Is it possible to generate a DSM using a Sketchup model in Global Mapper?

Fi_LArch

Hi all

I'm new to Global Mapper, and beginning to figure out how to use it for Visual Studies in urban areas. South Africa does not seem to have LiDAR / LAS data available in Open Source or otherwise, as so I must make other plans.

I need to generate a viewshed for a proposed development in Cape Town, that takes into consideration trees and buildings as visual barriers. Ideally, I would be able to export a Google Earth-esque 3D-buildings layer dataset that reads buildings and trees as visual barriers. But it seems that this is fiercely guarded proprietary information. 

So. Is there a way in Global Mapper (and/or using other programs and plug-ins) to create a Digital Surface Model from a 3D model built in Sketchup?

Any help or tips would be greatly appreciated.