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"William Tracy" <wtr### [at] calpoly edu> schreef in bericht
news:47461080@news.povray.org...
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> Hash: SHA1
>
> I'm starting to come up with some stuff that I want to build sand
> castles in. :-)
>
> I'm starting to wonder if all my "details" are really helping or
> hurting. Here's two renders, one with lots of yummy little patterns, and
> one that's completely flat except for the subsurface scattering.
>
Sand is - at the same time - easy and complicated to do. Imo, your renders
look well. I suppose that the technique used depends on the type of scene
one wants to build and the effect one wants to convey. This means that there
is no definitive solution, or so I experienced myself. Using crand, like
Mark says, can help, although I do not particularly like it. Perhaps using
more contrast between the "grain" colors gives even better results. That, of
course, depends on the type of sand one wants to render.
Thomas
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"Thomas de Groot" <t.d### [at] internlDOTnet> wrote:
> "William Tracy" <wtr### [at] calpolyedu> schreef in bericht
> news:47461080@news.povray.org...
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > I'm starting to come up with some stuff that I want to build sand
> > castles in. :-)
> >
> > I'm starting to wonder if all my "details" are really helping or
> > hurting. Here's two renders, one with lots of yummy little patterns, and
> > one that's completely flat except for the subsurface scattering.
> >
>
> Sand is - at the same time - easy and complicated to do. Imo, your renders
> look well. I suppose that the technique used depends on the type of scene
> one wants to build and the effect one wants to convey. This means that there
> is no definitive solution, or so I experienced myself. Using crand, like
> Mark says, can help, although I do not particularly like it. Perhaps using
> more contrast between the "grain" colors gives even better results. That, of
> course, depends on the type of sand one wants to render.
>
> Thomas
Hi
I was busy in RL those two last weeks and could not read much here. William,
your work seems very interesting. Would you mind, when achieved or partial,
sharing things so that I can integrate this nice stuff in TerraPOV?
Regards
Bruno
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William Tracy <wtr### [at] calpolyedu> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> I'm starting to come up with some stuff that I want to build sand
> castles in. :-)
>
> I'm starting to wonder if all my "details" are really helping or
> hurting. Here's two renders, one with lots of yummy little patterns, and
> one that's completely flat except for the subsurface scattering.
>
> Speaking of subsurface scattering, just a little goes a long way. I
> probably overdid the scattering media in these images, because
> everything looks like its underwater. Which is still cool. ;-)
>
> - --
> William Tracy
I like these two images, individually. Is there a way that you could merge the
materials, with the grainy one in the foreground fading to the smooth one in the
midground?
Stephen
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"Stephen" <mcavoys_AT_aolDOT.com> wrote:
> William Tracy <wtr### [at] calpolyedu> wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > I'm starting to come up with some stuff that I want to build sand
> > castles in. :-)
> >
> > I'm starting to wonder if all my "details" are really helping or
> > hurting. Here's two renders, one with lots of yummy little patterns, and
> > one that's completely flat except for the subsurface scattering.
> >
> > Speaking of subsurface scattering, just a little goes a long way. I
> > probably overdid the scattering media in these images, because
> > everything looks like its underwater. Which is still cool. ;-)
> >
> > - --
> > William Tracy
>
>
> I like these two images, individually. Is there a way that you could merge the
> materials, with the grainy one in the foreground fading to the smooth one in the
> midground?
>
> Stephen
I used a kind of 'fadeaway' technique for my snow texture for TerraPOV, and I
posted recently and test render here. It is based on the distance wrt camera
(use of spherical pattern): when near it is one texture, when far it tends to
be a plain color (or whatever else). I intend to integrate fadeaway texturing
macros like this in TerraPOV, because terrain pigments become plain colors with
distance. Something like this can be applied to sand (same problem). It can also
be used for other purposes, of course.
Currently, it is coded as:
// --------------------------------------------------------------
// Parameters:
// _color
// Color of the snow. Can be C_SNOW_COLOR_BLUEISH.
// _distance
// Distance where the texture becomes a plain color
// _scale
// Scale for the near aspect of the texture
//
#macro TP_SnowFadeaway (_color, _distance, _scale)
#local _t = texture
{
pigment_pattern {spherical scale _distance}
texture_map
{
[0 TP_FarSnow(_color)]
[.8 TP_SparkleSnow(_color, _scale)]
[1 TP_SparkleSnow(_color, _scale/3)]
}
};
_t
#end
// --------------------------------------------------------------
with TP_FarSnow() and TP_SparkleSnow() as other texture macros. This snow
texture is quite complex, but I think the result is OK.
I'll probablly define a general convenience macro with the following interface
#macro _tp_make_fadeway (_texture1, _texture2, _distance, _campos)
// use of a more generic macro with thresholds and scales
#end
If this can help...
Bruno
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Wow, this is nice!
Time ago I used this sand texture:
#declare t_sand=texture {
pigment {
granite
color_map {
[ 0.0 rgbft <0.670588, 0.505882, 0.321569, 0.0, 0.0> ]
[ 1.0 rgbft <0.941176, 0.878431, 0.792157, 0.0, 0.0> ]
}
turbulence 0.75
ramp_wave
scale 0.01
}
//finish { crand 0.1 }
}
But the one you realized is more impressive.
;-)
Paolo
>"William Tracy" <wtr### [at] calpolyedu> ha scritto nel messaggio
news:47465d91$1@news.povray.org...
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Mark Birch wrote:
> > It's useless in animations, but have you tried the 'crand' option?
>
> It works better than I expected, actually.
>
> (...and sorry for not remembering to convert those other pictures to jpg
> before uploading them.)
>
> - --
> William Tracy
> afi### [at] gmailcom -- wtr### [at] calpolyedu
>
> You know you've been raytracing too long when you can remember back to a
> time when you thought raytracing was a guy named Ray sitting at a desk
> tracing.
> -- Ken Tyler
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----------------------------------------------------------------------------
----
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"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> schreef in bericht
news:web.4746b46aee83a16ce8ba46670@news.povray.org...
> I used a kind of 'fadeaway' technique for my snow texture for TerraPOV,
> and I
> posted recently and test render here. It is based on the distance wrt
> camera
> (use of spherical pattern): when near it is one texture, when far it tends
> to
> be a plain color (or whatever else). I intend to integrate fadeaway
> texturing
> macros like this in TerraPOV, because terrain pigments become plain colors
> with
> distance. Something like this can be applied to sand (same problem). It
> can also
> be used for other purposes, of course.
>
Another possibility, I guess, would be to use the boxed or the cylindrical
patterns. Maybe cylindrical would be better than spherical in a landscape?
What do you think?
Thomas
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Looking pretty good. Sand can be a difficult thing to simulate. God idea
trying some SSS with it.
A few things you can try too.
-as stated before, maybe don't use a uniform colour, but have a patterned
varition as real sand tends to be
-maybe try different normal types: instead of granite or bumps, you may get
better result using either a solid crackle, or cells pattern. This will give
you flat surfaces with varying normals, and sharp transitions betwen rather
than the continuous transitions of other types. You can also colour (or
texture) map in cordination with the pattern used. You may need good AA though
to get nice results.
keep up the good work.
-tgq
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I've been looking at this scene:
http://www.irtc.org/ftp/pub/stills/2004-08-31/em_giza.jpg
My sand texture is already better than that ;-) but I need to look into
how the sloping sand shapes at the base of the pyramids was done. My
geometry is still pretty hacked-together.
Bruno Cabasson wrote:
> I was busy in RL those two last weeks and could not read much here. William,
> your work seems very interesting. Would you mind, when achieved or partial,
> sharing things so that I can integrate this nice stuff in TerraPOV?
Cool, is it that good? :-)
Anyway, for anyone who wants to play around, here's I have so far, minus
the heightfield. As others have pointed out, there's a bunch of ways to
improve this. :-)
You'll probably want to tweak the colors and the media (right now I have
it set up for red sand), and you'll probably have to play with scaling
the bozo map (the extra special sand grains) to fit your scene.
Finally, a heads-up that terrain with SSS can take a while to render.
:-) On a ~2GHz processor, the little bitty images I've been rendering
take about 30 seconds.
#declare sand_shape = height_field {
...
};
object {
sand_shape
texture {
pigment {color rgb <0.75, 0.25, 0.25>}
}
}
object {
sand_shape
hollow
translate y * 0.1
texture {
pigment {
bozo
color_map {
[0 color rgb <0.3, 0.3, 0.2>]
[0.25 color rgbt <0.9, 0.9, 0.6, 1.0>]
[0.75 color rgbt <0.9, 0.9, 0.6, 1.0>]
[1 color rgb <1.8, 1.8, 1.2>]
}
scale 0.005
}
finish {crand 0.03}
}
interior {
media {scattering {1 color rgb <0.15, 0.15, 0.05>}
samples 10, 10}
}
}
- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu
You know you've been raytracing too long when you can remember the 4
digit decimal equivelents to measurements down to 1 sixtyfourth of an inch.
-- David Kraics
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Thomas de Groot wrote:
> Another possibility, I guess, would be to use the boxed or the cylindrical
> patterns. Maybe cylindrical would be better than spherical in a landscape?
> What do you think?
The last time I was working on my "Alien Desert" image (which will
eventually use my improved sand...), I used a boxed pattern as
described. I had a bozo pattern for sand grains in the foreground, and
solid in the background.
The transition between the two was far enough away where you couldn't
even tell the difference between the two textures, so I don't know how
useful it would be for creating smooth transitions.
But it did make a big improvement in my render times. :-) Having bozo
all over a virtually limitless heightfield is slow. (I can't wait to see
how much slower SSS is!)
- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu
You know you've been raytracing too long when you downloaded and printed
the Renderman Interface documentation, so you'd have a little light
reading to take on holiday.
-- Alex McLeod a.k.a. Giant Robot Messiah
[Come to think of it, yours truly has done that before with the Java
documentation...]
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Trevor G Quayle wrote:
> Looking pretty good. Sand can be a difficult thing to simulate. God idea
> trying some SSS with it.
>
> A few things you can try too.
> -as stated before, maybe don't use a uniform colour, but have a patterned
> varition as real sand tends to be
Very good idea.
> -maybe try different normal types: instead of granite or bumps,
Take a peek at the code I posted farther up in the thread. Normals
aren't really helpful here, because the surface is transparent. :-(
Early on I tried normals on the solid surface *below* the SSS, but that
made the patterns only visible on the dark side of the sand dunes, which
is why my first screenshots were all backlit. :-)
Oddly enough, crand *does* work on a transparent surface. I'm still on
the fence whether that's a good long-term solution.
> You may need good AA though
> to get nice results.
Heh, you have no idea how I abuse AA. :-) I've posted images here before
with textures that look gorgeous under 0.1 AA, but which look like vomit
on the screen without AA. ;-)
- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu
You know you've been raytracing too long when you have to buy a new
computer to do your homework on because the other 5 are still rendering
that cool finale of "Godzilla meets the Julia monster ... with
volumetric lights".
00 AmaltheaJ5
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