[Radiance-general] Formatting Geometry in Rhino to use genBSDF

[Stephanie Truong]

Thank you so much, this was great help. 

Best,

Stephanie Truong
DOSU | studio architecture
408.387.9112 

On 2017-02-06 21:20, Greg Ward wrote:

> Actually, Stephanie is correct -- genBSDF is one of the few Radiance programs that takes MGF input directly.  I supported this feature because the XML format can incorporate the MGF description as a supplement to the computed BSDF.  However, the MGF is also converted to Radiance before computing the actual BSDF, so ultimately, that is the description that matters. 
> 
> In this case, both MGF and Radiance are equally capable of representing your geometry, which is to say, neither one can do it exactly right.  The NURBs must first be converted to polygons before it can be used, since Radiance does not have a NURBs primitive.  For this operation, you should probably prefer to export in .OBJ format and obj2rad, which will preserve the vertex normals.  Use a fine enough subdivision size that the individual polygons don't undermine your geometric accuracy.  Think in terms of equalling manufacturing tolerances.  You will want to re-describe your materials in native Radiance, however. 
> 
> I hope this helps. 
> -Greg 
> 
>> FROM: Germán Molina Larrain <germolinal at gmail.com> 
>> 
>> DATE: February 6, 2017 7:21:20 PM PST
> 
> Hello Stephanie, 
> 
> First, I want to clarify that genBSDF uses Radiance format as input, which is not the same as MGF. Actually, MGF is a format with some really cool features, but rarely used (unfortunately?). 
> 
> Anyways... Any tool that exports Radiance or MGF formated geometry (which is also readable by Radiance) is useful for generating input for genBSDF. That said, I do not use Rhino, but probably DIVA and Honey Bee or Ladybug can help you on that. Otherwise, there are some SketchUp plugins for exporting Radiance geometry,  which is a tool that allows importing several 3D formats. Finally, I have read several times about Radiance using .OBJ through obj2rad program. I understand that this format is also common, but not suited to model physically realistic materials.  
> 
> So... I think you have several choices. I am pretty sure all these formats are able to model any required geometry, and that the choice you make will be a matter of how easy is to "draw" it. 
> 
> Regarding how to input this geometry into genBSDF, you have to place the width of your "window" along the X axis, Height along the Y axis and inside is towards Z axis (i.e. Up). Any geometry over the Z axis is inside the space and will emit a warning. Read the tutorials for more information on this! 
> 
> I hope it helps 
> 
> best, 
> 
> Germán 
> 
> El 6 feb. 2017 23:07, "Stephanie Truong" <stephanie at dosu-arch.com> escribió:
> 
> Hi, 
> 
> I am attempting to run genBSDF, and was wondering if there is a workflow that allows the use of Rhino/NURBs geometry to convert into MGF format? Ultimately, I am trying to create a BSDF.xml file of a complex shading system. The system is made up of small units which are doubly curved, gradated (depending on orientation to the sun), and symmetrical on one axis. I am unsure if the MGF format is able to model that type of geometry, so it would be helpful to understand how to model geometry to input into the genBSDF command. Let me know if I need to clarify or provide more information. I'm relatively new at this, and any help would be appreciated!  
> 
> Thank you in advance,
> 
> Stephanie Truong
> DOSU | studio architecture

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