formZ and Radiance

Hi Randolph,

OBJ is the way to export from formZ to Radiance by way of the obj2rad
translator. We have gone this route for many years. If you want
smoothing on curved surfaces, you have to make sure that you ask for
surface normals to be exported in the obj export options dialogue. I
recommend that the formZ model be broken up into layers and that you
export these one at a time. This allows you to isolate problems if there
are some. For example, in a recent case where I exported surface
normals, there were some lines in the obj files where the surface
normals had 0 for the x, y , z components. obj2rad did not like that. I
also seem to recall that holes in polygons, like windows, will cause
Radiance to fill the opening on rendering. You have to split the
offending polygons before exporting. This is not hard to do in formZ.
Another issue to note is that, if you are working in metric units in
formZ, formZ will multiply sizes by multiples of 10 depending on what
units you are using (for meters the exported sizes are 100 times
larger). It is best to do a test translation and to look at the obj file
to check by what factor the dimensions have been multiplied. You can
then compensate by applying a scale factor in the export options under
transformation. Also, under transformations, uncheck the default
flipping and swapping of axes.



Message: 5
Date: Fri, 2 May 2003 18:55:43 -0700
From: Randolph Fritz <[email protected]>
To: [email protected]
Subject: [Radiance-general] FormZ & Radiance
Reply-To: [email protected]

What are people's experiences with FormZ and Radiance? I've got a
school studio project which I would like (if there is time) to do some
lighting studies on (yes, the one with the shoji) & it's currently
modelled in FormZ. Last time I tried that I used OBJ format as a
Radiance export method. What do people think--is that the way to go?


I forgot to mention that there is a convenient way for dealing with
material colors when exporting to Radiance by way of obj files and the
obj2rad translator. Before exporting make sure that, in the export
options dialogue for obj, the material option is set to "wrapped" rather
than "off". This will produce a materials file (.mtl extension) which
contains parameters for each surface style (=material) in formZ. This
files is exported with the .obj file. If you name the surface styles you
actually use in formZ (rather than leaving them as style_1, style_2
etc.), you can easily identify the surface styles that you will need in
the Radiance material file. The red, green, blue values for each
material are the three numbers after the kd parameter for a material in
the .mtl file. These can be used directly in the Radiance material file
and will produce colors that correspond closely to those that appeared
in formZ renderings (barring differences in monitor calibration).