Animation flickering

[fAEkE]

Soo, after a week of testing I'm now pretty confident with the GI solution when rendering an animation in Vray, but I have another issue. I'm rendering a car interior fly-through with some moving objects, and I'm using IM/LC for the GI. The GI does not flicker, so thats not a problem anymore, but I have some AA problems instead. The major problem is that the bumbpmap on the seats are flickering very much.. looks like as if the bump moves (crawls) fast over the seat while the camera is slowly panning past it.

The arealights in the scene are set to 16 subdivs, materials to 12 subdivs, and my adaptive DMC sampler is set to 1/10, 0.003 threshold with time independent Unchecked.

So, does this "crawling" of the bump occur because of low subdivs in the material? Or is it because LC can't handle the bump very well? I bet most of you have encountered similar problems before.

[fAEkE]

Sorted it out, was because of 2 low subdivs. Unfortunately rendering animations is slow when you need good quality frames, and there are no other options..

[joconnell]

Yeah, small patterns like bumps or cloth is tough, especially with gentle camera moves. It's often worth adding in the diffuse filter element or an extra tex with your bump map so you can see if it's your texture that's crawling across lines of pixels (nasty broadcast / res issue that only gets solved with softening / sampling / motion blur) or a shading issue.

[fAEkE]

ye, been trying to refine my render settings all day to get rid of this crawling and at the same time have decent render times. My conlusion is that it's impossible. It just takes forever to render a clean frame

[joconnell]

It's a very tough one alright - if the crawling is being caused by small details in a texture or a really fine bump then you need to use high anti aliasing to smooth it out. The only problem with that is if you're using a lot of glossy materials, the high aa will turn down the samples of your glossy material and make them noisy. It's really difficult to figure out a full approach of how to optimize scenes for every situation in vray - it'd be high on the list of things to do for me if I ever got any free time

[Morbid Angel]

i must point out that you have to be careful with fine bump maps and samplers. If you set the bitmap filtering too low, which produces more crisp texture results, it will impact your sampler in a negative way. The crawling you may experience is a moire effect or worse a combination of that with bad sampling. Typically setting filtering to 1.0 should fix any fine texture flickering, and will speed up rendering of those areas, because the sampler will have to compensate less.

[fAEkE]

I think the bitmap has 0.5 blur, and 0.68 glossy. Very fine bump. So it's a tough one ye Rendertime per frame was about 30 mins in 720p with the flickering result. When I testrendered and finally came up with a noisefree result, the rendertime was at 3-4 hours per frame way too much when you only have 8 PCs to render with. I'll try 1.0 blur tomorrow.

joconnell, can you explain this please: "The only problem with that is if you're using a lot of glossy materials, the high aa will turn down the samples of your glossy material and make them noisy"

[joconnell]

The apparent rule with Vray and it's unified sampling is that if it's using a lot of samples for anti aliasing, it automatically turns down material and lighting samples which can sometimes harm the end look of a render - it might be more efficient to use material samples to clean up parts of an image but vray wrongfully tries to do the cleaning up with the high number of image samples it's gotten from your aa settings. I've got to check with vlado if there's an order of priority of the samples - like for example which is most important in terms of deciding how many samples are used in the end, your anti aliaser or the dmc?

[fAEkE]

Rly? I thought vray used the same min/max number of primary rays for all kinds of secondary rays. I use dmc ye