Terrain Grading Function

Merge Function

	This Merge function allows you to merge the TIN surface from one Terrain into another. The source file terrain must have a TIN model. After the Merge is complete the combined TIN model is easily recreated.
	Merge works as follows: 1) The boundary of the TIN model from the source terrain is extracted. 2) All features withinn the destination terrain are clipped to the boundary determined in 1. 3) Features from destination terrain (within the boundary) are merged into the destination Terrain.