Gilles Tran wrote:
> 
> [...] but it's really
> not simple, and there's a lot of standard landscapes that I still have to
> see in hobbyst's 3D (like
> http://gallery.euroweb.hu/art/c/claude/2/11paris.jpg).
> Perhaps I should only say that the current limitations in CG landscaping are
> much more important than for indoors scenes or "package-shot" scenes. I've
> seen a lot a photorealistic scenes of this latter kind but very few
> photorealistic landscapes (and again, I'm not saying that photorealism is a
> good criteria to judge an image).

I also think that most CG landscapes you see are often of lower quality
than indoor scenes, but i don't see much of a difference between hobbyist
and professional work.

To me it seems the key element is 'control' here.  Landscape elements,
both the terrain as well as vegetation, clouds and other things have such
a high complexity that creating them without significant algorithmic
elements is nearly impossible.  But the classical techniques of 3d
modelling (patches, metaballs, etc.) are totally human controlled and lack
these elements.  Purely computer generated structures without any
possibility for human influence on the other hand will also not be of much
use.

Christoph

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3D9B6139.4017B9DB@gmx.de...
> I also think that most CG landscapes you see are often of lower quality
> than indoor scenes, but i don't see much of a difference between hobbyist
> and professional work.

Professionals have access to hardware, software, shaders, texture libraries
etc. that hobbysts don't have, and they also have the training. If you've
seen the "Time machine" (not a very good movie so you may not have missed
much) there are some landscape morphing sequences that are quite impressive,
and all the vegetation was created with xfrog. I really don't think I could
do the same.
Water textures and surfaces is also an area where pros using specific
shaders and plug-ins really have an advantage over hobbyists (I'm talking
final images, not demos).

> To me it seems the key element is 'control' here.  Landscape elements,
> both the terrain as well as vegetation, clouds and other things have such
> a high complexity that creating them without significant algorithmic
> elements is nearly impossible.

Yes, this is really the point actually. Any natural element or object is
really hard to reproduce realistically and the closer it is to the camera
the more difficult it is to model. We can only have an "impressionistic"
approach with a lot of simplifications. In a classic landscape image, the
ground, for instance, is already a problem : how to maintain realism on the
parts closest to the viewer without overloading the parts in the background
with unecessary details, and still maintain the continuity between
foreground and background ? There are techniques for that, but your typical
height-field won't be very useful (gigantic ones would be necessary), so
it's isosurfaces (slow, with difficult control of feature placement) or some
clever tiling with plants or other objects to mask the discontinuities. And
some pattern repetition will be necessary etc. Silly as it seems, it's a
difficult issue when I work on landscapes.

G.


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Gilles Tran wrote:
> 
> [...]
> 
> Professionals have access to hardware, software, shaders, texture libraries
> etc. that hobbysts don't have, and they also have the training. If you've
> seen the "Time machine" (not a very good movie so you may not have missed
> much) there are some landscape morphing sequences that are quite impressive,
> and all the vegetation was created with xfrog. I really don't think I could
> do the same.

I did not see 'Time machine' yet, but i saw a trailer with one of those
landscape morphings.  You are surely right about the available hardware
and software resources but to me it seems the artificial landscape
sequences from movies are commonly produced with a lot of human work and
quite few algorithmic modelling (except for the detail structure which is
often hard to distinguish from bump mapping if you view a movie) and
usually won't be suited for a high quality still render.

> Water textures and surfaces is also an area where pros using specific
> shaders and plug-ins really have an advantage over hobbyists (I'm talking
> final images, not demos).

I think water textures are really nothing where hobbyists and espacially
POV-Ray has to hide from the professionals.  POV-Ray is capable of
creating fairly realistic water materials - of course often quite slow,
but also of much higher quality than a lot of water you can see in
professional work (which has often a quite metal like appearance)  The
real problem about water is the geometry, things like breaking waves,
waterfalls, etc.  Here the available hard- and software of course plays a
significant role.

> Yes, this is really the point actually. Any natural element or object is
> really hard to reproduce realistically and the closer it is to the camera
> the more difficult it is to model. We can only have an "impressionistic"
> approach with a lot of simplifications. In a classic landscape image, the
> ground, for instance, is already a problem : how to maintain realism on the
> parts closest to the viewer without overloading the parts in the background
> with unecessary details, and still maintain the continuity between
> foreground and background ? 

You should really try out isosurfaces, controlling their shape in detail
is indeed not that easy, but it all comes back to the speed problem in the
end - if rendering was faster modelling would be easier.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
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3D9C1FCA.489FCDA4@gmx.de...

> professional work (which has often a quite metal like appearance)

Real ocean waters can look very metallic under certain lighting conditions.
Water is a weird material indeed, I can't help noticing how solid it looks
every time I'm on a boat.

> real problem about water is the geometry, things like breaking waves,
> waterfalls, etc.  Here the available hard- and software of course plays a
> significant role.

Any water surface that it isn't 90% flat is hard in POV-Ray. Ripples are OK
but otherwise, it's more an artistic impression of water than anything else.
Every tried to make a gently rolling ocean water ? I remember trying to copy
some from photographs and never succeeded in getting both the geometry
(isosurfaces) and the texture right at the same time. The killer render
times didn't help for sure.

> You should really try out isosurfaces, controlling their shape in detail
> is indeed not that easy, but it all comes back to the speed problem in the
> end - if rendering was faster modelling would be easier.

A good solution I've been using is the function-based height field, because
one can use low-resolution versions during tests and tune it according to
distance and it renders much faster that regular isosurfaces. Regular isos
may be needed for close-up though, you cant' beat the detail.

G.


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Gilles Tran wrote:
> 
> Real ocean waters can look very metallic under certain lighting conditions.
> Water is a weird material indeed, I can't help noticing how solid it looks
> every time I'm on a boat.

Well, actually i was more referring to smaller water surfaces like lakes
or puddles.  Anyway in nearly all situations the interaction of the light
with the water plays an important role.  In my experience the solid look
is limited to looking at the water at a fairly shallow angle against the
light (like a typical sunset image).

> Any water surface that it isn't 90% flat is hard in POV-Ray. Ripples are OK
> but otherwise, it's more an artistic impression of water than anything else.
> Every tried to make a gently rolling ocean water ? 

Have you seen:

http://www-public.tu-bs.de:8080/~y0013390/pov/water/water_inc.html

Of course as soon as the waves are strong enough to break it starts
looking artificial.  The major drawback is that it is a slow function,
therefore using it in an isosurface is quite a pain and a heightfield is
bad for a large water surface too of course.  A possible solution would be
creating a mesh with varying detail level.

> A good solution I've been using is the function-based height field, because
> one can use low-resolution versions during tests and tune it according to
> distance and it renders much faster that regular isosurfaces. 

But as soon as you have some steeper parts in the terrain you tend to get
quite serious problems with heightfields.  And increasing the resolution
then often makes in worse and not better.

Christoph

-- 
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3D9C6AA8.27264063@gmx.de...

> http://www-public.tu-bs.de:8080/~y0013390/pov/water/water_inc.html

Yes of course and it's amazing... In fact I even tried it once but it's only
usable on relatively small surface of water. What I'd like is the sort of
stuff shown here http://www.areteis.com :-) but until all these companies
wise up and give me their software for free this is not going to happen.

G.
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Gilles Tran wrote:
> 
> Yes of course and it's amazing... In fact I even tried it once but it's only
> usable on relatively small surface of water. What I'd like is the sort of
> stuff shown here http://www.areteis.com :-) but until all these companies
> wise up and give me their software for free this is not going to happen.

Now that i saw the Titanic picture on the main page there - this was
exactly one of the examples i considered as looking too metallic.  The
wake in that scene is of course very impressive but the material does not
seem that good.  See also:

http://www.areteis.com/products/renderworld/gallery/cool_sun.htm
http://www.areteis.com/products/lightwave/psunami/gallery/render3.htm
http://www.areteis.com/products/xsi/psunami/gallery/phoenix3.htm

for bad examples in that concern.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______

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