is a graphic that shows what can be seen from a particular location, and requires a DEM.

Radial Lines, discrete Radial lines, full coverage

Viewshed algorithms.  There are tradeoffs between speed and accuracy.

If you want to display the viewsheds on an image, the image should share the coordinate system with the DEM used to compute the viewshed.  Failure to follow this will result in problems (misregistration).

A visible area plot may be used for:

Steps for Fans:

  1.   Select icon on  Map Window Toolbar, or use menu choice Calculate, Intervisibility, Viewshed.
  2. Double left-mouse click on the position for the weapon/observer on the map display.  Consider using Verify graphical selection.
  3. Select desired parameters in Viewshed Parameters window. When ready, click on the OK button.
  4. To modify the fan right click and select the "Edit fans" choice from the right click on the map popup menu.
  5. You can draw range circles from the the "Edit fans" choice from the  right click on the map popup menu. Double clicking on a fan's record in the data base, and pick the range circles option.
  6. To save fans or Export fan definitions for use in ArcGIS use "Edit fans" choice from popup menu and then pick "Report" and DBF table.

Vegetation grids can be loaded and used for intervisibility masking.

Outline  fans with sector boundaries, and min/max ranges.

Export fans to ArcGIS or Google Earth. 

Viewshed Validation

Save and restore fans

Multiple fans (especially with multi-cores or multi-processors)

Last revised 12/6/2014