[Radiance-general] Alpha channel/object matte

[Kirk Thibault]

Excellent.  I'm starting to realize that there are many different ways 
to tackle the problem and I will try your technique. Thanks!

kirk


On Nov 19, 2004, at 5:48 AM, Giulio Antonutto wrote:

> Hi,
> I am not really sure which is your question... I missed the 1st
> emails...sorry ;-)
>
> But if I am right you are trying to create an alpha channel from a 
> rendered
> picture,
>
> I would do this way:
>
> 1) generate your rendering: image
> 2) generate a mask: you can just create an image with only the object 
> and
> -av 1 1 1,
> then use "pcomb -e 'vo=if(li(1),1,0)' object > mask " to create a BW 
> image
> with 0 and 1.
>
> 3) apply the mask to the 1st image:
> pcomb -e 
> 'ro=if(li(2),ri(1),0);go=if(li(2),gi(1),0);bo=if(li(2),bi(1),0)'
> image mask > filtered
>
>
> in general all the functions are defined in rayinit.cal, into the 
> radiance
> libs...
>
> hope it helps/works,
> giulio