Buffering linear features
The Edit | Modify Selected Feature(s) | Buffer function is a member of the Enhanced Mapping and Drafting functional group. This is only available in demonstration mode in the Terrain Standard and Terrain Shareware products.
This example generates a riparian zone near a stream.
- Select the two stream features (blue with direction arrows).
- Choose menu item Edit | Modify Selected Feature(s) | Buffer. Type in 50m offset and select both Right and left. After pressing OK you will see the following:
- Select Edit | Modify Selected Feature(s) | Break-At Current Feature. When complete press the Delete key to remove overlapping segments.
- Use Edit | Modify Selected Feature(s) | Join and Edit | Modify Selected Feature(s) | Linetype to make the buffer features into one shaded region.
Note that the proposed access road has been moved so that it is never closer than 50m to the stream.
Buffering a closed feature
This example generates the shape and area of a region one tree height (30m) from the boundary of a logging cut block.
- Select the block boundary feature.
- Choose menu item Edit-Modify Selected Feature(s)-Buffer. Type in 30m offset and select Right side (inside of clockwise feature). After pressing OK you will see the following:
- Remove the overlapping segments (note that they are not connected) by selecting and deleteing.
- Use Edit | Modify Selected Feature(s) | Join to make the left lobe into a single feature.
- Use Edit | Modify Selected Feature(s) | Linetypes to change color and hatch.
If the yellow interior features are changed to have negative areas (using Edit | Modify Selected Feature(s) | Properties), the Area Sub-Total field in the Status window can be used to find various areas. To display the total area, select outer boundary only; to display the buffer area, select all three boundaries; to display the interior areas, select only the inner boundaries.