Hi, community!

I have not found any solutions to this problem in FME. The problem is to create underground terrain surface for each polygon class (such as clay, sand or gravel in this case <MRR, MRR, KM and MKM). 

Polygon classes have different z coordinate (from 1.8 to -8.7) and the colors represent their classes. I want to find a way to merge/dissolve the nearest polygons in the z coordinate (begin from the top) of each class to create terrain surface, see image below.

For example, the gray color (see image below) should find the nearest gray color within a z range of 0.5 m or auto, and the next gray color should find the next closest gray color downwards and so on.

If a green color is between two grays, the upper gray will stop merging/dissolving on the lower gray. The same process now begins for the lower gray to search downward for the nearest gray color and so on. Once the different polygon classes have been merged/dissolved, they should not overlay or cross each other. 

Appreciate your help and thanks!