In article <3921c60a@news.povray.org>, "Robert Jefferson" 
<bob### [at] mindspringcom> wrote:

> First, sorry about the grammar.
> Second, I have not seen to many scenes underwater and was wondering 
> how it was done.

There have been a few, but not many. The main things seem to be some 
media for light beams and distance fading(or sometimes just fog or 
fade_color) and some way of making caustics on the ground.(a partially 
transparent plane between the ground and the light source, faked 
caustics, or photon mapping)
If the surface is visible, it is a good idea to use variable reflection.


> Actually I would like to do a scene half underwater and half above 
> water. It would be of a child fishing with a pole go into the water 
> from a boat or a pier.
> Under his boat/pier is a normal size fish which is also about to be 
> eaten by a model I have of Nessy.

First, I recommend that you get MegaPOV at 
http://nathan.kopp.com/patched.htm if you have not done so already.
It includes features like trace(), isosurfaces, angle dependant 
reflection, fade_color, media sampling types, etc, which would make this 
kind of scene much easier to do.

You could use a height field or an isosurface as the water surface, the 
isosurface would be more flexible and less memory-consuming, but slower 
and harder to use.
I would use "difference" to remove an area around the camera(a sphere or 
box would do) to simulate a waterproof barrier between the camera lens 
and the water. Otherwise, you won't get a visible waterline(since the 
camera normally exists at a point). You could use the trace() function 
to make camera placement easier.
For the under-water portion, you could use a scattering media to get 
visible light rays and either absorbing media or fade_color to get the 
effect of murkyness and to simulate the partially transparent nature of 
water.
For the water surface, the best way to get good results is by using 
angle-dependant reflection, a nearly completely transparent white 
pigment(water coloring is taken care of by the media/fade_color), some 
kind of highlight(I prefer blinn or specular), and an ior(water is 
around 1.3).
Another thing which many people forget: wet surfaces usually get darker. 
You might want to use layered textures to darken wet portions of the 
scene.
Ok, I think that was about everything, I will be working on a scene to 
demonstrate these techniques(most of which I am still experimenting 
with).


> Lastly i have 2 masters degree so please dont insult my intelligence.

Sorry if my message seemed to be insulting, I did not intend it that way.

-- 
Christopher James Huff - Personal e-mail: chr### [at] yahoocom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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