Rendering Boat wake foam

[JuhaHo]

I have yet another speedboat project. I wonder how I should change my foam or light settings not to overexpose the foam. What information You would need from me.

With this set up the boat itself is underexposed and I need to fix it in Photoshop. I'm using sunlight as the light source

Everithing has default settings so where should I start tweaking the settings.

[JuhaHo]

I realized, this is the first boat project, I'm creating with VRay 6. It seems, it requires totally different render settings than VRay 5. How should I tweak the render settings? I only have VRay Sun as a light source.

I don't get it. I'm now doing test renders with my last VRay 5 boat scene. While the original VRay 5 renderings look good VRay 6 renderings look awful. So, how should I change my rendering settings in VRay 6 to get at least as good results than with VRay 5? Attached is a VRay 5 scene rendered with VRay6. With VRay 5 the boat wake looked decent, but ith VRay 6 it does not. Any Ideas

[georgi.zhekov]

Hello,

From what I can see the Particle shader is way too bright - if you make the color of the particles darker or decrease the intensity of the sun it should look better.

[JuhaHo]

Thanks,

At the moment I'm experimenting reducing the sun intensity.

It still looks somewhat awful. This looks nothing like a speed boat to me. I can't send client images having boat wake like this. How would You change my settings? The speed and hull angle are correct.

[georgi.zhekov]

Looks like your motion blur is way too strong.

You can either reduce the motion blur multipler in the Phoenix Particle Shader or reduce the motion blur settings in the Camera settings if you're using a V-Ray Physical camera or if you're not using a Physical camera, reduce the duration in the V-Ray Render Settings.

[JuhaHo]

Thanks,

Motion blur settings are pretty much the default.

[georgi.zhekov]

In the Particle Shader the Motion blur multiplier is set to 2. How about if you set it to 1 or even lower it? If your particles are moving too fast value below 1 might work better.

[JuhaHo]

Thanks,

I had already made a version with value 0.5. It is somewhat better, but I'm no yet quite there. One thing comes to my mind. Does scene units have any effect on the result? I of course work by using millimeters. Does the foam particle shader require any scaling?

[georgi.zhekov]

Okay, try even lower and it should look better.

Regarding the scene units you can find more info here - https://docs.chaos.com/display/PHX4MAX/Liquid+Grid

[JuhaHo]

Thanks,

I mean, if I have millimeters as my working units, do I need to tweak the default shader unit values?

I use separate simulation geometry since the CAD-geometry is not watertight.

[georgi.zhekov]

Depends on the scene and and your setup. Sometimes you might need to tweak it and sometimes it will work with the default values.

[JuhaHo]

I still don't get it. Creating decent boat wake renderings is much more difficult with VRay 6 than it was with VRay 5. Do You have noticed any issues?

E: I mean are the default values being defined by using scene having different units set up? And if so do I need to manually change the default values according millimeters?

[georgi.zhekov]

Are you using the same scene and just changing the V-Ray version from 5 to 6?

There shouldn't be any issues when doing so.

[JuhaHo]

The only difference here is the sunlight with clouds that didn't exist in VRay 5. I started with the speedboat template as many times before. I just can't get the boat wake foam look as nice as it was with VRay 5. I'm here to discuss how I should change Phoenix settings. I have 9 meter (9 000 millimeter) boat running 35 knots. The simulation has similar setup than earlier, but the rendering results are quite different.

[georgi.zhekov]

If you have both scenes, the old and the new one we can take a look and suggest how to optimize it.