Triangulated Irregular Network (TIN) in ArcGIS

A TIN is a network of triangles with each triangle having a slope gradient and direction. You can generate a TIN from a an elevation rarset, point, line or polygon 2-Dlayers or 3-D shape files.

TINS have several advantages over elevation rasters:
1) The surface model is more efficient and accurate because large triangles are produced for areas that have little terrain variation while many small triangles are produced to represent areas with high terrain variation.
2) TINs can be built with breaklines. A breakline is where there is a sudden change in slope….examples might be a line layer of ridge roads, a line layer of streams, a polygon layer of lake shorelines, etc.