[Radiance-general] REVIT to Radiance pipeline

[Christopher Rush]

I typically do what Randolph does, exporting to DWG and using Rhino to assign materials and convert to OBJ. A shortfall of this is that you get an exported DWG organized by layers, and possibly loose or confuse some material assignments from Revit in the process. There is an option in exporting the DWG from Revit to export options by one of the layering standards but with overrides for each unique property within a layer (getting layers like A-WALL, A-WALL-1, A-WALL-2 for different wall construction types).

I wonder if exporting from Revit to FBX preserves some of those materials or construction data for each surface more directly than the layer organization. I haven’t had luck with the FBX export workflow in the few times I tried it (long ago). The FBX file standard might remain more standard and stable with each new release of Revit because I think it’s meant to be something like a parallel to DXF (DWG is to DXF, as RVT is to FBX in my mind, but I could be wrong).

If we all were interested in making the first workflow more open source (aka less costly), could probably do the same with Blender (in lieu of Rhino or Max). But that’s still relying on DXF or DWG and the possible loss of material information. However the material information directly in a Revit model is probably not to be trusted anyway. Just because something is assigned “paint type 1” or whatever it might be, doesn’t help decide the material.

For possibilities of automation, etc., a strength of Rhino is that RhinoScript (and maybe Grasshopper) give a scripting possibility to do things like flatten glass assemblies in that software. I guess the same could be said for Sketchup and Ruby, but Rhino seems to be more prevalent with architects these days. Maybe the same could be done for Blender but I’m not particularly familiar with scripting possibilities in Blender.

-Chris





From: Randolph M. Fritz [mailto:rmfritz3 at gmail.com]
Sent: Friday, November 13, 2015 9:06 AM
To: Radiance general discussion
Subject: Re: [Radiance-general] REVIT to Radiance pipeline

Now, when I did this, I ended up using the export to DWG and working on the resulting model in Rhino; a colleague did the same with SketchtUp.  The general problem I found with exports from Revit is that one gets hugely more information than one needs, resulting in a large and unwieldy model which must be simplified for effective simulation. For simple models, sometimes it is easier to refer to plan and section drawings and rebuild the model entirely!

An excellent custom exporter is most likely possible. Revit keeps a huge amount of information about the details of its models, and it seems to me that in principle it is possible to do a thorough and accurate Radiance export of any part of a Revit model. Revit exposes some of its internals with a Python interface, and there are also tools like BIMlink (Ideate Software) which provides access to Revit's internal databases through Excel. However, developing dedicated Revit <-> Radiance export tools seems to me likely to be expensive and hence would probably have to be done as a commercial product. At least, I wouldn't want to try it without good funding — extensive knowledge of Revit would be required, and that information is not available for free.

--
Randolph
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