Probably old question :)

- I trying to do SSS with media on Mesh2 - it works, but I simply can't do
apsolute non-transparent SSS, even with tons of intervals - object have some
very thiny details, like a ears. Is there some workflow (for relative fast
rendering:), maybe with photons?

- How to apply interior_texture to mesh2? The same settings works perfectly
with POV solids, but with mesh2, nothing... Maybe I'm a stupid :) or I
didn't laying hands on POV in a few last years.... My mind is probably in
features of POV 3.1...

Thanks in advance....

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anto matkovic <ant### [at] matkoviccom> wrote:
> - How to apply interior_texture to mesh2? The same settings works perfectly
> with POV solids, but with mesh2, nothing... Maybe I'm a stupid :) or I
> didn't laying hands on POV in a few last years.... My mind is probably in
> features of POV 3.1...

  There are two types of primitives (ie. surfaces) in POV-Ray: Those with
a defined interior and those without.

  Their difference is that for a primitive with a defined interior for any
point in space you can ask whether it's inside that primitive or not
(and in fact the POV-Ray SDL has such a function: inside()).

  Meshes belong to the second category: They do not have a defined interior.
You can make a mesh to guess at its own interior by specifying an
inside_vector (the name of this keyword is admittedly confusing because
it describes its goal and not what the specified vector actually does).

  Curiously, however, interior_texture uses (AFAIK) a completely different
method for finding out which side of the surface is facing outside and
which is facing inside: Using the normal vector of the surface.

  All POV-Ray primitives have a normal vector (else lighting calculations
would be impossible), naturally also meshes.

  I just tried using interior_texture with a mesh with smooth triangles and
it worked ok. The side of the triangles opposite to the direction of the
normal vectors was textured with the interior_texture.
  With flat triangles the normal vector is automatically calculated by
POV-Ray. If I'm not mistaken, the order of the vertices decides which
side of the triangle is the side of the normal vector. I tested this
as well, and interior_texture worked with flat triangles ok.

  I haven't tested with mesh2, though, but there shouldn't be any difference
(after all, it's just an alternative syntax for the same primitive).
Unless there's something odd going on with the mesh2 syntax, perhaps
you are making some mistake in your code? Could you post a short
example?

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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In article <409a17fa@news.povray.org>,
 "anto matkovic" <ant### [at] matkoviccom> wrote:

> - I trying to do SSS with media on Mesh2 - it works, but I simply can't do
> apsolute non-transparent SSS, even with tons of intervals - object have some
> very thiny details, like a ears. Is there some workflow (for relative fast
> rendering:), maybe with photons?

You aren't going to get opaque media by using "tons of intervals". You 
need to increase the media density, and use a high extinction.


> - How to apply interior_texture to mesh2? The same settings works perfectly
> with POV solids, but with mesh2, nothing... Maybe I'm a stupid :) or I
> didn't laying hands on POV in a few last years.... My mind is probably in
> features of POV 3.1...

The interior_texture feature should work in exactly the same way with 
mesh2 objects as with any other object.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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>   I haven't tested with mesh2, though, but there shouldn't be any
difference
> (after all, it's just an alternative syntax for the same primitive).
> Unless there's something odd going on with the mesh2 syntax, perhaps
> you are making some mistake in your code? Could you post a short
> example?
>
Probably i do mistake with code (it's a mesh 2 with UV-mapping and
image_maps, so I probably put textures on wrong place) - POV refused to work
with interior_texture in texture_list, also with transparent texture in
texture list with both exterior and interior texture at the end of inc file
of  mesh2.

Problem is solved by faking SSS in scanline program and compositing later -
because od deadline....

I will try to post example if this really doesn't work, when I prepare model
for rules of P.B.I.
(it contains nudity).

Thanks for help.

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anto matkovic <ant### [at] matkoviccom> wrote:
> I will try to post example if this really doesn't work, when I prepare model
> for rules of P.B.I.
> (it contains nudity).

  Nudity means that the scene contains at least hundreds, if not thousands
of triangles.
  That was not what I meant. With a small example I meant a minimal scene
with a camera, a light source and a mesh2 with a couple of triangles which,
when rendered, clearly shows the effect you are talking about.
  It's much easier to study the code and suggest fixes with such scene,
and the issue can be kept in a single newsgroup (because no binary
attachments are needed).

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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anto matkovic wrote:
> Probably old question :)
> 
> - I trying to do SSS with media on Mesh2 - it works, but I simply can't do
> apsolute non-transparent SSS, even with tons of intervals - object have some
> very thiny details, like a ears. Is there some workflow (for relative fast
> rendering:), maybe with photons?


I guess that it's little bit too late for you (you mentioned deadline), 
but for future note (and self-promotion :)  those, who feel adventerous 
enough to try patched POV-Ray, could use POVMan for such purpose. See my 
posting in p.binaries.images from 2003-05-18, titled 'FSSS'.
Of course it works only with POVMan (as there is shader for such 
purpose) and it ain't perfect: it is faked (that's from where F comes) 
with respect to light-source (main light source is given as parameter), 
in some cases shadows get really messy (iirc it appears in cases, when 
object has several 'intersections' toward light source) etc. But it is 
relatively fast and totally non-transparent and in some limited cases 
could provide satisfactory results with little tinkering.

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Hash: SHA1

anto matkovic wrote:
| Probably old question :)
|
| - I trying to do SSS with media on Mesh2 - it works, but I simply
can't do
| apsolute non-transparent SSS, even with tons of intervals - object
have some
| very thiny details, like a ears. Is there some workflow (for
relative fast
| rendering:), maybe with photons?
|

	Like Warp said, you need to increase density for SSS to work on small
details. You might also want to look at the "sample_spacing" keyword
in MegaPov 0.7 which might improve your render speed a lot especially
if you have a model with both lots of tiny details and thick areas.
Look at this page for a discussion (nobody called it subsurface
scattering at the time, but it's the same thing):

http://jeberger.free.fr/mpov/mpov.html#sample

		Jerome

- --
******************************
*      Jerome M. Berger      *
* mailto:jbe### [at] ifrancecom *
*  http://jeberger.free.fr/  *
******************************
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>
>   ... means that the scene contains at least hundreds, if not thousands
> of triangles.

Actually, about 2000000 triangles :), optimizied as much is possible. I
choosed POV because this number can kill common scanline renderer, POV needs
about 500MB RAM, which is quite OK for machine with 1GB.

>   That was not what I meant. With a small example I meant a minimal scene
> with a camera, a light source and a mesh2 with a couple of triangles
which,
> when rendered, clearly shows the effect you are talking about.

There is an example at povray.binaries.scene-files - with single sphere-like
mesh ( 68 triangles)
Right question is, how I can apply interior_texture in texture_list, or I
need some other way?
When I uncoment interior_texture, about line 320, POV reports error.

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anto matkovic wrote:
> 
> There is an example at povray.binaries.scene-files - with single sphere-like
> mesh ( 68 triangles)
> Right question is, how I can apply interior_texture in texture_list, or I
> need some other way?
> When I uncoment interior_texture, about line 320, POV reports error.

What makes you think this is valid syntax?

Not that this has anything to do with scattering media and opacity...

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 01 May. 2004 _____./\/^>_*_<^\/\.______

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those, who feel adventerous
> enough to try patched POV-Ray, could use POVMan for such purpose. See my
> posting in p.binaries.images from 2003-05-18, titled 'FSSS'.
> Of course it works only with POVMan (as there is shader for such
> purpose)

Thanks!

I using POVMan before, because of 'skin' shader, later I used Ml POV,
because of similar effect of AOI, which official POV doesn't have. Even all
other renderers (Blender internal scanline, as example) can do something
with AOI.

'Faking' isn't problem, I can compose it as a layer. Speed is important :).

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