[Radiance-general] RGB irradiance from HDR-images

[Lars O. Grobe]

Hi Dolf,

is it that you want to trace rays for image pixels dependent on their 
pixel value? So something like "if (pixel_red >=.5) then rtrace 
pixel_origin pixel_direction"? For that, you can use rcalc, which 
understands float triples (aka pixels values) as input, and can output 
either valid origin/direction vectors or nul-vectors depending on the input.

Cheers, Lars.

Cheers, Lars.
> Hello everybody,
>
>
> is it possible to calculate the RGB irradiance values from a HDR-image 
> (generated by Rpict)?
> So I'm trying to use the "photographic film/sensor" of  the "camera" 
> as a photosensor.
>
> I am trying to do use a HDR image, since I want to apply various masks 
> on the HDR image.
> So I am trying to cut out various sections of my photographic film, 
> and placing a photosensor / lux-meter on the cut-out sections of the 
> photographic film.
>
> I was hoping to use something like this:
>
> rmagic basic.hdr | rtrace \-i+ \-dv \-h\- \-ab 3 scene.oct > output1a
> rmagic basic.hdr | rtrace \-i+ \-dv \-h\- \-ab 3 scene.oct | rcalc -e 
> '$1=(0.67*$1+0.265*$2+0.065*$3)*179'  > output1b
> rmagic mask1.hdr | rtrace \-i+ \-dv \-h\- \-ab 3 scene.oct > output2a
> rmagic mask1.hdr | rtrace \-i+ \-dv \-h\- \-ab 3 scene.oct | rcalc -e 
> '$1=(0.67*$1+0.265*$2+0.065*$3)*179' > output2b
> rmagic mask2.hdr | rtrace \-i+ \-dv \-h\- \-ab 3 scene.oct > output3a
> rmagic mask2.hdr | rtrace \-i+ \-dv \-h\- \-ab 3 scene.oct | rcalc -e 
> '$1=(0.67*$1+0.265*$2+0.065*$3)*179' > output3b
>
> Tip, tricks and suggestions are very welcome!
>
> Thanks in advance,
>
>
> Dolf Bakker