Simon de Vet wrote:
--snip--
> 
> I've looked at other people's cloud techniques, and they all use 3-d to generate
> 3-d looking clouds. Some use media, or isosurfaces, or stacked planes, but all use
> actuall objects.
>
--snip--

If I may beat my own drum for a sec, I posted a non-media 2D cloud
example not too far back. The method provided for some 3D lighting
effect. For the results, the rendering times were pretty fast. I'll take
the liberty of sticking in another example my pigment clouds below.
(This was from an effort to copy the technique from the TGLTLSBFSSP page
which you mentioned).

I have always thought that simple bump mapping should do the trick of
providing the correct shadows to pigment. So far though, I have had very
little success with it in POV. Not sure why ...

Abe

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Attachments:
Download 'clouds_simple.jpg' (33 KB)

Preview of image 'clouds_simple.jpg'

Regarding the clouds at Hugo Elias' page, he _does_ apply cloud shading 
via bump mapping in the snippet of pseudo-code at the end. You can also
see it in the example image.

Abe

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"Paul Vanukoff" <van### [at] primenetcom> wrote in message
news:39a71fe1@news.povray.org...
>
> AWSOME ROLEX! even.

I guess I should post another of my stern warnings against posting photos
and trying to pass them off as POV.

[ ;-) Good work]

--
Eric
--------------------
http://www.datasync.com/~ericfree
--------------------
"I don't like it, and I'm sorry I ever had anything to do with it."
- Erwin Schrodinger talking about Quantum Mechanics.

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Abe wrote:
> 
> Regarding the clouds at Hugo Elias' page, he _does_ apply cloud shading
> via bump mapping in the snippet of pseudo-code at the end. You can also
> see it in the example image.
> 
> Abe

Seems you are right, but the effect is not very strong.  I think simple bump
maps probably are not sufficient in many cases like this:

http://www.wolkenatlas.de/wolken/wo12625.htm

Of course these are somewhat extreme, but the general type of those clouds is
very common.  

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Christoph Hormann wrote:
> 
> Seems you are right, but the effect is not very strong.  I think simple bump
> maps probably are not sufficient in many cases like this:
> 
> http://www.wolkenatlas.de/wolken/wo12625.htm

An understatement.

> 
> Of course these are somewhat extreme, but the general type of those clouds is
> very common.

...and very desirable ;)

Abe

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Why are image maps so frowned upon in the POV community?  Almost all of
the big wig renderers use them solely.

GrimDude wrote:
> 
> Image_map and IRTC? Bite your tongue!
> 
> Grim

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Simon de Vet <sde### [at] istarca> wrote:
> I've looked at other people's cloud techniques, and they all use 3-d to
generate
> 3-d looking clouds. Some use media, or isosurfaces, or stacked planes, but
all use
> actuall objects.
[snip]
> I'm attaching a test image I made before I gave up on this technique, due
to time
> limitations. It's a very early image, with no pseudo-3-d effects, but it
shows how
> pigments can be used to create the shape of distant thunderclouds. It's
all one
> pigment, generated with the 'pigment control trick' and MegaPov's spline.

Yes, I think this method does hold a lot of promise.  A while ago I put
together a few animations of various types of clouds, which do include
sun-shading (see the Current Projects page at
http://www.geocities.com/ccolefax/projects.html).  The code is all quite
basic POV 3.1, and I've parametised most aspects of the clouds.  I think the
trick is to find pigments that look effective at high resolutions...

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The 3D structure of clouds can be seen if they are close and moving quickly in strong
winds.  I saw a thunderhead move over and away from us and it looked very 3D.  Some
dark clouds passed in front of it with visible motion.  The thunderhead was also
visibly swelling.
Brendan

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Nick Portelli wrote:

> Why are image maps so frowned upon in the POV community?  Almost all of
> the big wig renderers use them solely.

It's my personal belief that when I'm rendering, I'm not trying to win a
race, or stick to rules, but just make a nice looking picture. If an
imagemap can produce good results (as the comments have shown), and it
suits my situation, then I will use an imagemap. If I need more
flexibility, then I will use procedural textures.

There are no correct and incorrect tools, merely tools that are, or aren't
suited to the job. There is nothing more honourable in using a penknife
when a chainsaw is better suited to the job, and vice-versa. Both have
their uses, and there is no reaosn for conflict.


Simon

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"Nick Portelli" <por### [at] pilotmsuedu> wrote in message
news:39A9A67D.29090A1A@pilot.msu.edu...
> Why are image maps so frowned upon in the POV community?  Almost all of
> the big wig renderers use them solely.
>

It's not the image maps (a valid texturing process after all), but the
images (photos). Photographs should hold only a *very* minor role in any
rendering, particularly in the IRTC, where you want to set your work apart
from all the others. Image maps should be used *only* when nothing else will
do (as the Pov docs state). :)

There are a million valid uses for image maps, even in the IRTC. I would
not, however, use one as in this scene. I intend no offense upon Simon. I am
merely stating my opinion and advice.

Nothing says the big wig renderers are doing anything right. Those guys get
you hooked on image mapping, so they can sell you expensive texture
libraries. Thank the Pov gurus that you have procedural functionality!

Oops, inspiration has struck again. Ciao!

Grim

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