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26 Sep 2022 06:01:41 EDT (-0400)
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From: Warren
Subject: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 13 Jan 2022 09:10:00
Message: <web.61e031d584692a571d602a3e756b296@news.povray.org>
Hi,
I post a message here, because I get a weird render with povray 3.8.0 beta 1 of
a scene with the following resolution : 1280x960 (see attached image with this
message) , you can see a white stain that has the shape of a heart near the
pentagram. When I render this same scene with stable v3.7.0 the white stain
doesn't appear. And even weird, when I render this scene with povray "3.8.0
beta1" but with the resolution of 640x480, I don't get this white stain in the
final image. Usually I'm cautious before I claim this is a bug and that the
error is not between the keyboard and the chair, but there is something wrong
there.
Regards,
Antoine.


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Attachments:
Download 'halloweenhousenighttime3.8.png' (1167 KB)

Preview of image 'halloweenhousenighttime3.8.png'
halloweenhousenighttime3.8.png


 

From: Alain Martel
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 13 Jan 2022 11:14:26
Message: <61e04fe2$1@news.povray.org>
Le 2022-01-13 à 09:06, Warren a écrit :
> Hi,
> I post a message here, because I get a weird render with povray 3.8.0 beta 1 of
> a scene with the following resolution : 1280x960 (see attached image with this
> message) , you can see a white stain that has the shape of a heart near the
> pentagram. When I render this same scene with stable v3.7.0 the white stain
> doesn't appear. And even weird, when I render this scene with povray "3.8.0
> beta1" but with the resolution of 640x480, I don't get this white stain in the
> final image. Usually I'm cautious before I claim this is a bug and that the
> error is not between the keyboard and the chair, but there is something wrong
> there.
> Regards,
> Antoine.

Yes, there is something wrong. Now, a few questions :
Is there a resolution where it just start to show up ?
Did you try at 800x600, 1024x768, 1600x1200 ?
Did you try at some different aspect ratio, like 800x800 or 1600x800 ?

You should post the scene file to povray.binaries.scene-files
Be sure to include any custom .inc files and image used. If there are 
more than a single file used, zip them together.
That way, we can try to reproduce your issue.


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From: Cousin Ricky
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 13 Jan 2022 20:37:05
Message: <61e0d3c1@news.povray.org>
On 2022-01-13 10:06 (-4), Warren wrote:
> Hi,
> I post a message here, because I get a weird render with povray 3.8.0 beta 1 of
> a scene with the following resolution : 1280x960 (see attached image with this
> message) , you can see a white stain that has the shape of a heart near the
> pentagram. When I render this same scene with stable v3.7.0 the white stain
> doesn't appear. And even weird, when I render this scene with povray "3.8.0
> beta1" but with the resolution of 640x480, I don't get this white stain in the
> final image.

What I've found so far:
 - The artifact varies with the image size.  A 960x720 render leaves an
   oblong stain on the upper left vertex.
 - The artifact isn't completely absent with 640x480.  At 640x480, tiny
   white spots appear along the veins of the pentagram, but they are
   absent in a 3.7 render.  I presume that this means you did not put
   them there deliberately, and that they are related to the big heart-
   shaped stain.
 - 3.8 beta 2 does not solve the problem.


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From: Warren
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 14 Jan 2022 06:10:00
Message: <web.61e1592fc82cc78e1d602a3e756b296@news.povray.org>
Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2022-01-13 10:06 (-4), Warren wrote:
> > Hi,
> > I post a message here, because I get a weird render with povray 3.8.0 beta 1 of
> > a scene with the following resolution : 1280x960 (see attached image with this
> > message) , you can see a white stain that has the shape of a heart near the
> > pentagram. When I render this same scene with stable v3.7.0 the white stain
> > doesn't appear. And even weird, when I render this scene with povray "3.8.0
> > beta1" but with the resolution of 640x480, I don't get this white stain in the
> > final image.
>
> What I've found so far:
>  - The artifact varies with the image size.  A 960x720 render leaves an
>    oblong stain on the upper left vertex.
>  - The artifact isn't completely absent with 640x480.  At 640x480, tiny
>    white spots appear along the veins of the pentagram, but they are
>    absent in a 3.7 render.  I presume that this means you did not put
>    them there deliberately, and that they are related to the big heart-
>    shaped stain.
>  - 3.8 beta 2 does not solve the problem.

There are other things to consider:
- First off, set the boolean 'PlaceWell' (line 19 of main pov file) to false, to
get a faster rendering, the heart shape artifact being always there.
- Changing the minimum_reuse value from '0.015' to '0.01' make the 'heart shaped
artifact' to disappear, but the little white stains you talked about are there,
it seems.


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From: William F Pokorny
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 16 Jan 2022 13:46:53
Message: <61e4681d@news.povray.org>
On 1/14/22 6:06 AM, Warren wrote:
> Cousin Ricky <ric### [at] yahoocom> wrote:
>> On 2022-01-13 10:06 (-4), Warren wrote:
>>> Hi,
>>> I post a message here, because I get a weird render with povray 3.8.0 beta 1 of
>>> a scene with the following resolution : 1280x960 (see attached image with this
>>> message) , you can see a white stain that has the shape of a heart near the
>>> pentagram. When I render this same scene with stable v3.7.0 the white stain
>>> doesn't appear. And even weird, when I render this scene with povray "3.8.0
>>> beta1" but with the resolution of 640x480, I don't get this white stain in the
>>> final image.
>>
>> What I've found so far:
>>   - The artifact varies with the image size.  A 960x720 render leaves an
>>     oblong stain on the upper left vertex.
>>   - The artifact isn't completely absent with 640x480.  At 640x480, tiny
>>     white spots appear along the veins of the pentagram, but they are
>>     absent in a 3.7 render.  I presume that this means you did not put
>>     them there deliberately, and that they are related to the big heart-
>>     shaped stain.
>>   - 3.8 beta 2 does not solve the problem.
> 
> There are other things to consider:
> - First off, set the boolean 'PlaceWell' (line 19 of main pov file) to false, to
> get a faster rendering, the heart shape artifact being always there.
> - Changing the minimum_reuse value from '0.015' to '0.01' make the 'heart shaped
> artifact' to disappear, but the little white stains you talked about are there,
> it seems.
> 

The following might, or might not, be of help to you with official 
versions of POV-Ray.

I took a quick look at at this bug with my current povr branch and found 
along with some recent bounding code changes it got me to a more stable 
fail for a bug I've been chasing for years. Details posted in the v4.0 
group.

My povr branch is now considerably different than official POV-Ray 
offerings, but after translating the pentagram up by 2x the thread 
radius(a) I got away from the 'white regions.' I never saw the heart 
shaped one - no idea why not in povr. Image attached.

(a) - Media needs clean start and stop intervals. Near coincident 
shape/surfaces can cause confusion and leave intervals open - and with 
emission media this results in extremely bright regions.

Where you had media I moved from min, max samples and interval 
specifications to just 'samples 10'.

In many places you are using the srgb keyword with channel values 
outside the 0-1 range. My povr branch doesn't allow this because any 
'srgb calculation' outside the 0-1 range is wacky. See post elsewhere 
for details. If you need values outside 0-1, use rgb to exactly specify 
what you want for internal linear values.

includes/outdoorsLamp.inc -> debug statement line 218 uses LampZpos and 
it should be LampZPos.

Bill P.


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Attachments:
Download 'image_povrtracefix.jpg' (105 KB)

Preview of image 'image_povrtracefix.jpg'
image_povrtracefix.jpg


 

From: Cousin Ricky
Subject: Re: weird white stain with beta povray v3.8.0 (not with povrayv3.7.0)
Date: 16 Jan 2022 23:46:33
Message: <61e4f4a9$1@news.povray.org>
On 2022-01-16 14:46 (-4), William F Pokorny wrote:
> 
> In many places you are using the srgb keyword with channel values
> outside the 0-1 range. My povr branch doesn't allow this because any
> 'srgb calculation' outside the 0-1 range is wacky. See post elsewhere
> for details. If you need values outside 0-1, use rgb to exactly specify
> what you want for internal linear values.

For what it's worth, these are the out-of-domain sRGB calls, evaluated
under assumed_gamma 1:

customTextures.inc:
  srgb < 1, 0.9, 0.65> * 1.3 = rgb <1.8233, 1.4313, 0.6829>
  srgb < 1, 0.9, 0.65> * 1.15 = rgb <1.3758, 1.0815, 0.5186>
pentagramObject.inc:
  srgb 8 = rgb <131.4473, 131.4473, 131.4473>
  srgb 3 = rgb <12.8298, 12.8298, 12.8298>
pumpkin.inc:
  srgb < 1.5, 1, 0> = rgb <2.5372, 1.0000, 0.0000>

The post elsewhere with details:
https://news.povray.org/povray.general/thread/%3Cweb.60649d9bb9b7dccdd98418916e066e29%40news.povray.org%3E/


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From: Kenneth
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 17 Jan 2022 21:50:00
Message: <web.61e62a6cc82cc78e4cef624e6e066e29@news.povray.org>
[Running v3.8.0 beta 1 in Windows 10]

This is a very tricky problem to diagnose; I am seeing inconsistent results from
render to render, even at the problematic 1280X960 render size. Sometimes the
heart-shaped stain is there, sometimes not.

[Warren wrote:]
// There are other things to consider:
// First off, set the boolean 'PlaceWell' (line 19 of main pov file) to false,
// to get a faster rendering, the heart shape artifact being always there.

Even with that change, I still get inconsistent results.

Interestingly, I commented-out this code block in your main file to see what
would happen; it's your lamp-placement block, I think...

#for( It, 0, PositionsNum - 1, 1 )
 ...
 #end
#end

..... but I still see the (inconsistent) artifact.

That still leaves your pumpkins and candles in the scene-- with *their* lights.
Maybe those include files would be a place to look? Perhaps you could try
plugging in some crazy values in certain places, to try and *force* the artifact
to always show up and to look even worse.

Strange as it seems, if I simply eliminate your  +bs8  on the command line, I
never see the artifact at 1280X960...well, not in 15 render attempts, anyway. I
have no idea why that would matter.


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From: Kenneth
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 18 Jan 2022 01:00:00
Message: <web.61e65633c82cc78e4cef624e6e066e29@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:
>
> Strange as it seems, if I simply eliminate your  +bs8  on the command line, I
> never see the artifact at 1280X960...well, not in 15 render attempts,
> anyway. I have no idea why that would matter.

Forget that; it's probably of no real consequence...because I think I've solved
at least part of the problem (the large heart-shaped artifact).
>
> ...I am seeing inconsistent results from
> render to render, even at the problematic 1280X960 render size. Sometimes the
> heart-shaped stain is there, sometimes not.
>

That's because of the scene's radiosity settings. I noticed that there was no
maximum_reuse value given, which means that it defaults to 0.2-- which is quite
large and can result in large splotchy artifacts-- the heart shape, for example.

My image examples are from an animation test. I changed minimum_reuse to 0.09...
and I now see LOTS of such artifacts. The reason why my earlier tests seemed
inconsistent is because of the random nature of such 'splotches' from render to
render, given the values used; and it just happened that the scene's rad
settings were sometimes producing only ONE *major* artifact...or none. The sizes
of such splotches vary according to the 'spread' between the minimum_reuse and
maximum_reuse values.

I also did a test with these rad values:
minimum_reuse 0.03
maximum_reuse 0.031

This produces even more splotches, all of the same (smaller) size.

It's obvious that these super-bright artifacts are showing up along the 'lines'
of the pentagram. The remainder of the problem must be that some of its srgb
colors are 'greater than 1.0' as was mentioned earlier, and are interacting
weirdly with radiosity; or that the scene's lights and fade_powers are somehow
too bright.

Apparently, radiosity is picking up a super-bright color from *somewhere*, and
using it in its calculations.


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Attachments:
Download 'halloweenhouse_artifacts_kw.jpg' (246 KB)

Preview of image 'halloweenhouse_artifacts_kw.jpg'
halloweenhouse_artifacts_kw.jpg


 

From: Kenneth
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 18 Jan 2022 04:50:00
Message: <web.61e68ca3c82cc78e4cef624e6e066e29@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:

>
> That's because of the scene's radiosity settings...
> My image examples are from an animation test. I changed minimum_reuse to 0.09...
> and I now see LOTS of such artifacts...

Forgot to mention that I changed the scene's rad 'count' from 800 to 80 for
these test renders, just to make quicker tests.


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From: Bald Eagle
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 18 Jan 2022 07:00:00
Message: <web.61e6aba3c82cc78e1f9dae3025979125@news.povray.org>
Good detective work!  :)

Are they "hearts" or --- nephroids?

Is there some sort of "reflection" effect, esp with the circle, that would give
rise to this?

Can the symbol be raised / lowered, scaled, lines widened/narrowed to show an
effect on the artifacts?

Does the same artifact show up with a square or an ellipse...?


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