What is the right thickness for surface of water?

[Cirosan]

Hi everyone, hi Vlado

What is the right thickness for surface of water? For example.. to simulate correctly a pool.
Sometimes I get good results with 2-3cm thick object..
other times I dont' use thickness but just a simple plane (but objects under the water looks too deformed!)

But, generally... what is the physical correct approach for V-Ray?

1) creating an object "surface of water" with a specific thickness
2) creating an object "surface of water" without thickness (simple plane)
3) creating a box imitating the volume of the water?

Thank you

[stevesideas]

Im not sure you would consider water to have a thickness when using vray. I would personally just use plane/mesh ...the underlying geometry and shaders should look physically correct if the correct IOR and caustics are applied. I might be completely wrong of course

[Undersky]

Yeah, you shouldn't have a thickness for the surface. Consider it a whole volume. If you have thickness, then the rays will stop refract at the "end" of the thickness, so to speak, which is wrong. So just use a single-sided surface.

[PIXELBOX_SRO]

right but if you have a liquid as a volume inside a bottle for example? refract rays dont stop at the end if you give them enough "bounces"

[Cirosan]

Hi Guys
I tried both solution...
1) simple plane should be corret.. but I get too distorted results
2) small thickness gave me good result but i think is not correct (and caustics are not strong as in reality)

On the other side small thickness works fine.... also in the real world!
take a look to this page, it's a real installation:
http://themodernartist.wordpress.com...swimming-pool/

so the question is mostly related to "v-ray"
so what is the correct approach?
thanks

[rivoli]

On the other side small thickness works fine.... also in the real world!

yes, well, but that's not a proper swimming pool, is it.

a simple plane with no thickness should work just fine, objects underwater should look correctly deformed by the refraction (as it happens to real objects in real pools). if you built a cube of solid water, you'd have to have it intersecting the pool geometry anyway, so the result would be the same as having a simple plane. and anyway, objects would be inside it, and would be refracted through single face of the cube's geometry which is the surface of the water. once again, same result as with a single plane.

liquids in glass are a bit more complicated, but for a pool a simple plane will do just fine.

[Cirosan]

I will explain my doubt better with an image
What I'm trying to say is...

I'm agree with you about that the plane can be a good approximation.

BUT I always observed that the plane produce strange deformations.
Look this image and also real pics as reference...


Don't you think these deformations are too strong?

I don't know the answer... I just observed that.
Could be that V-Ray doesn't "like" this kind of approximation for million reasons...
Please Vlado, may I know your opinion about?

Thank you so much



PS
people are 10mt from the camera
spheres are 20mt from the camera
end of the pool is 25mt from the camera

[rivoli]

actually I'd say the rendered image is correct, and that's what I would expect to experience in real life too.

edit:
here's a reference, look at the people there, and the bottom of the pool. if it wasn't for the effect of the refraction through the water, one might say the pool is only a few inches deep..

http://www.lofosapartments.com/wp-co...2/JFS_7481.jpg

[Cirosan]

Thank you Rivoli