pcomb

radiance-general
1

Hi there
I'm working with pcomb ; I have 2 images, one with a box in a room and one with
the empty room. I just want the box so I subtract the empty room but the result
doesn't seem to look like the box in the first picture, it's much brighter in
some areas and much darker in others. Am I missing something?
Thanks for any help

Tarik

···

--
Tarik Rahman
PhD student, Institute of Perception, Action and Behaviour
School of Informatics
University of Edinburgh

2

Tarik
What I would suggest is to render the box with -av 100 100 100 -ab 0,
without light sources (should be really quick).
After that perform a multiplication of the image with the white box and the
one with the box and the room together.
Since where is black is 0, you should have just the box at the end by
filtering:

Pcomb -e 'lo=if(li(1)*li(2),li(1),0);' room whitebox > final

Or
-e 'ro=if(ri(1)*ri(2),ri(1),0); go=if(gi(1)*gi(2),gi(1),0);
bo=if(bi(1)*bi(2),bi(1),0)'

hope it works,
giulio

BTW Check that the luminance is the same at the end.

···

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Tarik
Rahman
Sent: 12 April 2005 14:26
To: Radiance general discussion
Subject: [Radiance-general] pcomb

Hi there
I'm working with pcomb ; I have 2 images, one with a box in a room and one
with
the empty room. I just want the box so I subtract the empty room but the
result
doesn't seem to look like the box in the first picture, it's much brighter
in
some areas and much darker in others. Am I missing something?
Thanks for any help

Tarik

--
Tarik Rahman
PhD student, Institute of Perception, Action and Behaviour
School of Informatics
University of Edinburgh

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3

That's a good idea, perfect. Thanks for that

Tarik
Quoting Giulio Antonutto <[email protected]>:

···

Tarik
What I would suggest is to render the box with -av 100 100 100 -ab 0,
without light sources (should be really quick).
After that perform a multiplication of the image with the white box and the
one with the box and the room together.
Since where is black is 0, you should have just the box at the end by
filtering:

Pcomb -e 'lo=if(li(1)*li(2),li(1),0);' room whitebox > final

Or
-e 'ro=if(ri(1)*ri(2),ri(1),0); go=if(gi(1)*gi(2),gi(1),0);
bo=if(bi(1)*bi(2),bi(1),0)'

hope it works,
giulio

BTW Check that the luminance is the same at the end.

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Tarik
Rahman
Sent: 12 April 2005 14:26
To: Radiance general discussion
Subject: [Radiance-general] pcomb

Hi there
I'm working with pcomb ; I have 2 images, one with a box in a room and one
with
the empty room. I just want the box so I subtract the empty room but the
result
doesn't seem to look like the box in the first picture, it's much brighter
in
some areas and much darker in others. Am I missing something?
Thanks for any help

Tarik

--
Tarik Rahman
PhD student, Institute of Perception, Action and Behaviour
School of Informatics
University of Edinburgh

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

___________________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses.

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

--
Tarik Rahman
PhD student, Institute of Perception, Action and Behaviour
School of Informatics
University of Edinburgh