The following example shows how to create sightlines for visibility analysis using the Terrain module. In this example 3 view points are analyzed. The view locations are located off shore and the viewed cut block (polygon) is on the side of a mountain.

 Step 1.

 A digital contour map (including elevations at each point) is imported into the Terrain module. A feature representing the cut block is created. The view points and sightlines are also entered. Each view point has 3 sight lines (to the left, center and right of the cut block).

 
Figure: View Positions, Sightlines and the Cut block - Click to Enlarge

Step 2.

The sightlines are created as features without elevation ("draped features"). Their elevation will be determined by draping them over a TIN model created from the contour information. However, the view points are in the ocean so we need to extend the TIN surface into the water. To do this, we create an artificial feature behind the view points. This feature ensures that triangles will be formed from the shore across the water.

Figure: Artificial Feature used to Create a Water Surface - Click to Enlarge

 Step 3.

 We now create a TIN model using the menu Edit - Calculate Terrain model.

 
Figure: Plan View with Triangles Displayed

Step 4.

To complete the project, we can simply display each draped feature in a Profile window, print it out and draw a sight line on it.

Figure: Sight line ground profile displayed in a profile window.

Step 5.

However, with a little extra work, an output sheet can be created (with the sight line included).

Using the same technique described in example Creating a geological section by cutting and pasting from the Windows Clipboard , we select a sightline feature and copy it to the Windows Clipboard using menu function Edit - Copy to Clipboard - Selected Features. The Terrain file is then cleared and the sightline is imported from the clipboard using menu File - Import - Fence Section Projection (see example). This will convert the 3D sightline to a profile in the plan window.

The line of vision can now be added by simply creating a straight line new feature. Repeating this process for the other sightlines will yield the output shown below.

 
Figure: Sightlines projected to fence sections and displayed in the Plan Window - Click to Enlarge

Para retornar a página principal de Softree-Espanol

Contactenos:
Teléfono:
Fax:

Info@softree-espanol.com
(250) 337-5880
(250) 337-2063