[Radiance-general] RGB irradiance from HDR-images

[Dolf Bakker]

Thanks for the response.



Andrew, your subjects are what I was looking for.

Though I am still not there yet ...  However, first I’ll try to play a
little more with it.



Lars, unfortunately that's not what I'm trying. When I made some more
progress and I am better capable to describe the problem, then I'll send
you a small update.



Thanks again!



Dolf


On Wed, Aug 7, 2013 at 10:56 AM, Lars O. Grobe <grobe at gmx.net> wrote:

> 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
>>
>
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