Flickering grass/trees outdoor animation

[skare]

Hey guys, i have large outdoor scene with poly grass (autograss), poly trees (via VrayProxy/Multiscatter) and castle as main object. Terrain is approx. 1000x1000m and slowly movig VrayPhysical camera 300m from castle. There is VraySun light source. Grass and all trees are flickering so much.
My vray settings :
AA: Adaptive DMC, Quadratic filter: Min2,Max3
DMC sampler: noise thresh:0,003 , Min samples:12, Time independent: check
GI: Irr map: Min:-3, Max:-1, HSsub:50, Inter.Samples:20, Nrm. thresh:0,3, Dist. thresh:0,15, Use camera path: check, Interpolation type: Least squares, Sample lookup:Overlapping
LC: Subdiv:1000, Sample size :0,005m World scale, Fly through mode,

Any ideas how to reduce/remove flickering from grass and trees ?
Thx

[Morbid Angel]

min samples 12? thats overkill. The flickering is most likely due to bad gi settings. For the outdoor scene you don't need light cache. What I would suggest is to do a simple render of 10 frames with just brute force and dmc of 3/8 to see if that helps the flickering, if it does then you need to address your irradience map settings. If it does not, then gi is not at fault and something else is going on. You should never have to go min 12.

[Neilg]

dmc at 2,3 is way too low too. I tend to render anywhere from 1,6 to 1,8. Your noise threshold is incredibly low too, try .008

[super gnu]

well i dont see any mention there of your imap settings ( single frame/ multiframe incremental etc)

if youre using single frame, then youll almost certainly get flickering without massively high settings. im assuming lighting and geometry are static, so in this case, use multiframe incremental, and precalculate your imap every 10 - 30th frame, and use the saved file. this will give you a static gi solution, and remove any gi flickering.


as cubiclegangster said, dmc2/3 is -way- too low for your Antialiasing. with fine details (and trees and grass certainly have fine details) you need very high aa.

id actually say you need much higher settings than suggested above. for exterior animation with trees i usually end up using a min of 2-4 and a max of anywhere up to 20. all depends how much shimmering you can bear, and how long you need your renders to take.
once you have calculated your imap, id generally crank up the aa nice and high, and control the look using the noise threshold. raise it to 0.01 ( default) then bring it gradually down until it either looks good, or takes too long


tbh i also always use lightcache. as long as you have it in flythrough mode and use it to calculate the multiframe imap, it wont increase flickering. wether its necessary or not for exterior lighting depends on scene and the look you want.

[trick]

This question has been raised so many times and there still is no "sticky" answer for it !!!

There are several kinds of flickering in animations of which the most important one is the small details one !!!

The thing with AA is that when you set a min value of 1 and a detail is so small that it isn't even visible when rendering, you can max sample as much as you want, it will never be taken into the equation !!!!
One frame ahead it suddenly IS visible and then it IS taken into the equation, which results in very different results .... and therefore: FLICKERING !!!

To prevent that, with a min value of 2 there is not ONLY a bigger possiblity that the detail becomes visible, but even when it is NOT visible the pixel(read color) values are averaged out of 4 (2x2) pixels (read zooming in on ONE REAL pixel), making the difference between the previous and/or next pixel (in TIME) less obvious, whether the small detail is visible or not !!!

A min 3 value is mostly overkill, but with HD animations shown on very sharp (LED) HD monitors I sometimes still experience too much flicker in the details.

Flickering from GI, Glossies or Texture Sampling is another story, but since this was only about grass and leaves, the problem is most certainly SMALL DETAILS!!

There is an easy way to check: just do not use GI (only ambient, no other lights), no textures and no glossies, and render a small fragment !!!

[skare]

Thanks guys for all ideas, ill try all of them, generaly all of U are according that main issue is in AA and too low Max value. Ill keep U informed about my progess

And about animation, scene is static(without moving objects), camera is fly through. Is in my case necessary to calculate multiframe incremental Irr map or its posible to calc. from few(for example angels and then merge it. Bcs calculation takes a lot

[super gnu]

well if you use multiframe incremental correctly (i.e. calculate every nth frame) then this is basically the same as doing "a few angles" since you will need to cover all the geometry that is visible in your scene in either case. if you scroll through your camera path, simply check what is the minimum number of frames you can calculate to cover all the visible geometry with lighting.... as long as each visible surface is seen in at least one of the lighting calculation frames, you will be fine.

however id always advise to use multiframe incremental rather than doing single calculations and merging them, as it will be much faster.

this is because with multiframe incremental, it will not bother to calculate any lighting for surfaces that were done in a previous calc. if you do seperate calcs and merge them, you will lose this efficiency. also, i believe, the imapviewer does a pretty bad job of merging imap solutions. you will end up with a much larger imap file with many duplicate samples in.

[cecofuli]

I've the same "problem" in this day for an animation in PAL DV res.
A lot of tree, grass etc... as usual in pour last project. I want to share my setting:
(*) IM + LC is good. Ok, we loose some details, like thin bump, or in the dark area. You know well this. With BF+LC or BF+BF we have more detail, but rendering time will be very high!
My goal was to have a nice rendering time, without flickering, good quality (not super!) and, obviously, without splotches.
(*) So I calculate the IM with High animation preset with 640x360 resolution with use camera path technique. 100 20 as a subdivs
(*) LC: Fly, 3000, 30cm, World, Use camera path as well. Usually the camera path was 200 or 400 frame.
(*) Now the "problem". The AA... I use DMC 2-12 with quadratic. Less, we can have flickering, for example, with 1 and 8.
(*) DMC sampler default.
(*) Turn off all the VRay2Side Material and physically glossy for every leaf shader. This can speed up a lot the rendeirng (from 1 hours to 40-45 per frame with esacore I7)
It's a lot for 4000 frame! I know, we don't have a translucency foliage. But my client don't see the difference. If you have a good hardware, you can use SSS and glossy.
(*) Change from Opacity ON (with filter on NONE) or OFF for the foliage, don't change nothing in our test. Same rendering time.

That's all

[super gnu]

i always wonder why people calculate the imap at a lower resolution than the final sequence. this is -identical- to doing it at the original resolution, but with a higher min and max setting..

id also suggest that a sample size of 30cm world scale for the lightcache when dealing with a several km landscape will be vastly too heavy..? i spend 75% of my time doing masterplan animations, and to be honest the default settings for lightcache (apart from maybe increasing the subdivs due to using flythrough mode) should be absolutely fine for an exterior. its only used as a basis for the imap samples after all. if you need more detail youre much better off increasing the max rate in the imap.

[cecofuli]

Because: 640x480 with high preset (3 0) is : Min 640/2/2/2 = 80px Max 640
Pal DV is 1024x576 with high preset (3 0) is : Min 1024/2/2/2/ = 64px Max 1024/2 = 512

So (80 and 640) vs (64 512)

Ok, not so big difference. I could use 1024x576 with -4 and -1 ^__^

About LC you are right. But my scene is a little house and yes, with world is ok. With Km land I think is better Screen.

[skare]

Thanks cecofuli for sharing your setting, ill try it, bcs with my settings and incresed AA setting i still have flickering in grass and trees, and deadline is squeezing my balls Btw calculating Irr map DR(4x Intel i7) 640x360 takeing quite long. I suppose U was talking about Multiframe incremental Irr map calculation, at least every 30 frames.

[cecofuli]

IM is very fast.
For example, I've a short camera movement. Every 400 frame I change view. So, I "cut" my 3ds max timeline from the start to finish ( ex: from frame 400 to 800), I use IM as a single frame with camera path on. LC as a fly-throught with camera path OM.

[Neilg]

If you're strapped for time with IRmaps, hide all the glass/water and turn reflection/refraction totally off. It'll go so much faster.

[skare]

Now im calculating cecofulis 640x360 Irr map DR 4x i7 and 1 frame shows it wil ltakes 20h, and reflections,refractions are OFF. Its old low settings image. Is it good time for U guys?

[Neilg]

Not even slightly, something is massively wrong. Do you have opacity mapped leaves on those trees, and have you turned filtering off? How much displacement do you have in the scene?