POV-Ray : Newsgroups : povray.binaries.images : Ooops. Odd blotches. Server Time
31 Jul 2024 20:13:23 EDT (-0400)
  Ooops. Odd blotches. (Message 1 to 8 of 8)  
From: [GDS|Entropy]
Subject: Ooops. Odd blotches.
Date: 13 Mar 2009 03:13:21
Message: <49ba0791@news.povray.org>
1) I messed up scaling the water iso, so the waves are too wide to see.
2) I used a crappy HDR probe image.
3) I used the vine macro and the corrosion macro, just to see if they play 
nice. They do.

This image uses radiosity, but I doubt it caused the odd blotches.

Anyone have any ideas about what these are? Once I can figure it out, I'll 
rerender...as it took 13hr..

ian


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From: Bill Pragnell
Subject: Re: Ooops. Odd blotches.
Date: 13 Mar 2009 05:15:00
Message: <web.49ba240d644b8e0a6dd25f0b0@news.povray.org>
"[GDS|Entropy]" <gds### [at] hotmailcom> wrote:
> This image uses radiosity, but I doubt it caused the odd blotches.
>
> Anyone have any ideas about what these are? Once I can figure it out, I'll
> rerender...as it took 13hr..

They look like radiosity artifacts to me. Try raising the count. Also, make sure
recursion_limit is high enough that radiosity rays are making it through the
water surface!

Bill


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From: [GDS|Entropy]
Subject: Re: Ooops. Odd blotches.
Date: 13 Mar 2009 08:19:42
Message: <49ba4f5e$1@news.povray.org>
"Bill Pragnell" <bil### [at] hotmailcom> wrote in message 
news:web.49ba240d644b8e0a6dd25f0b0@news.povray.org...
> "[GDS|Entropy]" <gds### [at] hotmailcom> wrote:
>> This image uses radiosity, but I doubt it caused the odd blotches.
>>
>> Anyone have any ideas about what these are? Once I can figure it out, 
>> I'll
>> rerender...as it took 13hr..
>
> They look like radiosity artifacts to me. Try raising the count. Also, 
> make sure
> recursion_limit is high enough that radiosity rays are making it through 
> the
> water surface!
>
> Bill

Turns out that it was MTL... O_o'

I fixed my isosurface. And I found a bug in my macros.
Apparently, something does not like it when your trace test vector is 
different between calls to the various macros. WTF? I thought that I had 
written them so that it didn't matter. Guess I was wrong.

Once this next render is done I will post its source, as I am not seeing the 
problem.

My next version will probably include the glacier iso and snow macros, so I 
can have spring on the lower left and winter on the upper right, just to get 
some thematic asymmetric balance in there.

ian


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From: Trevor G Quayle
Subject: Re: Ooops. Odd blotches.
Date: 13 Mar 2009 13:05:01
Message: <web.49ba9221644b8e0a81c811d20@news.povray.org>
"[GDS|Entropy]" <gds### [at] hotmailcom> wrote:
> 1) I messed up scaling the water iso, so the waves are too wide to see.
> 2) I used a crappy HDR probe image.
> 3) I used the vine macro and the corrosion macro, just to see if they play
> nice. They do.
>
> This image uses radiosity, but I doubt it caused the odd blotches.
>
> Anyone have any ideas about what these are? Once I can figure it out, I'll
> rerender...as it took 13hr..
>
> ian

It looks like they may possibly be bird droppings.

Actually they do look like radiosity artifacts.

-tgq


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From: clipka
Subject: Re: Ooops. Odd blotches.
Date: 14 Mar 2009 12:35:00
Message: <web.49bbdbc3644b8e0a4c2c4c080@news.povray.org>
"[GDS|Entropy]" <gds### [at] hotmailcom> wrote:

Looks weird (even without the blotches). Like it!

> This image uses radiosity, but I doubt it caused the odd blotches.

I *guarantee* you it did, beyond any doubt.

The blotches also tell me that you're using a version of POV prior to
3.7.0.beta.29-rad1 (or a derivative; given that you mention HDR, I reckon it's
MegaPOV 1.2.1)

Your scene's setting is the role model for the infamous POV 3.6 (and earlier)
"black splotchy artifacts" radiosity bug: An abundance of reflective stuff with
an abundance of interreflection. With this setting, you're almost *inevitably*
to contract the "black pox".

There's just one thing to rule them all, find them, bring them all, and in the
brightness bind them: Crank up max_trace_level a really good deal. All other
resistance is futile.

(Or use the current POV 3.7 beta of course.)


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From: clipka
Subject: Re: Ooops. Odd blotches.
Date: 14 Mar 2009 12:50:01
Message: <web.49bbdfbd644b8e0a4c2c4c080@news.povray.org>
"Bill Pragnell" <bil### [at] hotmailcom> wrote:
> They look like radiosity artifacts to me. Try raising the count. Also, make sure
> recursion_limit is high enough that radiosity rays are making it through the
> water surface!

recursion_limit is not the screw to tweak here. That parameter is somewhat akin
to the max_trace_level, but rather than limiting the number of *total* bounces
calculated, it just limits the number of *diffuse* bounces. There may be an
arbitrary number of reflection/refraction bounces in between - radiosity
doesn't care (unless the general max_trace_level restriction kicks in).

I never tested it, but thinking about it, my first guess would be that raising
recursion_limit would actually make the splotches worse in number (albeit
possibly weaker).


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From: Paolo Gibellini
Subject: Re: Ooops. Odd blotches.
Date: 18 Mar 2009 09:07:03
Message: <49c0f1f7$1@news.povray.org>
Mmm...
Apart of artifacts, with some texture correction you could realize a 
spherical pizza!
;-)
Paolo

 >[GDS|Entropy]  on date 13/03/2009 08:13 wrote:
> 1) I messed up scaling the water iso, so the waves are too wide to see.
> 2) I used a crappy HDR probe image.
> 3) I used the vine macro and the corrosion macro, just to see if they play 
> nice. They do.
> 
> This image uses radiosity, but I doubt it caused the odd blotches.
> 
> Anyone have any ideas about what these are? Once I can figure it out, I'll 
> rerender...as it took 13hr..
> 
> ian 
> 
>


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From: Carlo C 
Subject: Re: Ooops. Odd blotches.
Date: 18 Mar 2009 12:05:01
Message: <web.49c11b5f644b8e0a961ca5200@news.povray.org>
Paolo Gibellini <p.g### [at] gmailcom> wrote:
> Mmm...
> Apart of artifacts, with some texture correction you could realize a
> spherical pizza!
> ;-)
> Paolo

Ahhh!
*Per fortuna che ero seduto!*
A four-cheese pizza with tomato? :-D
(sorry for off-topic)

--
Carlo


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