Fill polygons

A fill polygon tags an area with an attribute value so that the TIN can be symbolized by this value. The attribute must be an integer. Fill polygons are used to represent continuous surface features like land cover and land use or discrete features like flood zones or endangered species habitats.

Top: A TIN symbolized by elevation. Bottom: A continuous polygon layer of vegetation has been added as fill polygons. The TIN is symbolized by vegetation code.

Like other surface features, fill polygons cause the TIN to be retriangulated.

Top: The polygon layer will be added to the TIN as fill polygons. Middle: The TIN is retriangulated. The blue lines, indicating polygon boundaries, become triangle edges. (They look wavy, but they are straight line segments.) Bottom: The TIN is symbolized by the polygon attribute values.

Tag values

Using fill polygons is not the only way to assign integer values to triangle faces. You can also assign them by specifying a “tag value” field from the attribute table when you add, replace, or clip polygons.

You can also assign integer values to triangle nodes by specifying a tag value when you add mass points. Tag values cannot be used with breaklines or erase polygons.