The Esri TinPolygon component.
TinPolygon is a non-creatable object. References to non-creatable objects must be obtained through other objects.
A TinPolygon is an areal feature imbedded in a triangulation. It is defined by a set of contiguous triangles, or a ring of edges, that share like properties. These properties are set using one of the TinElementFilters. Triangles or edges that have properties compatible with the filter are considered part of the set. TinPolygon objects are created via ITinAdvanced.ExtractPolygon.
Different types of filters can be used to define a TIN polygon. Some come provided by 3D Analyst. Others can be custom made. Stock filters that support TIN polygon definition include TinValueFilter, TinTriangleFilter, and TinEdgeTypeFilter.
In addition to a filter, a TIN polygon needs a location which is specified using a seed triangle or edge. The seed and filter are used together to dynamically discover a polygon. When the software extracts a polygon it starts with the seed and uses the TIN's topology to search outward. Any triangles or edges neighboring the seed and pass through the filter are added to the set. Their neighbors are examined in turn. This continues iteratively until no more elements are found.
Enforced edges (i.e. hard and soft breakline edges) can be used as barriers, or constraints, to the outward search when the seed provided is a triangle.
A TinPolygon defined using a triangle seed may comprise just one solid filled area or be more complex with interior islands. In either case, it can have only one exterior boundary.
A TinPolygon defined using an edge seed can have no islands. It can have only one exterior boundary.
Extended Error Information
Use the ISupportErrorInfo method InterfaceSupportsErrorInfo to determine if the object supports extended error information. If the object supports extended error info, VC++ developers should use the OLE/COM IErrorInfo interface to access the ErrorInfo object. Visual Basic developers should use the global error object Err to retrieve this extended error information.