Hey Guys was wondering if i could get some help here i have a plane with a Water material and i keep getting some blue faces when theres an object under it. Dont know exactly whats causing this ive tried playing with the settings but no luck. Maybe someone can comment. Also keep in mind its only the objects close to the plane once they get lower the blue dissapears.
Thanks so much.
Try having the water as a closed mesh, not a plane, especially if you use fog.
I can’t think of anything else…
Secondary rays bias ?
=(
tried it its still happening lol.
Do you have any environment overrides?
Best regards,
Vlado
No
Nope i have them at Default i even tried overiding them and using vraysky etc. but i get the same results.
Would you mind posting a scene stripped down to the bare minimum, so to have a look at it?
sure
yea sure give me a sec! thanks for the fast response!
Dude my ftp is down right now i cant get it on. anywone know any free file sharing services.
Well I have had a quick look, and its certainly the fog thats causing it. If you turn it off the problem goes away.
Even with default vray materials on everything and using just brute force GI some parts of the mesh are bright blue. I even put in a few teapots and boxes and some of those get affected as well.
Even placing a single plane over the objects does the same thing.
Also happens with just a direct light for the lighting. And even after clearing up the vraylog errors.. it still happens.
Im just a little stumped.
Certainly is to do with the fog…but why.. bug… Vlado?
I took a look as well and came to the same conclusion daforce did (a bug?). Only thing I can add though is that you can control the “depth” of the blue surfaces by adjusting the shadow bias, which was at .2m which translates to 7" which I think is too big (for me it’s normally .2**"**). Adjusting it to .005m clears up most of the blue but it is still there in a few spots.
I find it realistic though, if you stay enough time underwater sure your face will turn blue too.
Sorry, couldn’t resist 
But then the blue faces would be down at the bottom of the pool since you’d sink 
Look at the posted image, the bottom is pale blue as expected 
k k, thats my share of morbid humor for today 
I have had this experience that when an object is just a plane ( without any faces on the backside )
the fog color becomes difficult to control. My guess is that probably the rays requires a face on the
backside, as the amount of fog greatly depends on the thickness of an object apart from the intensity
setting.
But in my case the whole scene behind that object turned into a deep tone of the fog color. Whereas
this is quite new to me … only the surface on the box is deep blue and the rest of the pool still looks
quite right!
Looks like a bug 0.O
best regards,
if you make the water properly, ie: a box solid that goes through the containing walls, does it work?
i’ve never found water to look right if its not made ‘physically correct’
I *think* i fixed it.
I changed the shadow bias for the sun to 0.001, gave thickness to the water mesh (shell modifier), and fixed the fog material settings.
For the final render i also added caustics, as a swimming pool without them is not complete XD
As a side note, I also made the sun invisible, as it would lead to the usual ringed over bright spots with the filter used.
http://rapidshare.com/files/79885570/Test\_scene\_Stripped\_Lele\_001.rar.html
I was wondering, if it makes any difference to have a perfectly modeled water mesh as water for example in a pool, or just to have the top plane.
It is even hard to grasp what would be a perfect mesh here. There are two situations, where having faces other then the top ones makes any difference, and imo both will lead to rendering artifacts, or imperfections. First you can have a small gap between the pool surfaces, and the water, but in this case you’ll get an unwanted refraction where irl you normally wouldn’t.
Second, you can model the water surfaces coplanar to the pool walls, but I think this is one thing to be avoided.
In any other situation, rays would hit the pool walls first and will never intersect our additional water mesh faces, thus making them unnecessary.
So, considering refraction, I think it makes very little difference, and in my opinion, having only the top faces gives a more accurate solution. Same goes for fog too, Rays entering trough the top faces will start accumulating fog saturation as they travel, and eventually hit the pool walls and since the walls are opaque, it will also terminate fog saturation gain. If we have a volumetric water model, separated by a small gap from the pool, the fog gain termination will occur slightly sooner, when the ray exits out water mesh, but again this makes very little difference imo.
Of course, all this applies only if the water meets a completely opaque surface, if another refractive surface is involved, an accurate and intersecting mesh is required.
Correct me if I’m wrong, because I’m concerned about this.
Best regards,
A.
In VRay contact surfaces are correctly calculated.
A “good mesh” is as you see in the file i posted: a closed volume.
Slightly larger than the pool, and intersecting its walls.
In fact, think of a glass with some liquid in it.
You’d model that liquid as a plane?
