[Radiance-general] Transparent textures (again)

[Axel Jacobs]

Dear all,

this was discussed here
http://www.radiance-online.org/pipermail/radiance-general/2004-July/001926.html,
but if there was an answer that I understand, I missed it.

I am working on the advanced tutorial again.
Created a falsecolor picture of the working plane illuminance in a room
following John M.'s technical note number 2 here
http://www.radiance-online.org/pipermail/radiance-general/2002-September/000405.html

See the tutorial for details:
http://luminance.londonmet.ac.uk/learnix/files/phatfile/radcourse_advanced.pdf

I would like to map the falsecolor illuminance image back into the room
onto a new surface at working plane height to make the result more
understandable. For this, the background of the falsecolor contour line
image should probably be black, but this is no problem. The false colour
lines would appear to be hovering in the room. I saw something similar in
a demo of some commercial lighting software, but don't remember where.

I think my problem is the cal file (PAB named his one picture_UV.cal)
which is often referred to, but never given as an example. Since my object
is a nice'n'easy plane, would it be possible to use picture.cal that comes
with RADIANCE?

Those are PAB's words of wisdom:

--------------------- 8< - Schnipp -----------------

void plastic mp1
0
0
5 .01 0.01 0.01  0.35 0.1

void glass mp2
0
0
3  .9 .9 .9

void mixpict mp
15 mp1 mp2 digital1 sp.pic picture_UV.cal tpic_u tpic_v ...
0
0

--------------------- 8< - Schnapp -----------------

Could somebody explain the mixpict primitive a bit more?

Cheers

Axel