Underground geology

I am new in 3d modeling in CAD and I need some directions/tutorial to learn how to draw subsurface geological layers in the underground of a topography (plain or a hill). It will be my import file for numerical modeling. I can export easily from a GIS a DEM or a STL file of the surface but then I am stuck. All the online materials I found are for modeling buildings on the surface … is there anything else I didn’t find?
Thanks a lot!

Hi Paola -
You will need information about those layers and somehow model them. Conceptually, the abstract idea is to just put several boxes on top of each other. The reality will be a lot more complicated. If the layer thickness were to be uniform all over, you could just copy the surface layer to different depths.

This kind of geological modelling usually uses specialized software like Leapfrog, Micromine, etc. However, you could build a simplified model Rhino. But what kind of data is informing the subsurface model? Do you have drillhole data?

I can start with uniform flat layer, but usually the layer thickness is not uniform, it has it own shape which a I can draw from a geological map. Let’s say if I have a hill and a flat plane dipping on one side of this hill than I need to trim it with the surface. The surface is complex, it’ a real topography then maybe I need to simply it.

Uhm … that is maybe for very complex underground geological modeling

Yes, unless you have a lot of drillhole data or perhaps data from controlled-source seismology, you would want to work with simplified geometry. You could probably use QuadRemesh to make a surface that would be manageable.

If you have a geological map, you could import it as a BackgroundBitmap, trace the geological contacts as curves, and then extrude these curves along the approximate dip angles (if you have them, or can work them out)

thanks a lot, I will try this

Thanks I will try and do this as well, sounds a bit of magic!

Drawing two different surfaces in the same place is a mess because you do not know how they will render. I would draw this geology as surfaces rather than volumes. To make vertical cross-section, I would draw vertical clipping plane and I would extrude curves between the surfaces in the same place as the clipping plane.