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Histograms of the different noise_generators, one with the granite
pigment, the other with pigment{function{f_noise3d}}. Images rendered
to gamma=1.
Maybe usefull in the docs, section "6.7.12.4".
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
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Attachments:
Download 'all_noise.jpg' (16 KB)
Download 'all_granite.jpg' (22 KB)
Preview of image 'all_noise.jpg'
Preview of image 'all_granite.jpg'
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"ingo" <ing### [at] home nl> wrote in message
news:Xns### [at] povrayorg...
> Histograms of the different noise_generators, one with the granite
> pigment, the other with pigment{function{f_noise3d}}. Images rendered
> to gamma=1.
> Maybe usefull in the docs, section "6.7.12.4".
Wow, that really exposes what's going on there. The spike along the far
right edge of the first one looks really out of place, unless that's some
flaw in your images.
Bob H.
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Nope, that's now a flaw, there's also a spike on the far left of the same
histogram. That's caused by the plateaus of black and white in
noise_generator 1.
I had almost solved the problem with version 3.1 bozo earlier, it involves a
lot of probability, but it *is* possible to remove the plateaus and still
keep the pattern looking very similar. I sort of gave up when I heard that
version 3.5 would have the new noise generator, but maybe I should look back
into that...
- Slime
[ http://www.slimeland.com/ ]
[ http://www.slimeland.com/images/ ]
"Bob H." <omn### [at] msncom> wrote in message
news:3bd43250$1@news.povray.org...
> "ingo" <ing### [at] homenl> wrote in message
> news:Xns### [at] povrayorg...
> > Histograms of the different noise_generators, one with the granite
> > pigment, the other with pigment{function{f_noise3d}}. Images rendered
> > to gamma=1.
> > Maybe usefull in the docs, section "6.7.12.4".
>
> Wow, that really exposes what's going on there. The spike along the far
> right edge of the first one looks really out of place, unless that's some
> flaw in your images.
>
> Bob H.
>
>
>
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I wanted to try creating histograms myself, and my results look different. It
seems when someone wants to use f_noise3d as a random number generator, it
is important to use a big range. I used a unit circle and unit square, and I
thought the difference might be interesting..
(histograms are from 1024x1024 renderings, i reduced resolution and colors
because of file-size)
--
#macro C(X,Y)cylinder{X*x<X,0,-Y/2>.1}#end#macro U(R,X,Y)intersection{torus{.9
.1}box{-1 0rotate y*R*90}translate<X,0,Y>scale 1-z*.5}#end union{U(0,0,0)U(1,0
,0)U(2,-1,-1)U(1,1,0)U(1,1.5,-3)U(1,2,0)U(3,1,0)U(2,2,0)U(0,3,0)U(3,2,.5)C(.1,
2)C(.8,1)C(.8,-1)C(1.1,1)C(1.9,-1)pigment{rgb 10}rotate x*90translate<-1,0,4>}
Post a reply to this message
Attachments:
Download 'noise_hg.png' (30 KB)
Preview of image 'noise_hg.png'
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in news:3bd4638f@news.povray.org Elias Pschernig wrote:
> It
> seems when someone wants to use f_noise3d as a random number
> generator, it is important to use a big range.
Yes, to get repeatable[1] results I scaled the pattern down a lot.
[1] With repeatability here I mean that one should get very similar
results, independent of how the pattern is translated/rotated.
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
Post a reply to this message
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Wasn't it ingo who wrote:
> Histograms of the different noise_generators, one with the granite
>pigment, the other with pigment{function{f_noise3d}}. Images rendered
>to gamma=1.
> Maybe usefull in the docs, section "6.7.12.4".
>
>Ingo
>
It certainly shows the problem with granite textures that have been
imported from v3.1.
If you have a granite with a colour_map that used to have a colour that
kicked in at values above 0.6 (e.g. the pinkness in Pink_Granite in
textures.inc", which kicks in at 0.8) that colour just isn't going to
appear any more unless you remember to switch back to the old
noise_generator.
--
Mike Williams
Gentleman of Leisure
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in news:3bd43250$1@news.povray.org Bob H. wrote:
> The spike along the far
> right edge of the first one looks really out of place, unless
> that's some flaw in your images.
>
Here's a histogram of the same image (noise 1, f_noise3d), but without
taking the black and white pixels into acount while scaling the
histogram.
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
Post a reply to this message
Attachments:
Download 'nhist.png' (1 KB)
Preview of image 'nhist.png'
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"ingo" <ing### [at] homenl> wrote...
> Histograms of the different noise_generators, one with the granite
> pigment, the other with pigment{function{f_noise3d}}. Images rendered
> to gamma=1.
> Maybe usefull in the docs, section "6.7.12.4".
Actually, I was planning to fix the granite pattern so that it produces
similar results for all three noise generators. Any comments? Also, would
the wrinkles pattern need to be "fixed" too?
-Nathan
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Nathan Kopp wrote:
>
> Actually, I was planning to fix the granite pattern so that it produces
> similar results for all three noise generators. Any comments?
I think that's a good idea.
> Also, would the wrinkles pattern need to be "fixed" too?
>
It does not seem to produce unexpected results to me.
Christoph
--
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other
things on: http://www.schunter.etc.tu-bs.de/~chris/
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The problems with noise gen 1 have been fixed with two and three. One allows
for artistic effects not possible with the other two.
Mick
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