To create a terrain for a building, I was wondering is there a difference in file size/ complexity between Subd and regular Nurbs surfaces? I was wondering whether I should import a mesh as Subd (made with a displacement map) or that the heightfield command would yield better results for terrains created from a geotiff. I will have to ask the IT deparment to install V7 in case Subd creates a lighter surface. What I need to create will probably be around 300x150m surface with a vertex every 0,5m-1m (which is the geotiff’s resolution and allows me to capture ditches in the terrain).
Even at 0,5meter intervals, a 300 x 150 m terrain will create a mesh with ‘only’ about 180K vertices. That’s actually pretty light and will give you all the detail. Using surfaces or SubD will in all likelihood give you either something extremely heavy or lose all your detail.
Making a mesh here with 180K vertices gives me around a 14Mb file.
True to that, I was hoping to go the quick and dirty round by cutting roads and pavement out of the surface with the outlines from a CAD file. To then move the roads down, project curves to the road surface and extrude out road markings for a quick and easy render. Though I guess I’m asking for too much here. Lumion requires the road markings to have a different material, so I’m not sure I can get away with using a texture for them instead.
E: Come to think of it, a texture not possible since I Lumion doesn’t have the tools or node based material editor…
I have never worked with meshes in Rhino, but I should be able to subdivide them and cut them to pieces, right? I could then try quad remeshing it afterwards.
Splitting meshes in Rhino is a horrible experience. I know of no other software that is as bad in that realm. But it can be done if you know the tricks and have the patience.
Some bugtracking trix are
Cull degenerated edges
Spilt disjoined meshes
Move the splitter just slightly
Rebuild the mesh to 99% the size and try again.
(I work with meshes daily in Rhino)
Thansk Holo for the tips! In that case, I also have access to Max, so that could work as alternative solution. Will have to test and see next week I suppose. I may be able to reduce the terrain in size to include areas with higher displacement (the ditches) and leave other areas planar. Then I may be able to work with a heightfield or Subd mesh to maintain smooth curves for the roads.
Plenty of approaches fortunately.
I just did a quick experiment - with one of my ASCII grid test files I created a mesh which is 500 x 500 cells - i.e. 250K quad faces. I converted that to a SubD - I was surprised that it didn’t hang or anything, just took a couple of seconds. I then exported the mesh and the SubD each as Rhino .3dm files and checked the file size. The mesh is 9Mb, the SubD is 99Mb…
Then, as a second experiment, I thought I would try seeing if I could split that subD with just a single freeform curve. Nothing selected, called the command Split, selected the SubD, and then… waited. Didn’t even get a chance to choose the curve, it just hangs here. A few minutes later, the little wheel is still spinning.
So I guess working with a massive SubD instead of a mesh is not currently a viable option…
Edit - wait, it did finally let me choose the curve - after about 5 minutes. So I chose the curve and Enter, and now I am waiting again… 
Edit 2 -
After half an hour of waiting, still not done, so I guess I will give up now…
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Well, it’s one way to slack-off from work. 
That’s clear, thanks!
Thanks for the update!
I think that I’ll create planar surfaces, export high res meshes from these out of Rhino and then conform/shrinkwrap them onto a lowpoly and high poly terrain mesh in Max/ Blender. And probably boolean to create the cuts, quadremesh at the end and that should be it. Let’ s hope these operations stay performant on the high poly terrain 