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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-----BEGIN PGP SIGNED MESSAGE-----
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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Version: GnuPG v1.2.2 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFAm8moqIYJdJhyixIRAhh9AJ4j6nxizpZ5uYFgzE9iPNan9RrBbwCeMKB6
JAm+mVoPr4xJc4WgTJWnBY0=
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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.

Post a reply to this message

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 :).

Post a reply to this message

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?
>
Well, I asking is there *any* syntax for aplying exterior and interior
texture to UV-mapped mesh in POV-Ray - with thousands triangles converted
from 3d modeling program, not a few triangles made for hobby. This
inside-outside separated materials is common feature in many renderers,
including raytracers. I'm afraid that POV can't do that.

I will be very happy if some of next official version will support some
common things like Angle Of Incidence, motion blur, fast (even 'faked',
interpolated, anything...) SSS..., ambient occlusion (newest version of
freeware Blender have AO, works very good...) just because I'm afraid for
the future of raytracer which I was using for a years.

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

I posted two separated answers in one message.

Post a reply to this message

anto matkovic <ant### [at] matkoviccom> wrote:
> Right question is, how I can apply interior_texture in texture_list, or I
> need some other way?

  You can't specify the interior_texture of individual triangles in a mesh.
You can only specify one for the whole mesh (at the 'mesh2' block level).

-- 
#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:
> 
> I will be very happy if some of next official version will support some
> common things like Angle Of Incidence, motion blur, fast (even 'faked',
> interpolated, anything...) SSS..., ambient occlusion (newest version of
> freeware Blender have AO, works very good...) just because I'm afraid for
> the future of raytracer which I was using for a years.

I am pretty sure if you are more happy with using blender no one here 
will feel urged to convince you not to use it.  On the other hand it 
might be a good idea to actually understand what the words you are using 
there mean.  Someone who really believes what you are writing surely has 
to wonder why it is possible to create good looking images with POV-Ray 
at all...

Unfortunately it has become a quite common attitude recently to demand a 
new feature as soon as something does not work as expected.  POV-Ray is 
not a program aimed to be as easy to use as possible at all costs.  If 
you have seriously tried to use the existing features to achieve the 
intended effect and can well demonstrate a limitation, someone familiar 
with the POV-Ray internals and the technical aspects of raytracing might 
decide to implement a new feature for this purpose.  Incidently most of 
the patches that have been written in the last years have been created 
this way, i don't remember any written because someone demanded a 
certain headword from the advertisement repertoire of commercial CG 
packages.

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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On Sat, 8 May 2004 22:26:30 +0200, anto matkovic <ant### [at] matkoviccom> wrote:
> Well, I asking is there *any* syntax for aplying exterior and interior
> texture to UV-mapped mesh in POV-Ray - with thousands triangles converted
> from 3d modeling program, not a few triangles made for hobby. This
> inside-outside separated materials is common feature in many renderers,
> including raytracers. I'm afraid that POV can't do that.

Look at http://hem.bredband.net/b230591/povray/inside_outside.png.

That's a mesh2 with 10k triangles. It's uv-mapped and has a different 
texture on the inside. Is that what you are trying to achieve?

I looked at your post in binaries.scene-files. Here's what I think you're 
doing wrong:
- Trying to use 'interior_texture' in 'texture_list'. That's not what 
'texture_list' is for.
- Using 'uv_mapping' as an object attribute. It's supposed to be a texture 
attribute.

What you need to do is something like this (copied verbatim from the scene 
shown in the link above):

object {
	#include "squared_torus3.inc"
	texture { OutsideTex }
	interior_texture { InsideTex }
	clipped_by { plane {-y, 0.5} }
	translate 0.25*z
}

The include file contains a 'mesh2', and nothing else. The clipping is 
just to show the inside of what is otherwise a closed object.



> I will be very happy if some of next official version will support some
> common things like Angle Of Incidence, motion blur, fast (even 'faked',
> interpolated, anything...) SSS..., ambient occlusion (newest version of
> freeware Blender have AO, works very good...) just because I'm afraid for
> the future of raytracer which I was using for a years.

I consider it fairly likely that AOI will appear in some future official 
version, considering that it has already been implemented and tested in an 
unofficial version.

Motion blur does not strictly require anything at all from the renderer. 
It can be done "externally", by temporally supersampling the image. Slow, 
perhaps, but it can be done.

Why should the POV team expend effort on implementing any kind of "fake" 
SSS, when POV-Ray can already do "real" SSS? I would much rather they 
spend time optimizing media rendering (and thus SSS) instead of trying to 
add some new feature that isn't really needed.
If you really want something fake, check out "sss_macro.inc" by Samuel 
Benge. Find it in 
http://news.povray.org/povray.binaries.scene-files/thread/%3C3FC5387A.5080705%40hotmail.com%3E/.

You asked about "ambient occlusion" before, in povray.general. The answer 
given then was that POV-Ray can achieve a similar effect (better even) 
with it's 'radiosity'.

I am not the least bit afraid for the future of POV-Ray.



>> Not that this has anything to do with scattering media and opacity...
>
> I posted two separated answers in one message.

I guess I did too...


---
FE

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In article <409d42bc@news.povray.org>,
 "anto matkovic" <ant### [at] matkoviccom> wrote:

> Well, I asking is there *any* syntax for aplying exterior and interior
> texture to UV-mapped mesh in POV-Ray - with thousands triangles converted
> from 3d modeling program, not a few triangles made for hobby. This
> inside-outside separated materials is common feature in many renderers,
> including raytracers. I'm afraid that POV can't do that.

I am not very familiar with the specifics of how UV-mapping works, but 
it shouldn't pose much of a problem. Meshes do work with the interior 
texture feature, and the syntax is the same as for every other object. 
However, you can't specify the interior texture for individual triangles.


> I will be very happy if some of next official version

Not in the next version, which won't have many new rendering features. 
Perhaps in later versions, and likely in some unofficial versions.


> will support some common things like Angle Of Incidence,

Already exists in a pattern patch, and can be done using one of my 
(currently unreleased) function patches. Probably won't make it into the 
official version, though features that allow you to implement an AOI 
pattern probably will eventually.


> motion blur,

Exists in an older version of MegaPOV, couldn't be updated in time for 
the new version. You can do similar effects without the patch by using 
multiple transparent copies of an object.


> fast (even 'faked', interpolated, anything...) SSS...,

This is a very complex feature, requiring much work before work on the 
implementation even starts. There are many possible ways to do it, and 
finding a good one will take some research and experimentation.


> ambient occlusion (newest version of freeware Blender have AO, works 
> very good...)

POV doesn't *need* ambient occlusion. It's a cheap hack replacement for 
radiosity, which POV already does quite well. This will most likely 
never be implemented.

-- 
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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anto matkovic nous apporta ses lumieres ainsi en ce 2004/05/08 16:26... :

> 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?
>>
>>    
>>
>Well, I asking is there *any* syntax for aplying exterior and interior
>texture to UV-mapped mesh in POV-Ray - with thousands triangles converted
>from 3d modeling program, not a few triangles made for hobby. This
>inside-outside separated materials is common feature in many renderers,
>including raytracers. I'm afraid that POV can't do that.
>
>I will be very happy if some of next official version will support some
>common things like Angle Of Incidence, motion blur, fast (even 'faked',
>interpolated, anything...) SSS..., ambient occlusion (newest version of
>freeware Blender have AO, works very good...) just because I'm afraid for
>the future of raytracer which I was using for a years.
>
>  
>
>>Not that this has anything to do with scattering media and opacity...
>>    
>>
>
>I posted two separated answers in one message.
>
>
>  
>
Be carefull with the terms used, some times, the exact same term is used 
by different programms for very different things, and different 
programms use unrelated terms to refer to the exact same, or very 
similar, thing.
Take "nurb" for example, Maya (ple) use it for "plastic" softly shapable 
objects while other, like moray, use it for something similar to a 
sphere sweep...(as far as I can tell from my experience)
Ambient occlusion looks like some faked radiosity.

Alain

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