Analysis Options

Use this dialog to set options for terrain model analyses.

Where can I find the dialog?

In the toolbox for Planning, Design, and Execution in the terrain model drawing, select Create thematic map (landscape analysis)...

Remove Triangles with Sharp Angles Along Island Edges

With the options Remove triangles smaller than (for example, 30 m²) and Remove triangles with angle less than (for example, 35 degrees), the program attempts to remove triangles that are "peaks."

Note

This applies to individual triangles, not islands. The program searches for sharp triangles that have two sides neighboring another and the same interval, and the third neighbor is the same interval as the triangle itself.

Example of cleaning up sharp angles

Triangle with sharp angle before cleanup

If the angle at the point of interest is less than specified, and the triangle's area is less than specified, this triangle will be moved to belong to another interval.

Triangle after removing sharp angles

Info

The triangles have been moved to another interval, removing unnecessary noise from the result.

Analysis Process

The analysis proceeds as follows:

1. Each triangle within the boundary polygon is assigned its value (slope, sun/shade, etc.).
2. The triangles are grouped into their interval, and within this level, further grouped into islands:
3. If triangles share edges with other triangles, they are added to the same island.
4. A new triangle added to an interval can connect islands.

After this process, an unfiltered result may look like this:

Unfiltered analysis result with many small areas

Clean Up Small Areas Without Interest

With the option Remove island polygons smaller than (for example, 50 m²), you can clean up the result. The islands in each interval are reviewed from smallest to largest area, and if the area is below the specified value, they are merged with an island in another interval. The longest triangle edge neighboring another interval determines which interval and island it should be connected to.

Example of cleaning up small areas

Result before cleaning up small areas

Result after cleaning up small areas

Info

The island polygons have been moved to another interval, removing unnecessary noise from the result. With this option, you can avoid capturing too much variation within an area.