Hi
Does anyone know why inserting a diffuse object in an IBL scene, such as the
red_plastic sphere in the Debevec tutorial does not reflect light properly,
i.e. renders as black? It works sometimes and other times it doesn't, I don't
understand why. The metal spheres such as the gold and steel ones and the
crystal sphere all render perfectly but sometimes (not all the time) any
object with plastic material doesn't render properly.
Tarik
···
--
Tarik Rahman
PhD student, Institute of Perception, Action and Behaviour
School of Informatics
University of Edinburgh
I had this occur as well when previewing in rview (rvu) but everything rendered fine when a final render was made.
To answer your question, I don;t know why. I run RADIANCE on a Mac, OSX 10.3.X.
kirk
···
On Mar 2, 2005, at 5:13 AM, Tarik Rahman wrote:
Hi
Does anyone know why inserting a diffuse object in an IBL scene, such as the
red_plastic sphere in the Debevec tutorial does not reflect light properly,
i.e. renders as black? It works sometimes and other times it doesn't, I don't
understand why. The metal spheres such as the gold and steel ones and the
crystal sphere all render perfectly but sometimes (not all the time) any
object with plastic material doesn't render properly.
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
A possible reason:
is it -ab > 0 (i.e. rvu -ab 1 or rpict -ab 1) ?
(needed if there are only secondary sources of light, such as the Sky...)
hope it helps,
giulio
PS I have Radiance 3.6.1 on 10.3.8, MacOSX, everything ok here, BTW it's a
pleasure to see how many people are running Radiance on a Mac ;-))
···
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Kirk
Thibault
Sent: 02 March 2005 14:09
To: Radiance general discussion
Subject: Re: [Radiance-general] Objects with plastic material in IBL scene
I had this occur as well when previewing in rview (rvu) but everything
rendered fine when a final render was made.
To answer your question, I don;t know why. I run RADIANCE on a Mac,
OSX 10.3.X.
kirk
On Mar 2, 2005, at 5:13 AM, Tarik Rahman wrote:
Hi
Does anyone know why inserting a diffuse object in an IBL scene, such
as the
red_plastic sphere in the Debevec tutorial does not reflect light
properly,
i.e. renders as black? It works sometimes and other times it doesn't,
I don't
understand why. The metal spheres such as the gold and steel ones and
the
crystal sphere all render perfectly but sometimes (not all the time)
any
object with plastic material doesn't render properly.
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
_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
___________________________________________________________________
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Giulio is correct. IBL creates glow sources rather than lights, so materials with primarily diffuse components rely on the ambient calculation to pick up any illumination at all, and the parameters must be set such that Radiance can find the bright areas in the light probe. Something like -ab 1 -ad 1024 -as 512 at least, and sometimes even that is not enough. There are tools for locating and replacing bright areas in the light probe with equivalent sources. I think HDRshop has such a tool, and others have worked on similar tools. There are even a number of papers on it -- I know Alex Keller wrote one, and Bernhard Spanglang worked on this as part of his thesis, and you can check out his talk from the first Radiance workshop online:
http://www.radiance-online.org/radiance-workshop1/cd/Spanlang/index.html
See also Santiago Torres' presentation from the second workshop:
http://www.radiance-online.org/radiance-workshop2/cd/Torres/abstract.html
This topic is also well-covered in the notes Paul Debevec has online at his website from the various Siggraph tutorials he's given. See for example page 8 from "Paul Debevec's main slides on HDRI and Image-Based Lighting (6.7MB pdf)" in the notes of the Siggraph 2003 course on IBL:
http://www.debevec.org/IBL2003/
There are resources out there. It's a matter of finding them, as always...
-Greg
···
From: Giulio Antonutto <[email protected]>
Date: March 2, 2005 6:54:23 AM PST
A possible reason:
is it -ab > 0 (i.e. rvu -ab 1 or rpict -ab 1) ?
(needed if there are only secondary sources of light, such as the Sky...)
hope it helps,
giulio
PS I have Radiance 3.6.1 on 10.3.8, MacOSX, everything ok here, BTW it's a
pleasure to see how many people are running Radiance on a Mac ;-))
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Kirk
Thibault
I had this occur as well when previewing in rview (rvu) but everything
rendered fine when a final render was made.
To answer your question, I don;t know why. I run RADIANCE on a Mac,
OSX 10.3.X.
kirk
On Mar 2, 2005, at 5:13 AM, Tarik Rahman wrote:
Hi
Does anyone know why inserting a diffuse object in an IBL scene, such
as the
red_plastic sphere in the Debevec tutorial does not reflect light
properly,
i.e. renders as black? It works sometimes and other times it doesn't,
I don't
understand why. The metal spheres such as the gold and steel ones and
the
crystal sphere all render perfectly but sometimes (not all the time)
any
object with plastic material doesn't render properly.
Tarik
Duh, that's how I remedied the situation too. Man, I am losing my mind.
thanks for the reality check.
kirk
···
On Mar 2, 2005, at 9:54 AM, Giulio Antonutto wrote:
A possible reason:
is it -ab > 0 (i.e. rvu -ab 1 or rpict -ab 1) ?
(needed if there are only secondary sources of light, such as the Sky...)
hope it helps,
giulio