Expand contract surface

You can use this function to expand or contract a surface by a set distance. You can also use the function to create a valid solid by expanding both sides of a surface and closing it.

To run this function: Choose Surfaces > Mesh tools > Expand/Contract, or...

In the Function Chooser, type MESH DTM EXPAND, and press ENTER.

To run this function: Choose Surfaces > Mesh tools > Expand/Contract.

Fields on the Expand/Contract solids form

Field	Description
Selected surfaces
Active layer	Display only. The current active layer that contains the surface.
Object Range	The objects that you want to expand. If you leave this field blank, all objects in the active layer are expanded or contracted.
Trisolation Range	The trisolations of the object that you want to expand. If you leave this field blank, all trisolations in the active layer are expanded or contracted.
Select button	Allows you to select the objects and trisolations that you want to expand or contract in Graphics.
Settings
Expansion distance	The value by which you want to expand or contract the surface. Positive values expand the surface. Negative values contract the surface.
Expand/Contract	The method for expanding or contracting the surface. Options are: Single side of surface: If the Expansion distance is positive, the surface is expanded above the surface. If the Expansion distance is negative, the surface is contracted below the surface. Both sides and close as solid: The expansion or contract of the surface occurs on both sides of the surface, and the new surfaces are joined to form a solid.
Precision	The degree of accuracy between the shape of the solid being expanded or contracted and the new solid. The more precise the expansion or contraction, the greater the number of triangles in the new solid. Note: The higher the precision, the more time and memory is used for the expansion.
Output
Overwrite existing objects	The expanded or contracted surface replaces the original surface in the layer.
New layer	The expanded or contracted surface is created in a new layer. If you select this option you must type a name for the new layer.
Simplify results	Selected: The number of triangles in the new surface is reduced. The position of the slider determines the degree to which the triangle number is reduced. Min removes the least triangles, Max removes the most triangles. Cleared: The number of triangles in the surface is not reduced.

Output

The expanded, or contracted, surface is displayed either in the current layer, or in a new layer.

Troubleshooting

The precision value that best suits an expansion or contraction depends on the nature of the surface you are modifying. If the surface created contains holes, or you are not satisfied with its shape, increase the precision value. If you are satisfied with the shape but the new surface contains too many triangles, decrease the precision value.