Lance Birch wrote:

> > Hey, wait, it's "Internet Raytracing Competition", not "Internet Scanline
> > Competetion"! They've been cheating!
>
> Read the rules and you'll find otherwise... and besides, MAX has a
> raytracer.

I know, it was a joke

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In article <3990051b@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   Let me assure you that it's a LOT more difficult to get a good image 
> with pure OpenGL (without using any modeller) than with povray 
> (without using any modeller).

As someone just learning OpenGL, I can agree with that...OpenGL is a 
low-level graphics API, not a scene description or scripting language. 
:-)
If you want things like realistic lighting, reflections and refraction, 
you have to implement it yourself. Even simple transparence takes some 
extra effort.

Currently, the most complex thing I have done is a particle system 
simulating a bunch of skyrockets.

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I've yet to see POV used for television.  3DS MAX is used quite frequently
by Hollywood.  The animated series "Sherlock Holmes in the 22nd century" was
created with 3DS MAX.

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I knew that this statement would start quick answers.
The great thing about 3DSMAX is that its modelling capabilities allow
almost anything.
In my opinion ( and that's mine only), only Rhino does better.
Of course it's all a question of how well you know the deepest recesses
of the modeller/software.
Maya is said to be good as well, but it's a lot harder to master.

But when it comes to render quality, I still think that POV ( and Megapov
with its new features : photons & isosurfaces ~~shaders a la BMRT) is
better for still pictures.
3DSMAX is great for animation.






> > You can model easily virtually anything you like with it, but in my
> > opinion the 3DSMAX renders do not match the quality of POV.
>
> That's a bold statement Fabien!  I've seen some very impressive stuff
> from 3DSMax (and it better be good for what they charge).  Of course,
> I've seen some great POV stuff too...
>
> --
> Doug Eichenberg
> http://www.nls.net/douge
> dou### [at] nlsnet

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Warp wrote:
> Lance Birch <-> wrote:
> : Because it's generally thought by the judges that not enough effort was
put
> : in to produce the result.  A little like the way people using Maya and
> : rendering on Origin 2000 servers are thought to have an unfair
advantage.
>
>   Let me assure you that it's a LOT more difficult to get a good image
with
> pure OpenGL (without using any modeller) than with povray (without using
> any modeller).

I didn't say anything about OpenGL, I was talking about Maya and the way
higher end graphics solutions weren't as favourably marked in a lot of cases
in comparison to cheaper solutions.

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POV-Ray makes pictures by shooting rays from the camera into the scene
but how do scanline renderers create images?
Brendan

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They work usually, from my limited understanding, by building a Z-Buffer of
the scene and then sampling the Z-Buffer for each pixel to determine the
object and normal of the pixel (well, normal of the surface of the object in
the pixel) and then using standard lighting techniques to figure out how the
surface is lit and then passing the information over to the shader which
determines the correct color at that point (in MAX all information such as
surface normal is also sent so the shader can make use of that information
too, for example, a normal-dependant texture such as X-Ray).

The nice thing about scanline renderers is it's possible to save the
Z-Buffer for use as a depth map for a SIS (stereogram).  In MAX it allows
you to do a lot of things post-render as it also allows direct access to the
Object channel, Effects ID channel, Normal channel and un-scaled color
channel.  An example would be using the Object channel to apply a Video Post
effect such as Glow to just one object.

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I think this is really difficult. The only example I know
is the Cornell box: you try to reproduce a very basic scene,
(esay to model and reproduce exactly, with simple texture (only color))
and you take the photo and the 3d image, you subtract them:
if the result is perfect you get a really black image if not,
you can measure the proportion of non-black pixel and the
gap between each non-black pixel and the black color.

But to do this with "real" scene, this is not easy.
Model object can be done really precisely (one can
even use 3d scanner). But put texture exactly as there
are on the object, this is not easy even if you use image
map from this object. But this is feasible I think.
But I don't know any example.

For commercial software, I suppose this is less "scientific".
But for them, rapidity of rendering and the feeling of reality
(which is not reality) are really important. Moreover there
are also the modeler which play a crucial role in the development.

For now one of the best renderer for commercial product is Mentalray
(http://www.mental.com). It is used in Softimage and now in 3DS Max.
With it you have photon, radiosity, global illumination and 
the time for rendering are rather good.

Fabian.


> 
> Fabian BRAU wrote:
> 
> >This image just
> >show the quality of the renderer not the modeler.
> 
> I always wonder, so I ask it here, what are objective (measurable?)
> criteria to determine the quality of a renderer/tracer/..
> 
> Ingo
> 
> --
> Photography: http://members.home.nl/ingoogni/
> Pov-Ray    : http://members.home.nl/seed7/

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Andrea Ryan <ary### [at] global2000net> wrote:
: POV-Ray makes pictures by shooting rays from the camera into the scene
: but how do scanline renderers create images?

  Put in a very simple way:

  Scanline renderers project the polygons on screen, ie. they take all the
3D vertices of the polygon, project them on screen, thus converting them to
regular 2D polygons and then they draw that polygon as if it was just a
2D one.
  Of course if the polygon has texturing, it has to be done with perspective
correction for it to be right.

  There are several methods for hidden surface removal. The best one of them
is using a Z-buffer which makes a perfect removal and allows things like
space cutting (ie. two polygons intersecting).

  You can easily imagine how fast this is.
  This is the technique used by 3D accelerator cards.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Warp wrote:
> 
> Andrea Ryan <ary### [at] global2000net> wrote:
> : POV-Ray makes pictures by shooting rays from the camera into the scene
> : but how do scanline renderers create images?
> 
>   Put in a very simple way:
> 
>   Scanline renderers project the polygons on screen, ie. they take all the
> 3D vertices of the polygon, project them on screen, thus converting them to
> regular 2D polygons and then they draw that polygon as if it was just a
> 2D one.
>   Of course if the polygon has texturing, it has to be done with perspective
> correction for it to be right.
> 
>   There are several methods for hidden surface removal. The best one of them
> is using a Z-buffer which makes a perfect removal and allows things like
> space cutting (ie. two polygons intersecting).
> 
>   You can easily imagine how fast this is.
>   This is the technique used by 3D accelerator cards.

Finally!

Someone explained what scanline rendering is, instead of just saying:
"it's crap! raytracing is better".

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