Dear List,
I have problems getting trustworthy irradiances in a scene where I am using a 180 degree light source as a sky dome. For testing purposes I have created the following very simple setup: a groundplane with normal (0 0 1), and a 180 degree source with direction vector (0 0 1), the radiance of the source is RGB=(1 1 1) (unity radiance). I set the camera to look straight down on the groundplane and render using rpict -i to get irradiances. In theory such a source should result in an irradiance at the groundplane of exactly pi, but when I render I get approx.RGB=(4.77 4.77 4.77)
Any ideas for explanations? Any ideas for how to correct this?
Best,
Claus
The scene.rad file:
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# Materials
void plastic perfectlambert
0
5 1.0 1.0 1.0 0 0
#Geometry
!genbox perfectlambert groundplane 10000 10000 0.5 | xform -t -5000 -5000 -0.25
# Illumination environment: a 180 degree unity radiance skydome
void light skyradiance
0
3 1 1 1
skyradiance source TheSky
0
4 0 0 1 180.0
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The render parameters:
rpict -i -x 1024 -y 1024 -ab 4 -aw 1 -ps 1 -dt 0.0 -dr 3 -dp 8192 -ds 0.01 -dj 0.9 -dc 0.8 -u -vf scene.vp
And the scene.vp file:
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rview -vtv -vp 0.0 0.0 10.0 -vd 0.0 0.0 -1.0 -vu 0 1 0 -vh 45 -vv 45
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