Problems with Flicker and Shadow Popping

[cyphyr]

VIMO LINK
Well here's an old thorny one.
Firstly, it's only a second long and its only a test!
I have disabled GI (0,0 and disabled the environment light) and added Oshyan's Fill Lights. I have also set in the Advanced Rrender tab: Ray detail region > Detail in camera = 1. I am still getting very obvious flicker and shadow popping. Look at the shadow "popping" across the left hand hill and the flicker in the low fog on the right hand side. There are plenty of other examples. So what other solutions are there? I've tried using GI again but with a much higher Blur Radius but that creates odd artefacts unless I have the detail setting very high. Maybe that is the only solution. Be nice to have it confirmed that you simply cant animate a scene with clouds in it unless you use very high render settings.

Richard

[cyphyr]

Trying again with the Cloud Qualities set to 1 and "Conservative acceleration".
Also what are the reccomented settings for "Ray detail region"?
cheers
Richard

[Tangled-Universe]

If you want to exclude cloud cache problems you might consider disabling it entirely, since it often causes problems like pixelated results for example.
You might even try to disable clouds entirely and then see if it still occurs. But disabling the cache would be the first thing to try, for me then.

It's hard to say what's best to use for ray detail region. Since you also see popping in the middle of the frame, and not only on the sides, I wonder if it will really help.
However, it never hurts
I guess you already know that a setting of 1 corresponds to 1 frustum outside the camera-frustum to be calculated.
So for a 500x500 image a ray detail region of 1 corresponds internally to a 1500x1500 image (3x500 horizontally and 3x500 vertically, with the camera-frustum in the middle).

I presume you also have detail blending enabled and set to 1?
Do you use small scale displacements? I'd go for as low octaves as possible.

[Oshyan]

There appear to be several sources of flicker here. First, definitely turn off the cloud layer acceleration cache entirely for both layers. I would guess that will take care of the flickering in the clouds to the right. It may well not take care of the larger shadow issues on the terrain on the left. I'd try increasing Ray Detail to 2, if only as a test. You'll also definitely want to set Detail Blending to 1. Finally, soft shadows may be playing a role in the noise flicker, but are probably not involved in the rest.

See if any of that helps.

- Oshyan

[cyphyr]

Thanks guys
Yes, turning the Acceleration Cache to "None (Highest detail)" has fixed the flicker in the clouds.
The shadow popping in the terrain is still an issue, took it* form 0 to 0.5 to 1 and the shadow popping is still there. I'll try upping to 2 but I'm thinking this won't help that much as the source of the shadow is pretty much behind the camera making it near impossible to create a camera fostrum that surrounds the camera. (please correct me if I'm wrong on this one). I'd forgotten to up the Detail Blending, I'll give it a try.
Small scale displacements; I've taken my octaves down as far as I think I can get away with in both cloud, terrain and textures.
Soft shadows; hmm well I'd rather not disable them, the scene just dont look right without them, it is sunset after all
Thanks again
Richard
*Ray Detail Region

[cyphyr]

Ok I tried with the detail blending set to 1 and the Ray Detail Region set to 2, with the acceleration cache OFF and now each frame is taking 1hour 45min from a previous 15min.
Thats 7 times longer!! I cant use that, life is too short
Animating sunset scenes seem to be highly problematic due to the interaction of the sun, cloud and terrain at low angles, way too much calculation going on.

Thought: Would a non procedural terrain still have these problems (shadow popping) given that the terrain would not have to be calculated?

I've attached the fle if anyone wants a play.

Richard

[Oshyan]

I believe heightfield (non-procedural) terrains are still handled as displacement so they might be subject to the same popping issues, though you may be right that LoD is not performed on the base terrain features since they are finite. I'm not sure, worth a test tough.

While I completely agree the render time is unmanageable, were you able to determine if it at least fixed the problem?

- Oshyan

[cyphyr]

I'm rendering at home over night so we'll see in the morning
Do you know if these shadow popping issues are liable to occur at the same time frame each time?
I've lowered the settings as much as I feel I can to still get a decent image.  Up to 20 min per frame I think is usable for animations.
Cheers

Richard

[Oshyan]

Not sure if they would occur the same frame. There are some elements of TG2 scenes that do vary semi-randomly between renders (of the same PoV/frame), but in general these things should be minimized with appropriate quality levels.

- Oshyan

[cyphyr]

Ok so the atmospheric flicker is no longer there but I am still getting shadow poping on the terrain. (13 frames in 25 hours).
The thing is its a simple scene, two cloud layers, one of them a "merge" between two Cloud Fractals, one just plain vanila.
The quality is set to 1 (samples 128) and the low mist is quality 2 (samples 49). The terrain is simple as well, two Power fractals and a Strata shader so I'm at a loss as to what there is left that I can optemise; a single frame I can get rendered in down to 15 min and it looks perfectly fine but to animate it I need to bring the setting up sooo high it just becomes unfeasable.

Richard

[Kadri]

I use the free version thus i can not try it ; does the Planet Displacement Tolerance setting have any effect on this kind of problems?
More precise ground or LOD outside the camera and such ?

[Oshyan]

Good question Kadri. From my understanding it should not matter, unless Displacement Tolerance has fall-off out of frame (which it might). It's worth trying for sure.

Richard, I'll check out your scene file again and see if I can find settings that fix this. Do you know the specific frame numbers where the issue is most apparent?

- Oshyan

[cyphyr]

Hi Oshyan
Thanks for looking into this.
It seems to be a reccuring problem with low sun angles (sunsets), especially with the sun behind the camera.
I've tried a number of alternative setups, detail blending and Ray Detail both set to 0.5 seem to be a "seme" reasonable compromise with rrender times commiong in at about 30 -45 min a frame. Not as good as 20 min and cirtainly not as bad as 105min! Disabling the cloud cache dose not seem to add "that" much to the render time.
My internet connection is restricted at the moment (till I can find £££ to pay the man) so I'll be a little slower to respond.
Thanks for looking into this
Richard