POV-Ray : Newsgroups : povray.general : 2-pass radiosity - alot of artifacts Server Time
31 Jul 2024 18:21:15 EDT (-0400)
  2-pass radiosity - alot of artifacts (Message 1 to 6 of 6)  
From: motorsep
Subject: 2-pass radiosity - alot of artifacts
Date: 6 Oct 2006 19:35:01
Message: <web.4526e77d1253a67d61946c600@news.povray.org>
I have been experimenting with 2-pass radiosity and I can't get my image
clean. I get alot of artifacts. Why?

Here is final image:
http://img100.imageshack.us/img100/4084/2pass01ru2.jpg

Here is 1st pass radiosity parameters (rendering resolution 64x48, no AA):
      pretrace_start 0.08
      pretrace_end   0.01
      count 400
      nearest_count 20
      error_bound 0.3
      recursion_limit 3
      low_error_factor 0.2
      gray_threshold 0
      minimum_reuse 0.015
      brightness 1.0
      adc_bailout 0.01/2

Here is 2st pass radiosity parameters (rendering resolution 640x480, with
AA):
      pretrace_start 1 // default 0.08
      pretrace_end   1 // default 0.01
      error_bound 0.8
      recursion_limit 3 // default 2
      always_sample off

And yes, I save/load radiosity file :)


Post a reply to this message

From: Tim Nikias
Subject: Re: 2-pass radiosity - alot of artifacts
Date: 6 Oct 2006 20:31:39
Message: <4526f56b$1@news.povray.org>
motorsep wrote:
> I have been experimenting with 2-pass radiosity and I can't get my image
> clean. I get alot of artifacts. Why?
> 
> Here is final image:
> http://img100.imageshack.us/img100/4084/2pass01ru2.jpg
> 
> Here is 1st pass radiosity parameters (rendering resolution 64x48, no AA):
>       pretrace_start 0.08
>       pretrace_end   0.01
>       count 400
>       nearest_count 20
>       error_bound 0.3
>       recursion_limit 3
>       low_error_factor 0.2
>       gray_threshold 0
>       minimum_reuse 0.015
>       brightness 1.0
>       adc_bailout 0.01/2
> 
> Here is 2st pass radiosity parameters (rendering resolution 640x480, with
> AA):
>       pretrace_start 1 // default 0.08
>       pretrace_end   1 // default 0.01
>       error_bound 0.8
>       recursion_limit 3 // default 2
>       always_sample off
> 
> And yes, I save/load radiosity file :)

Hm, in my experience, you using error_bound * 2 or *4. works best, and 
since you use 0.3 and 0.8, the averaging of neighbouring samples might 
not be optimal. Additionally, I'm not sure if you need that high a 
recursion limit for this scene, I guess 2 should suffice (unless the 
windows are real objects, but if you're using two-pass, I'd suggest 
leaving them out of the initial pass entirely).
Have you taken a look at my experiments with two-pass renderings?

http://www.nolights.de/projects/radiosity/radiosity.html

I try to explain a few things there which might give you additional 
hints, although the only three things I'd suggest are recursion_limit of 
2, proper error_bound multiplying, and setting count higher.

Regards,
Tim

-- 
aka "Tim Nikias"
Homepage: <http://www.nolights.de>


Post a reply to this message

From: Alain
Subject: Re: 2-pass radiosity - alot of artifacts
Date: 7 Oct 2006 11:47:50
Message: <4527cc26$1@news.povray.org>
motorsep nous apporta ses lumieres en ce 06/10/2006 19:32:
> I have been experimenting with 2-pass radiosity and I can't get my image
> clean. I get alot of artifacts. Why?
> 
> Here is final image:
> http://img100.imageshack.us/img100/4084/2pass01ru2.jpg
> 
> Here is 1st pass radiosity parameters (rendering resolution 64x48, no AA):
>       pretrace_start 0.08
>       pretrace_end   0.01
>       count 400
>       nearest_count 20
>       error_bound 0.3
>       recursion_limit 3
>       low_error_factor 0.2
>       gray_threshold 0
>       minimum_reuse 0.015
>       brightness 1.0
>       adc_bailout 0.01/2
> 
> Here is 2st pass radiosity parameters (rendering resolution 640x480, with
> AA):
>       pretrace_start 1 // default 0.08
>       pretrace_end   1 // default 0.01
>       error_bound 0.8
>       recursion_limit 3 // default 2
>       always_sample off
> 
> And yes, I save/load radiosity file :)
> 
> 
> 
I'm not sure about it, but maybe, just maybe, using a larger resolution for the 
first pass could help. It may gather more radiosity samples.
A low error_bound need higher count, you may need around 1000 or more, possibly 
all the way up to 1600. I regularly use count in the 300~500 range with default 
error_bound.

-- 
Alain
-------------------------------------------------
Beam me up Scotty. This isn't the men's room.


Post a reply to this message

From: motorsep
Subject: Re: 2-pass radiosity - alot of artifacts
Date: 9 Oct 2006 14:50:00
Message: <web.452a991a35dc67f5213a267d0@news.povray.org>
I am so frustrated :(
I have tried everything and I still get terrible image with artifacts. I
don't know why :( Maybe it has to do with geometry in my scene or scale.. I
don't know.
I would appreciate if somebody could take my scene and look into it and tell
what do I do wrong, please.

http://rapidshare.de/files/36122463/interior.rar.html

Thank you!


Post a reply to this message

From: Alain
Subject: Re: 2-pass radiosity - alot of artifacts
Date: 11 Oct 2006 05:55:43
Message: <452cbf9f$1@news.povray.org>
motorsep nous apporta ses lumieres en ce 09/10/2006 14:46:
> I am so frustrated :(
> I have tried everything and I still get terrible image with artifacts. I
> don't know why :( Maybe it has to do with geometry in my scene or scale.. I
> don't know.
> I would appreciate if somebody could take my scene and look into it and tell
> what do I do wrong, please.

> http://rapidshare.de/files/36122463/interior.rar.html

> Thank you!


Rendering now. Aparently, your error_bound is to low. Testing with error_bound 
0.5 instead of 0.05 and the artefacts on the ceiling are almost gone.
I propose using error_bound of about 0.7 to 1.0. You may even try using the 
default value: 1.8.

-- 
Alain
-------------------------------------------------
If one synchronized swimmer drowns, do the rest have to drown too?


Post a reply to this message

From: Verm
Subject: Re: 2-pass radiosity - alot of artifacts
Date: 11 Oct 2006 06:49:04
Message: <452ccc20$1@news.povray.org>
motorsep wrote:
> I am so frustrated :(
That's what you get for using radiosity.
> I have tried everything and I still get terrible image with artifacts. I
> don't know why :( Maybe it has to do with geometry in my scene or scale.. I
> don't know.
> I would appreciate if somebody could take my scene and look into it and tell
> what do I do wrong, please.

If you rendered the room at night, with a light inside the room it would 
be far easier. It's a cheat but you'd get a nice image with just the 
default pov radiosity settings and an indoor light.

At the moment (apart from a very small patch of floor) your scene is 
only lit by radiosity.

Remember that increasing the error_bound makes it smoother, so if it 
looks blotchy increase the error bound.

Is this render ok?
(apart from the exposure as I've not got megapov)
http://www.thirteen.dynu.com/~martin/pov/test_pass1.jpg

All I did was render the first pass at 160*120 and then increase your 
2nd stage error bound to 0.8

The other issue with your lighting is the room seems to be floating in 
mid air, if you added a ground plane then you'd have less light hitting 
your ceiling from outside.


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.