"nemesis" <nam### [at] gmailcom> wrote:
> "motorsep" <nomail@nomail> wrote:
> > Here is what they have for 3DS MAX:
> > http://www.rebelthink.com/images/natshaders/images/old/Sand_RENDER.jpg
> > http://www.rebelthink.com/images/natshaders/images/new/Sand_Daylight_HI.jpg
> >
> > How can I achive such effect with Povray?
>
> I'm guessing a heightfield, atmospheric media and scattering media inside
> the heightfield to simulate subsurface scattering will do the job.
>
> this irtc image shows sand without subsurface scattering:
> http://www.irtc.org/ftp/pub/stills/2004-08-31/em_giza.jpg
>
> some stupid media is used here:
> http://www.irtc.org/ftp/pub/stills/2005-02-28/adsub.jpg
>
> and here is a better use of atmospheric media to convey a nice effect:
> http://www.irtc.org/ftp/pub/stills/2002-08-31/tnw_icla.jpg
>
> Unfortunately, none of the pictures show scattering media inside the
> heightfield.  Like, say, inside the transparent difference of the
> heightfield against a barely scaled version of itself.  Is that possible?

~~~~~~~~~~~~

Cool, You found my crap sub image.  I've found another way to do sand that
looks good.  I'm just unable to really test it due to my raytracing pc
catching fire.

Take a Heightfield that looks like the dunes you wish to create.  Make this
like a declaration so it doesn't appear.  The reason for this is because
you want to trace the entire surface with billions of random spheres.  This
should give the effect you are looking for.  If not spheres, use cubes for a
crystal look.

When the camera is close, you can see individual sand crystals.  At a
distance it looks like dunes.  But if done right, each cube will reflect
light like sand would as well.  Just experiment with this idea and it will
work out.

Tim's idea on his iceland image works very well as well.  Use two
heightfields and fill the space between with media.  But have one
heightfield below to give the presence of ground.

Hope this helps
~Allen

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