Viewshed

Applicability:

• Cadcorp SIS Map Modeller
• Cadcorp SIS ActiveX Modeller            

Ribbon Group:

Analysis-Grids

Conditions for use:

• Item Class: Grid
• Minimum number selected: 1
• Minimum item status: Hittable

Associated commands:

• Create Points
• Create Polygons
• Create Shadow
• Grid From Expression
• From QZone
• KDE Hot Spot
• Range QZone
• Scatter Grid
• Slope commands
• Viewshed

Description:

 Viewshed calculates a 'viewshed' over Grid Items.

A Viewshed is the area that can be seen from a particular 3D location. For example, you could calculate a viewshed to determine how many residents in an area would be able to see a proposed wind generator. SIS can calculate viewsheds for Digital Terrain Models (DTM) or grid items.

To create a viewshed:

1. Select a DTM or Grid item.
   
   
2. Select Viewshed.
   
   
3. Click the location for the viewpoint in the map window.
   
   
4. Complete the Create Viewshed dialog entries as follows:

Height above ground

The height above the snapped point from which to calculate the Viewshed.

Radius

The radius of the viewshed.

Create as Grid

The result of the Viewshed calculation will be one Grid item for each of the source Grid items.

Create as QZone

The result of the Viewshed calculation will be a single QZone item.

Add origin Point item

Check the tickbox to create a Point item at the origin of the Viewshed.

5. Click OK to create the Viewshed item.

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