[Radiance-general] remove light probe image from background

[Katja Doerschner]

Hi Rob,
Thank you for your suggestion.
I tried something like that before, and encountered an interesting  
artifact (well maybe not so interesting).
I have a perfectly specular object illuminated by a light probe. In a  
second image I used the same shape but made the object glow  
(material) and the environment black - This created something like a  
mask. Then I wrote a small program which picks all the non-black  
pixels in the mask and replaces them with the content from the first  
(specular) image.
To my surprise these shapes never matched up perfectly, the mask  
created with the non-specular material was always a few pixels bigger  
than the specular shape, as a result there were always a few  
background pixels selected. I tried other materials in combination  
with different lights(ambient etc) - always encountering the same  
problem.

katja

On Apr 19, 2007, at 2:58 PM, Fitzsimmons, Rob wrote:

> I've done it by creating a duplicate scene (your rif file) and  
> subsititute a overcast gensky (just something that will make the  
> sky white, change all your materials to black with no specular.  
> Then render with -ab 0 - to get a black and white "mask" Render  
> will not take long with no bounces.
> I've then converted the mask pic to a standard ldr tiff - use it in  
> photoshop as a masking layer.
> You could also do it with the original hdrs through pcomb - you'd  
> have to check the manual on that.
>
> Rob F
>
> From: Katja Doerschner [mailto:doers003 at umn.edu]
> Sent: Thursday, April 19, 2007 12:43 PM
> To: radiance-general at radiance-online.org
> Subject: [Radiance-general] remove light probe image from background
>
> Hello,
>
> (I apologize if this email went out twice ... I forgot to update my  
> subscription to my current email...)
>
>
> I am illuminating a scene with a light probe.
> In the resulting rendered image I do not want to have the probe  
> image in the background.
>
> Does anyone know if there is a setting in Radiance that would make  
> this possible?
>
> Thanks for your help!
>
> Kind Regards,
>
> katja
>
> Katja Doerschner
> University of Minnesota
> Psychology Department
> 218 Elliott Hall
> 75 East River Road
> Minneapolis, MN 55455-0344
> Phone:+1 612 626-8551
>
>
>
> _______________________________________________
> Radiance-general mailing list
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Katja Doerschner
University of Minnesota
Psychology Department
218 Elliott Hall
75 East River Road
Minneapolis, MN 55455-0344
Phone:+1 612 626-8551
http://vision.psych.umn.edu/~doerschner


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