Setting to start with on an exterior animation sequence with lots of tiny details

[king_max]

I need to render a 2k frames sequence of the exterior of 7 villas. I'd like some advice from someone that has experience on rendering exteriors shots with lots of small details (grass, trees, bushes) regarding the appropriate GI settings, shadow subdivisions, AA settings etc. I've attached an image from a shot. The main problem is the flickering on the bushes in front of the camera. The scene is lit only by the vray sun/sky. I've tried different settings, but the flickering persist. I cant figure out if it's an AA, GI or mats reflection subdiv. related problem. I've begun with DMC 2-6 - noise thrs. 0,003, LC 2000 (walkthrough), world 2 cm, IRR - medium animation preset with subdiv 80/25, noise thrs. 0,005, all mats subdiv. ranging from 16-24. With these settings the GI solution seems pretty decent but the flickering was noticeable. I've tried another variant by lowering the DMC AA thrs. to 0,002, pumping all the mats to 32 subdiv and using the HIGH IRR preset with 100/30 subdiv. Apart from the doubled rendering times, the scene is a bit cleaner but those bushes are still flickering. I just don't know how to "optimize" the scenes to get a decent flickerless result. Seeing Roman's video I just wandered how does one get such a clean result thus keeping the render times acceptable (figured I can accept 30-45 mins per frame on a dual xeon 5520). Is there a way to bring those rendertimes down? All the sequences are rendered in HDTV 720p resolution.

[joconnell]

One thing worth trying is to turn on render elements for the main elements - specular, reflections, shadows, lighting and global illumination. You can look at each of the parts of the render and see is there a particular section causing the noise - it might be a light or a material. Alex uses the quadratic filter for his animations too which is slightly soft - this will help with some of the noise right away. Definitely render a velocity pass too as a small amount of motion blur can also smooth over noise if it's the small, grain type noise.

[king_max]

I was hoping for a quick solution based on peoples past experience with the issue. I'm already using the quadratic filter, and yes, I'm having issues with grain type noise. I just wanted to know what are you guys using on scenes with 3D grass or bushes with tiny leaves. There's just not enough time for me to test out all the passes and find the cause of the "problem". I always had this issue when rendering scenes with small details. My guess is that I'm using a too low AA settings, but I might be wrong. I can try with AA DMC 1-50 with a really low threshold but my guess is that the render times will go skyhigh. I'll post a link to the sequence so you can judge for yourselves.

[leo.surrealismo]

hello,
these are the settings I use. Give it a try

[king_max]

Thx. I'll give it a try tomorrow. Just a few questions. Doesn't using "sreen" for LC produce artifacts in an animation? I can also see that u set the global subdiv. multiplier to 8. I'm assuming all your lights/mats have the subdivison set to 4?

[leo.surrealismo]

in theory it does, but setting it on screen mode makes the calc faster and generates a clean result (in my experience).
My materials subdivions range from 4 to 8 max.

[joconnell]

If you're doing a really large flythrough where the camera travels long distances, then you really have to use world space. Lets pretend that you have an animation where the camera zooms in to a wall far away in the distance. If on frame one, you have a sample that hits the wall really far away in the distance, it will look the same size as a light cache sample close to camera. The problem is that when the camera starts moving towards the sample really far away in the distance, that sample is going to start getting bigger and bigger as it gets closer. You might end up with a light cache sample that's the same size as the wall! Screen space makes sure that all of the light cache samples are the same size in terms of pixels in your final render - it's perfect for stills or cameras that don't move a huge amount. Your light cache samples are nice and detailed for the bits up close, and the parts farther away from camera get less details which you can't see anyway. If you use world space, a light cache sample size is like a sphere in 3d - so a sample really far away will look tiny compared to a sample close to camera. Again if we use our example of a wall up close and a wall really far away, the samples by our close wall will be normal size, and the samples at the far away wall will be tiny, but when the camera travels over to the far away wall, the sample will be normal size and you'll get a much more even lighting solution throughout the scene.

Quick rule - Camera doesn't move much, use screen space. Camera moves a huge amount, use world space.

[king_max]

I understand the theory behind LC samples. I just never used screen space for animations in fear of possible glitches. Well, In this particular project I won't have any camera zoom ins/outs. From what Vlado stated somewhere in this forum, the LC complexity doesn't affect the render times at all. I've put to test lxgrunger's settings and for now it renders faster and cleaner than with my settings. (Thanks a lot!) Only thing I've changed is the LC size. (set to world instead of space). Anyway, in an exterior scene like this the LC solution (sreen vs. space) really doesn't affect the render quality and shouldn't affect the grainy noise type.

[leo.surrealismo]

I'm glad the settings worked.
I'm going to start using world instead of space; but how about the sample size? would it be good to have 0,01 m?

[king_max]

Depends on the scene. In my case I figured out a 2cm size would suffice. Obviously, it depends on the scene scale and max units settings. If you're working in inches, then 0.8 - 1.0 should be a good start.

[3DMK]

It's more than likely that your Flickering is caused by Anti-Aliasing & the very small leaves on the grass & shrubs.
This is the main cause of flickering in trees & plants in animations & can only really be overcome by using either DOF or MBlur [or both] or rendering at a massive resolution [like 5K] & then resizing back to 720p.
Unfortunately there is no quick fix for this issue other than to prevent having camera paths that see everything [foreground, mid & background in the same shot]

Hope this helps

[king_max]

I supposed so. So, how does "Icube Visualization" (the Russian studio) or other studios render those aerial views with tons of trees? They render a "vegetation" pass in 5k?!? Those sequences are flawless in terms of noise/flickering. I think they're using vray, though I could be mistaken.

[johnszot]

king_max: now THAT is a question i'd like to see the answer to....

[Magnum_design]

There is a thread on that in the multiscatter forum. I think brute force/none is the answer.

[glorybound]

They do say if you are using Light Cache don't bother asking about crashing scenes. With Multiscatter you have to use brute force