swimming pool with windows

[waaazoo]

Hi,

I need some hints here. I need to render a swimming pool with caustics for an upcoming project. So far, it's an easy one.
But my swimming pool has also a front window and a bottom window. And there it becomes tricky. I tried several setups, but I never get a solution where all views look good.
So far, here is my best result but it's still the front window view that looks weird.

How would you setup this swimming pool scene. So far, I don't want to share how I did my setup (I will, later on), I'd rather prefer to know how you guys would create it.
I tested with Vray sun/sky and with domelight (domelight setup is much longer to render as you have to up the caustic subdivs).

Help will be greatly appreciated !

[waaazoo]

[JonasNöll]

Hi, I think there is something wrong about the front window. Right now it looks like there are 2 layers of glass with an air gap inbetween. Is that how it is supposed to be?

[waaazoo]

Hi Jonas,

Yes, two glass layers in front window. But I tried also with one big glass or only one glass layer. It doesn't change so much. What I find weird is the dark blue part we get on the left of the front window (cam2 and cam3)

[JonasNöll]

Hi, I think without a scene it's a bit difficult to figure out whats going on As this blue part appears where it should have the refraction of the sky it looks like there is possibly an override set for environment refraction. Or does the shader for the water/glass use some environment overrides? As you are refracting through multiple layers of glass and water did you make sure that the trace depth is set accordingly?

[waaazoo]

Hi,
Scene was done on Maya I'm pretty sure you are on Max, but thanks for your interest. Yes, trace depth is at 20.

Here are some more tests with some explanations. Different setups, and different results. Notice also the coloration of caustics on the ground.

- solution with inner glass object with water material looks almost ok, except top view (glass floor) and coloration of caustics on the ground
- solution with only top water surface totally wrong
- solution with water volume almost perfect except side window
- solution with water backface on windows looks good except some areas on side window and the glass floor when seen from side window.

[JonasNöll]

3ds Max or Maya, I think it's no big difference in terms of V-Ray
Hmmm interesting...
For picture 4, did you try out to enable "Reflect on Backside" within the material? Would be interesting if that has another effect.

So for picture 4 if I understood correctly you place a seperate surface in front of the inner glass wall. How about if instead of this approach you apply the water material on the inward facing face of the inner glas but leave the other parts as glas material?
So basically: water surface on the top and all glass goemetry that is in connection with water receives a water material, but only for the inward facing faces. The front and edges of the glass still use glass shader
No idea what would happen though, so I'm just guessing and throwing in another approach

[JonasNöll]

Then for tha approach with the volume, what would happen if you push out the goemetry slightly so that the volume is intersecting with the glass wall

[waaazoo]

3ds Max or Maya, I think it's no big difference in terms of V-Ray
Hmmm interesting...
For picture 4, did you try out to enable "Reflect on Backside" within the material? Would be interesting if that has another effect.

Reflect on backside is checked, and it doesn't change much when I uncheck. The difference is mostly noticeable on the water surface. I already tried that.

So for picture 4 if I understood correctly you place a seperate surface in front of the inner glass wall. How about if instead of this approach you apply the water material on the inward facing face of the inner glas but leave the other parts as glas material?
So basically: water surface on the top and all glass goemetry that is in connection with water receives a water material, but only for the inward facing faces. The front and edges of the glass still use glass shader
No idea what would happen though, so I'm just guessing and throwing in another approach

Yes, you understood correctly. Putting a water material on the inboard facing faces of the glass wall doesn't work either. Well, it works in some way for the glass/water look, but messes up the caustics outside of the pool (on ground).

[JonasNöll]

Hi, alright, and what happens if making the volume of the water intersect slightly with the glass walls?

[waaazoo]

This is now a test with water intersecting with walls and glass, as you suggested. In my mind it was some "dirty" modeling, but, in fact, it makes sense as ray leaves the water volume and comes into glass and then leaves to air.
I changed the design a little because I wanted also to see what happens with a glass wall. I thing that curved glass has to be avoided
Normally, these glass walls are done with laminated glass (two or three glass layers with inter layered polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), or Thermoplastic Polyurethane (TPU), but this would make too much bounces.

what do you think ?

[JonasNöll]

I think that looks much better! The only question for me would be the part where the glas wraps around and we see it reflecting back the inside of the pool and doesn't show any transparency (pic 2+3), but I think I seen this effect sometimes in huge aquariums where you can't really see back out of the aquarium in case the glass wraps around. So maybe its physically accurate
In pic 3 something is strange with the floor windows, it looks like there there is some geometry missing.

[waaazoo]

Yeah, I think rounded glass corners have to be avoided.
Here is a video of three test animations. The last one is with the latest setup (water intersecting with walls and glass). I think it looks quite ok. I should do the same with only a straight glass wall.

https://vimeo.com/427671255