[Radiance-general] ltview, a light source viewer

[Axel Jacobs]

Hi Rob

I've tried ltview with this luminaire (lumen output is prob. wrong, but 
it doesn't matter):

erco.rad:
--
void brightdata erco_dist
4 flatcorr erco.dat source.cal src_theta
0
3 100 0.035 0.0005

erco_dist light erco_light
0
0
3 1 1 1

erco_light ring erco.d
0
0
8
        0 0 -0.00025
        0 0 -1
        0 0.0175

erco_light ring erco.u
0
0
8
        0 0 0.00025
        0 0 1
        0 0.0175
--

erco.dat:
--
1
0 180 37

        3.91061 3.6933  3.25531 2.61173
        1.80559 0.368156        0.157542        0.0374302
        0.0145251       0       0       0
        0       0       0       0
        0       0       0       0
        0       0       0       0
        0       0       0       0
        0       0       0       0
        0       0       0       0
        0
--
The lamp is correctly positioned in the middle of the room, but the box 
looks just grey. No light/shadow is cast by the luminaire. Setting it to 
10 (metric) units doesn't help.

If I use

room.rad:
--
void plastic box_mat
0
0
5  .5 .5 .5  0 0

!genbox box_mat box 10 10 10 | xform -t -5 -5 -5
--

with this view file:
--
rview -vtv -vp 10 0 0 -vd -1 0 0 -vu 0 0 1 -vh 90 -vv 90 -vo 5.5 -va 0 
-vs 0 -vl 0
--
(clip front surface), it works hunky dory: splotch on the floor!

I can't see which one of the default rvu parameters causes this. Could 
be one of the -a* or -d*, but I am not sure...
My feeling is that -av should be set to zero. The lamp might be very 
dim, in which case it's washed out with the ambient. Is it really 
necessary to involve rad? this is done in objview, because you don't 
know upfront how big the scene is etc.

Cheers

Axel