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From: olafcbx
Subject: Quality difference btw V3.1 and V3.6
Date: 26 Dec 2005 12:05:02
Message: <web.43b022181d99fdc46c6c46740@news.povray.org>
Hi,

I retraced a scene I did previous with with V3.1 with V3.6 (for Windows).
I rendered a lot faster, but I am not happy with the quality.
The Anti aliassing looks worce, and I noticed strange black lines on edgeds
that I havent seen before.

As the images are 7800 x 5200 pixels I do not include them :-)

This is the .ini file I used for both V3.1 and V3.6

I re-rendered the same scene with 3.1 and 3.6 again to be sure and used
Paint Shop pro to compare side-by-side.

Is there a known problem or a fix?
Or can I no longer expect the same results without a modification in the
..ini file?

Thanks,

Olaf

------------- the ini file used ----------------

; O. Veenstra  2003/06/29
; cbx total for zazzle
;------------------------
Input_file_name     = raytracezazzlecbxscenescbx_zazzle_01.pov
Output_File_Type    = N
output_file_name    = raytracetile_colorfull_7800_5200_v31

Library_Path        = raytracezazzlecbxscenes

Width               = 7800
Height              = 5200

Quality             = 9


; anti alias options
; ------------------

antialias               =    On
antialias_Threshold     =    0.5

Sampling_Method         =    2
Jitter                  =    Off

display = no


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From: olafcbx
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 26 Dec 2005 13:20:00
Message: <web.43b032d33a163c4c6c6c46740@news.povray.org>
"olafcbx" <ola### [at] wxsnl> wrote:
> Hi,
>
> I retraced a scene I did previous with with V3.1 with V3.6 (for Windows).
> I rendered a lot faster, but I am not happy with the quality.
> The Anti aliassing looks worce, and I noticed strange black lines on edgeds
> that I havent seen before.
>
> As the images are 7800 x 5200 pixels I do not include them :-)
>
> This is the .ini file I used for both V3.1 and V3.6
>
> I re-rendered the same scene with 3.1 and 3.6 again to be sure and used
> Paint Shop pro to compare side-by-side.
>
> Is there a known problem or a fix?
> Or can I no longer expect the same results without a modification in the
> ..ini file?
>
> Thanks,
>
> Olaf
>
> ------------- the ini file used ----------------
>
> ; O. Veenstra  2003/06/29
> ; cbx total for zazzle
> ;------------------------
> Input_file_name     = raytracezazzlecbxscenescbx_zazzle_01.pov
> Output_File_Type    = N
> output_file_name    = raytracetile_colorfull_7800_5200_v31
>
> Library_Path        = raytracezazzlecbxscenes
>
> Width               = 7800
> Height              = 5200
>
> Quality             = 9
>
>
> ; anti alias options
> ; ------------------
>
> antialias               =    On
> antialias_Threshold     =    0.5
>
> Sampling_Method         =    2
> Jitter                  =    Off
>
> display = no

Hi,

Me again!

I put some images on my homepage so you can see the difference:

http://home.wxs.nl/~olafveen/povray/povray.html

Hope this will help....


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From: Tim Nikias
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 26 Dec 2005 13:37:32
Message: <43b0386c@news.povray.org>
As for the tile on the floor, I guess it's a superellipsoid. I'm not sure
why, but perhaps something has changed in the way the code is calculated,
but maybe "sturm" might help.

As for the aliasing: POV-Ray 3.6 doesn't clip the colors before averaging
the pixels anymore. So at edges where a very bright and a very dark color
meet (e.g. rgb 3 vs rgb .01) you get a very bright pixel. POV-Ray 3.1
clipped before the averaging, and you always had color samples in the range
rgb 0 to rgb 1. If you want the same effect, either render in 3.1, or render
the scene at several times the size and reduce it with a paint programm to
average neighbouring pixels.

I myself am not as happy with the new handling either, and hope that in
future version you might choose which behaviour you want (the new handling
is more realistic, but, as you noticed, sometimes defeats the purpose of
antialiasing that we want/need).

But, in general, it is often wise to have copies of old applications around
to run old files on them. There's always something that changes, and
sometimes the new behaviour isn't compatible with the new version at all.
(Though that often covers other apps than POV-Ray, they do a fairly good job
at backward-compability).

Regards,
Tim

-- 
aka "Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: Alain
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 26 Dec 2005 13:43:49
Message: <43b039e5$1@news.povray.org>
olafcbx nous apporta ses lumieres en ce 2005-12-26 12:02:
> Hi,
> 
> I retraced a scene I did previous with with V3.1 with V3.6 (for Windows).
> I rendered a lot faster, but I am not happy with the quality.
> The Anti aliassing looks worce, and I noticed strange black lines on edgeds
> that I havent seen before.
> 
> As the images are 7800 x 5200 pixels I do not include them :-)
> 
> This is the .ini file I used for both V3.1 and V3.6
> 
> I re-rendered the same scene with 3.1 and 3.6 again to be sure and used
> Paint Shop pro to compare side-by-side.
> 
> Is there a known problem or a fix?
> Or can I no longer expect the same results without a modification in the
> ..ini file?
> 
> Thanks,
> 
> Olaf
> 
> ------------- the ini file used ----------------
> 
> ; O. Veenstra  2003/06/29
> ; cbx total for zazzle
> ;------------------------
> Input_file_name     = raytracezazzlecbxscenescbx_zazzle_01.pov
> Output_File_Type    = N
> output_file_name    = raytracetile_colorfull_7800_5200_v31
> 
> Library_Path        = raytracezazzlecbxscenes
> 
> Width               = 7800
> Height              = 5200
> 
> Quality             = 9
> 
> 
> ; anti alias options
> ; ------------------
> 
> antialias               =    On
> antialias_Threshold     =    0.5
> 
> Sampling_Method         =    2
> Jitter                  =    Off
> 
> display = no
> 
> 
> 
I can't tell about the added black lines. It can depend on the kind of object you are
using.
For the jaggyness, it's due to the altered antialias used.
With v3.1 and earlier, the values where clipped before the antialiasing was done.
With v3.5 and later, the clipping is done AFTER the antialiasing.
The clipping I'm talking about is when a colour component exeed 1, or is lower than 0,
and is 
brought back in the 0..1 range.
Possible workaround include:
  - reducing any ambient value, possibly down to ambient 0
  - lowering the intensity of your light(s)
  - using slightly darker pigments
  - if using specular or phong, lowering the intensity of the highlight
Personaly, I prefer my metalic textures with the ambient set to zero, they look better
acording to 
my taste. (you have to do this if you want to use them in a radiosity scene,
otherwise, your metals 
will emit light...)

-- 
Alain
-------------------------------------------------
BACHELOR: A man who never makes the same mistake once.


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From: Christoph Hormann
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 26 Dec 2005 14:06:50
Message: <43b03f4a$1@news.povray.org>
Tim Nikias wrote:
> 
> I myself am not as happy with the new handling either, and hope that in
> future version you might choose which behaviour you want (the new handling
> is more realistic, but, as you noticed, sometimes defeats the purpose of
> antialiasing that we want/need).

For that matter note the latest version of MegaPOV contain a patch 
offering more flexibility there.  See the 'tone_mapping.pov' sample scene.

-- 
Christoph Hormann
http://www.imagico.de/


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From: olafcbx
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 26 Dec 2005 17:30:00
Message: <web.43b06e053a163c4cca4e75860@news.povray.org>
"olafcbx" <ola### [at] wxsnl> wrote:
> Hi,
>
> I retraced a scene I did previous with with V3.1 with V3.6 (for Windows).
> I rendered a lot faster, but I am not happy with the quality.
> The Anti aliassing looks worce, and I noticed strange black lines on edgeds
> that I havent seen before.
>
> As the images are 7800 x 5200 pixels I do not include them :-)
>
> This is the .ini file I used for both V3.1 and V3.6
>
> I re-rendered the same scene with 3.1 and 3.6 again to be sure and used
> Paint Shop pro to compare side-by-side.
>
> Is there a known problem or a fix?
> Or can I no longer expect the same results without a modification in the
> ..ini file?
>
> Thanks,
>
> Olaf
>
> ------------- the ini file used ----------------
>
> ; O. Veenstra  2003/06/29
> ; cbx total for zazzle
> ;------------------------
> Input_file_name     = raytracezazzlecbxscenescbx_zazzle_01.pov
> Output_File_Type    = N
> output_file_name    = raytracetile_colorfull_7800_5200_v31
>
> Library_Path        = raytracezazzlecbxscenes
>
> Width               = 7800
> Height              = 5200
>
> Quality             = 9
>
>
> ; anti alias options
> ; ------------------
>
> antialias               =    On
> antialias_Threshold     =    0.5
>
> Sampling_Method         =    2
> Jitter                  =    Off
>
> display = no

I put some examples of the quality problems I found on the following site:

http://home.wxs.nl/~olafveen/povray/povray.html

Here you can see the results of both V3.1 and V3.6

Olaf


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From: Warp
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 27 Dec 2005 10:39:57
Message: <43b1604d@news.povray.org>
For the antialiasing problem note that neither v3.1 nor v3.6 handle
it properly. They both have problems.
  The antialiasing used in v3.1 doesn't work correctly when there are
ultrabright but very small (sub-pixel) details. The v3.6 antialiasing
doesn't work correctly with ultrabright larger areas (over pixel size).
The latter was a "fix" to the former, but it only introduced another
problem, so it wasn't really a solution.

  In the vast majority of cases the older antialiasing gives better-looking
results than the newer. AFAIK some kind of new method (perhaps similar to
the tone mapping in megapov) which would fix both problems is being studied
for v3.7.

-- 
                                                          - Warp


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From: Zeger Knaepen
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 28 Dec 2005 16:04:50
Message: <43b2fdf2$1@news.povray.org>
"Warp" <war### [at] tagpovrayorg> wrote in message 
news:43b1604d@news.povray.org...
>   For the antialiasing problem note that neither v3.1 nor v3.6 handle
> it properly. They both have problems.
>   The antialiasing used in v3.1 doesn't work correctly when there are
> ultrabright but very small (sub-pixel) details. The v3.6 antialiasing
> doesn't work correctly with ultrabright larger areas (over pixel 
size).
> The latter was a "fix" to the former, but it only introduced another
> problem, so it wasn't really a solution.
> 
>   In the vast majority of cases the older antialiasing gives 
better-looking
> results than the newer. AFAIK some kind of new method (perhaps similar 
to
> the tone mapping in megapov) which would fix both problems is being 
studied
> for v3.7.

I still think a bloom-effect would be the best and most realistic 
solution :p

cu!
-- 
#macro G(b,e)b+(e-b)*C/50#end#macro _(b,e,k,l)#local C=0;#while(C<50)
sphere{G(b,e)+3*z.1pigment{rgb G(k,l)}finish{ambient 1}}#local C=C+1;
#end#end _(y-x,y,x,x+y)_(y,-x-y,x+y,y)_(-x-y,-y,y,y+z)_(-y,y,y+z,x+y)
_(0x+y.5+y/2x)_(0x-y.5+y/2x)            // ZK http://www.povplace.com


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From: Warp
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 29 Dec 2005 03:37:12
Message: <43b3a038@news.povray.org>
Zeger Knaepen <zeg### [at] povplacecom> wrote:
> I still think a bloom-effect would be the best and most realistic solution :p

  Hmm... Did I say something which can be understood as opposing such
technique? Your answer sounds as if I had given argument against it.

-- 
                                                          - Warp


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From: Zeger Knaepen
Subject: Re: Quality difference btw V3.1 and V3.6
Date: 29 Dec 2005 03:44:02
Message: <43b3a1d2$1@news.povray.org>
"Warp" <war### [at] tagpovrayorg> wrote in message 
news:43b3a038@news.povray.org...
> Zeger Knaepen <zeg### [at] povplacecom> wrote:
> > I still think a bloom-effect would be the best and most realistic 
solution :p
> 
>   Hmm... Did I say something which can be understood as opposing such
> technique? Your answer sounds as if I had given argument against it.

oh, no, not at all!  But you didn't mention bloom, so I thought I would 
:)

cu!
-- 
#macro G(b,e)b+(e-b)*C/50#end#macro _(b,e,k,l)#local C=0;#while(C<50)
sphere{G(b,e)+3*z.1pigment{rgb G(k,l)}finish{ambient 1}}#local C=C+1;
#end#end _(y-x,y,x,x+y)_(y,-x-y,x+y,y)_(-x-y,-y,y,y+z)_(-y,y,y+z,x+y)
_(0x+y.5+y/2x)_(0x-y.5+y/2x)            // ZK http://www.povplace.com


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