[Radiance-general] Glass & MTL file troubles... (or how to go from Revit to Radiance with little pain...)

[Jeffrey McGrew]

So I haven't been doing much with Radiance for the last year and a half 
or so, and suddenly something came up at work where it seemed the best 
solution. And actually, I've got a secret plan to make better and more 
widespread use of it where I work (Gensler). My day job is being their 
firmwide Revit guy, and the more folks we got using Revit, the more 
complete and nice models we've got to run design analysis tools on, 
Radiance being one of them.

Anyways, I figured out how to go from Revit to Radiance somewhat-quickly 
by using 3D Studio Max as an $3000 converter. Revit only exports DWG, 
DXF, DGN, and SAT's, and Max is the only 3D application that can import 
those DWG's and leave the Revit materials all intact (so you don't have 
to re-map stuff). So I then export out of Max as an .Obj, grouped by 
material, and I get a nice Radiance-ready OBJ file. Or so I'd hoped. 
I've got two issues, and I'll start with the first big one:

1. Revit likes to model glass as a solid plate, not a flat surface. So a 
bit of glass is a rectangular solid, not a flat plane. So when I try to 
make the windows into Illum's so that they spread light into the room, 
I'm getting errors and problems because I think it's looking for a flat 
plane with the normal pointing into the building. How important is it to 
have the Windows be a lightsource for interior renderings? Is there some 
way, via Mkillum or something, that I could quickly work around this 
issue? I can flatten the glass in Max, but that's an extra step and one 
that seems to also cause issues with zero-area light surfaces.

2. When I export out of Max, I get a .OBJ and a corresponding .MTL 
materials file. I currently use Grep and such to pull out all the 
material definition names out of the RAD file I get from OBJ2RAD, and 
then creating the .MAT radiance material file by hand. I'd love to hear 
a way to take the exported .MTL file and turn it into a starting point 
for my .MAT (short of having to write my own tool to do so...).

Now, we're just designers, and looking for design feedback not hard 
numbers. We'd be happy with something somewhat-accurate, for if/when we 
need 'real numbers' we'll typically turn to a lighting designer who know 
how to generate accurate numbers. But I figure, heck, we're generating 
these models anyways, why not try to put that to better use?

And sorry for the long post. As payback for all the help I've gotten 
here by lurking over the years I'll answer any Revit questions you might 
wanna ask...

Thanks everyone!

Jeffrey