[Radiance-general] obj2mesh, UV coordinates and image aspect

[Thomas Bleicher]

This time I have a question about UV mapping:

I tried to export UV texture coordinates from Blender and used
the example from the manpage of obj2mesh to define a texture:

        void colorpict tiled_pat
        7 red green blue mytile.pic . frac(Lu) frac(Lv)
        0
        0

        tiled_pat plastic tiled_mat
        0
        0
        5 .9 .9 .9 0 0

        tiled_mat mesh tiled_mesh
        1 mymesh.rtm
        0
        0

The man page says this works for square images. My image was
a rectangle at first and was converted to a square later, but
both images had the same (wrong) look. I have uploaded two
images (one from Blender, one from rpict) to illustrate the
difference.

http://home.arcor.de/tbleicher/blender/bliff/current.html

My questions now are:

1) What went wrong?
2) How would I define a non-rectangulare image texture?

Please not that I have not checked the quality of the generated
UV coordinates. They are generated by a established *.obj exporter
for Blender and I think they are correct for now. My understanding
of the Radiance texture mapping options is so bad that I expect
the error in the texture definition.


Thanks and have a nice weekend,

Thomas