[Radiance-general] import to Radiance

[Jack de Valpine]

Hi Jia,

Here are a few additional pointers on obj from revit.

NORMALS
For whatever reason it seems that fbx converted to obj using the FBX 
converter can for some normals report:

    vn 0 0 0

which make obj2rad unhappy.

So the best thing that I have found is generally to take the convert 
fbx->obj file and process it through something like Rhino, Polytrans, 
NuGraf, or Blender (other suggestions out there...). Which have 
functionality to recalculate normals and otherwise process meshes/polygons.

MATERIALS
First off as I believe some others have pointed. Material information 
from other programs is useless! They do not report valid reflectance 
information. The only thing that you should hope to get is that the 
geometry is organized by material name.

A stock conversion from fbx->obj will for what ever reason organize 
geometry by object name! This is despite the fact that there is a valid 
usemtl statement in the obj file. This can be ok however it does mean 
that you probably need to have some kind of parser to do some material 
mapping in a useful way (there can be hundreds of object names). I did 
this in perl early on in my experience processing Revit models into 
something useable by Radiance. However, this all can be better managed  
by processing the fbx->obj file through Rhino, Polytrans, NuGraf or 
Blender where you can process the file and send out an obj with normals 
and material groupings that make you and Radiance happy.

Best,

-Jack

-- 
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction



Jia Hu wrote:
>
> Hello all:
>
>  
>
> Thanks to many suggestions and help from this group, I tried some 
> approaches of importing files to Radiance. I hope to share my 
> experiences and also want to know if anyone knows how to solve the 
> questions bellow.  First of all, sorry for such a long email.
>
>  
>
> To import models to Radiance, there are three basic ways (obj, dxf and 
> ecotect) (There are others, but I just know the following three):
>
>  
>
> *(1) **The following uses obj2rad:*
>
>        (a) Convert to *.obj* file by other tools,
>
>    (b) Then use *obj2rad* to convert the *obj* file to .*rad* file;
>
>    (c) Define materials in another .mat file (material names could be 
> found in the objfile.data by using command: obj2rad -n objfile > 
> objfile.data)
>
>  
>
> *(**2**)** The following uses dxf2ad*
>
>     (a) In revit, export .dxf file (save as *autocad 2000* rather than 
> current version),
>
> (b) Then use *dxf2rad* to convert the .dxf file to .rad
>
> But I found all the geometries get the same materials.
>
> So, does anyone know how to handle this problem?
>
>  
>
> *(3)  The following uses Ecotect *
>
> (a) Export .dxf file from Revit (I can not import dwg by Ecotect, is 
> that normal?)
>
> (b) In the diag, define different zones *by item name;*
>
> (c) Export the model into .rad file directly, including .mat file
>
> The problem is that .mat file seems not correct. One material is 
> assigned to one zone. For example, in the Door object, there are two 
> types of materials, but they are combined into one material after 
> importing to Ecotect.  
>
> So does anyone know how to deal with the materials problems?
>
>  
>
> For the above methods (1) and (2),  the key is to get .obj and .dxf 
> file. To get .obj file, there are 4 ways;
>
> *(1) In revit, use FBX converter to get obj file*
>
> (a) In revit, export fbx file;
>
> (b) Download FBX converter at URL: 
> http://usa.autodesk.com/adsk/servlet/pc/item?siteID=123112&id=10775855 
> <http://usa.autodesk.com/adsk/servlet/pc/item?siteID=123112&id=10775855>
>
> (c) Convert fbx to .obj
>
> The problem is that I always get some zero value of  “vn” in obj file. 
> Even if I use “–f” option or delete “vt” “vn”, it still does not work 
> because the “face” in obj file uses “v/vt/vn” format.  If I delete 
> them, errors appear because obj2rad can not find “vt” and “vn”. Could 
> anyone know how to solve this problem?
>
>  
>
> *(2) Use 3D max to get obj file*
>
>    (a) In revit, export fbx file;
>
>    (b) Import fbx file to 3ds max
>
>    (c) Make some changes in 3ds max to get export obj file.
>
> I have not tried this way, but I think this way is better because I 
> can re-assign or change materials in 3ds max easily and can get the 
> correct material names. Is this right?
>
>  
>
> *(3) Using 3ds max to get obj file*
>
>    (a) In revit, export dwg file;
>
>    (b)  Import dwg file to 3ds max;
>
>    (c) Assign materials in 3ds max
>
>   You can see it at  http://www.becausewecan.org/node/190    Should I 
> assign materials again in 3ds max?   I have not tried this way, but it 
> seems good as (2).
>
>  
>
> *(4) using sketchup pro to get obj file. *
>
> ** 
>
> As always, thank you all.
>
> Jia
>
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