Viewshed

+ This tool requires a Pro license

A viewshed is an analysis that shows all of the locations that are visible from a given point, or likewise, all of the locations that can see the given point. Using a loaded elevation grid layer and a selected point feature as the transmitter location, a viewshed analysis can be completed in Global Mapper Mobile. With options to set the view radius, transmitter height, and receiver height, the viewshed process results is a new raster map layer containing area features for the visible or hidden viewshed area.

Note: A point feature must be selected with the Digitizer tool prior to selecting the Viewshed tool from the Toolbox.

Viewshed Options

Radius - The radius, specified in meters is the distance from the selected transmitter location point Global Mapper Mobile will analyze visibility.

Start Angle - The start angle specifies the cartographic angle at which the radial subregion for the viewshed begins. This angle is a cartographic angle, meaning that 0 degrees is north and angles increase clockwise.

Sweep Angle - The swept angle specified the number of decress clockwise from the start angle to include in the viewshed. The defaults of starting at 0 degrees and sweeping through 360 degrees will perform an analysis over the entire area.

Transmitter Height - Specified in meters, the transmitter height is the height above the terrain of the transmitter point.

Receiver Height - Specified in meters, the receiver elevation notes the minimum height above the ground from which the transmitter must be visible for the point to be considered visible.

Display Hidden Areas - If enabled the viewshed layer will show areas that are NOT visible based on the input parameters. To create a layer showing visible areas, leave this option disabled.

Steps for Viewshed Creation

  1. Enable to Digitizer tool from the Toolbox.

  2. With the Digitizer Select tool enabled, tap to select a point feature in the map. The viewshed will be calculated using the selected point as the transmitter location.

  3. From the Toolbox select Viewshed.

  4. On the Viewshed Setup screen, enter the viewshed parameters (listed above). Any height values are height above the loaded terrain layer. The toggle to display hidden areas can be enabled to create a veiwshed layer highlighting hidden areas of instead of visible areas.

  5. Tap OK to create the new viewshed layer.

  6. The viewshed layer will appear in the map and the layer description will be Viewshed by default. The layer description can be changed using the layer options accessed through the Control Center.

    Note: A created viewshed layer is for field reference only and cannot be saved to a Global Mapper Mobile Package file (*.GMMP).