Displacement on Glass, long rendertimes

[fAEkE]

I'm making a bottle that has text and other details on it that needs to be done using displacement, the problem is that the rendertime skyrockets when enabling the vraydisplacement modifier. The details are small and only covers a small part of the bottle, but I guess vray calculates refracting rays from the displaced part all over the place and that is the problem. Is there any way to speed this up? It's supposed to be an animation in the end and with rendertimes of 60 mins with testsettings I will never be able to get this out with displacement.

Using 2D displacement btw.

[Dariusz Makowski (Dadal)]

Yup u need to tune up displacement settings. U probably subdibividing the geometry a lot more than u have too. Try decreasing the displacement subdivision and tune it out. I'm using displacement to turbosmooth my models and my renders render as fast as without displacement.

[fAEkE]

Hmm, you are right that I have subdivided the geometry alot on this bottle, so the displacement itself should not need to subdivide it at all almost. But 2D displacement does not use subdivisions as 3D does, how do I control it?

[Dariusz Makowski (Dadal)]

No idea - I only use 3d/subdivision mode - maybe apply grey material + displacement and see if it will still render long... or just use bump map...

[fAEkE]

Bump is not an option. But I skipped turbosmooth and it rendered quite quick. So I'll just have to MSsmooth some parts of the modell where I need to and get rid of the turbosmooth.

Thanks

[Dariusz Makowski (Dadal)]

Weird - try using displacement in 3d/subdivision mode...

[fAEkE]

Tried it, 3d displacement always takes 103139010490 years for me to render. Barely even worth trying.

[simmsimaging]

3D displacement shouldn't be that bad IMO. I'm guessing you need to tweak the values. I've done quite a bit of displaced glass and water droplets etc and the render times are not out of control (but then again I'm doing very high res stills as a rule so maybe my view is different )

Anyway, try increasing the edge length (maybe a lot at first) and see if you can strike a better balance of detail and time. I would be inclined to leave the turbosmooth on under the displacement modifier too.

[fAEkE]

Im used to A2 renders so I think we have the same view on rendertimes, but its probably me who does not know enough about the settings. What subdiv and edge length value do you recommend starting with? U got any default values that you usually use?

[simmsimaging]

Default values would depend on scene scale and scene units, and the maps being used - I don't really have one unfortunately

I tend to work real-world for the sake of keeping things more intuitive. That way you can set the edge-length (not using view dependent) to something appropriate to the shape as a starting point. For type on a bottle I would try something like 2-3mm and see how it goes. It should be kinda chunky, but fast. You can then shorten it up till you get the right balance for your shot. Definitely faster to test with a solid (non-refractive) material till you figure it out.

I tend to leave the subdivision setting at default (which I think is 256) and just control the quality/time with edge length.

If that doesn't work for you I'll try and dig up an appropriate scene and see exactly what I used.
/b

[fAEkE]

Thanks. 2D is working great for me now so I will stick to that, but I'll keep this in mind until the next time and try 3D again. Maybe I will make a test tomorrow tho, seems like some CAD is a bit late so I wont have anything to do the first couple of hours anyway.