[Radiance-general] Multiple spherical glow sources?

[Ignacio Munarriz]

Hi mark, maybe this trick -->>

Create a sphere (bubble) with the imagemap mapped to it but as a mixfunc 
with half transparency but double intensity (to compensate transparency)
void glow glw 0 0 4 1 1 0 -1
void mixfunc pepe 4 void glw .5 picture.cal 0 0
pepe bubble ball 0 0 4 0 0 0 1000

Create a source whith the light map
void glow pop 0 0 4 0 1 1 0
pop source pipo 0 0 4 0 0 1 180

An element to see the result
void plastic white 0 0 5 .5 .6 .8 0 0
white sphere ball 0 0 4 5 5 5 1

A view with an aft plane to discard the light map in view but not in 
calculation
rpict -va 3000 -vp 0 0 0 -vd 0 1 1 -vh 110 -vv 110

Rpict command
rpict -vf vi.vf -ab 1 pi.oct>pi.hdr

I dont know if i've miss something...

regards, ignacio

Mark Stock escribió:
> Hello,
>
> I am working on a star map for use with night renderings, and it seems 
> like it should be decomposed into two layers: one is a high-resolution 
> imagemap showing the stars themselves, the other is a low-resolution 
> "light map" that should be used to actually illuminate the scene.
>
> The problem is that I want the "light map" layer to do the 
> illumination, but I don't want it to be visible. I want the image map 
> to appear in the sky in the final rendering.
>
> I know that I can use maxrad=-1 in the image map glow source to 
> prevent it from contributing to scene illumination, and maxrad=0 to 
> allow the light map to illuminate. But mixfunc must be placed between 
> the colorpict and the glow source, forcing me to either allow both to 
> illuminate, or neither. But when the imagemap contributes to 
> illumination, the result is very noisy (obviously).
>
> This wouldn't be a problem if I could use two sky-dome sized glow 
> sources in the same scene: "skyglow source skydome 0 0 4 0 0 1 360". 
> But Radiance only sees the last one to be defined.
>
> And I can't make the light map into an "illum" because it then gets 
> treated as a point source at the zenith of my "source" description 
> (ignoring the 180-degree size of the source disc).
>
> Do I need to add transparency to the imagemap before making it into a 
> rad=-1 glow source, so that when a ray is traced between the stars, it 
> hits the illuminating light map rad=0 glow source? I am reluctant to 
> include another circa-gigabyte imagemap to the scene just for that.
>
> Am I missing something else or is this impossible?
>
> Mark
>
> PS. Shouldn't the file size limit for colorpict images be raised? I 
> get a warning for using even a 134MB picture file. I intend to go much 
> larger.
>
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