[Radiance-general] Lighting from a light probe

[Kirk Thibault]

One of the first things to consider is your "up" vector.  Debevec uses 
Y up in hs <angmap.cal>, Radiance defaults to Z up.  This is easily 
changed in the Debevec <angmap.cal> file by simply replacing the 
coordinate (x,y,z) references consistently in the angmap.cal file (see 
Debevec's comments in the <angmap.cal> file for an explanation of the 
direction convention).

It sounds like you are trying to light the image with a light probe and 
also include polygons in the scene that will appear as the synthetic 
"room" (floor, ceiling, and 4 walls [N, E, S, W]).  You may have better 
luck generating a "cross" format probe, then taking each of the six 
cross segments and individually mapping them to the walls of your room. 
  Then give each of the polygons the glow and let the HDR-images on each 
of the six "room" polygons illuminate your interior scene.

Does that make sense?  it may be easier to try by using one of 
Debevec's cross probes on his site and xforming it appropriately so 
that the correct segment fills each of the six room polygons - once 
this is done you can try illuminating your Rad. scene with it.

Fun!

kirk

On Jan 27, 2005, at 11:18 AM, Tarik Rahman wrote:

> Hi
> I'm trying to light a room with the light that's irradiated onto a 
> mirror sphere
> in order to insert synthetic objects into the room. In radiance I take 
> a close
> up .pic of the mirror sphere and convert it to a light probe using 
> HDRShop. Do
> I use same code as in Debevec's tutorial, you know
> void colorpict hdr_env
> 7 red green blue lp_smallMirr.hdr angmap.cal sb_u sb_v
> 0
> 0
>
> hdr_env glow env_glow
> 0
> 0
> 4 1 1 1 0
>
> !genbox env_glow room 50 30 50 -i | -t 2.5 2.85 2.5
>
> for the lighting? Will angmap.cal work for any light probe or do I 
> have to write
> my own because when I render this, the reflections from the light 
> probe aren't
> mapped onto the walls of the room properly?
>
> Thanks for any help
>
> Tarik
>
>
> --
> Tarik Rahman
> PhD student, Institute of Perception, Action and Behaviour
> School of Informatics
> University of Edinburgh
>
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