Animation settings question when using Primary BF and Secondary LC

[tricky]

I am doing a bit of 'out-of-hours' experimental animation to further my skills. Normally, we move only our camera around an interior space, so we use flythrough LC and IRmap settings, but I am trying to animate objects and lights within the scene to see just what is possible.

An interior scene I am looking at has a curtain gently blowing in the wind in front of a window. The scene is lit only by a HDR. The curtain has a vray2sided material applied to it. I am using BR as the primary engine (64 subdivs) and LC (1250 subdivs) as the secondary engine I am getting some flickering light occurring near the curtain on the wall. I wondered what setting I should be looking at in order to improve the results. Average render time is around 50 minutes at the moment for a 1280px frame.

[tricky]

In actual fact, even when I look at another scene where only the camera moves, I am seeing flickering in the renders from frame to frame. I guess this is to be expected as a new GI solution is calculated for every frame, so therefore some flickering is inevitable. What is the best way to render a scene where I want to see all the detail/subtlety that BF can give you, but is also good for static scenes and scenes with changing light or moving objects?

[tricky]

I wonder if I could send my scene and some of the renders to Chaosgroup for them to suggest ways to improve my scene? How should I go about doing this?

[tashko.zashev]

Hi,

You could send us the problematic scene and few render frames in order to give you some advices or recommendations.

Before to doing this please try to turn ON "Use Camera path" option for the Light cache calculations. It should reduce the flickering in your case.
Also you can check the render passes to be sure that the flickering occurs only in the GI part, because the flickering could be from the reflections .

[tricky]

Hi,

You could send us the problematic scene and few render frames in order to give you some advices or recommendations.

Before to doing this please try to turn ON "Use Camera path" option for the Light cache calculations. It should reduce the flickering in your case.
Also you can check the render passes to be sure that the flickering occurs only in the GI part, because the flickering could be from the reflections .

Many thanks. I will check and set another render going tonight.

[tricky]

Before to doing this please try to turn ON "Use Camera path" option for the Light cache calculations. It should reduce the flickering in your case.

Should I therefore 'precalc' my lightcache for the entire sequence in 'flythrough' mode with 'Use Camera Path' enabled? (I do have animated curtains in front of the window which will subtly affect the GI from frame to frame). Then for rendering the frames, I set BF as my primary engine and LC for secondary (using the saved LC solution)?

[tashko.zashev]

Hi,

I assume that you have moving objects in the scene (the curtains for an example) so in this case precalculating the Light cache in Flytrough mode is not the best approach. It is better to calculate the LC for every frame and keep "Use Camera Path" option ON.
It is just one GI animation approach that could be suitable for your case.

You might consider to force your moving objects to use Brute force engine only by un-checking "Use Irradiance map" on its material.

However, feel free to send us part or the entire scene to the support and we will try to add more solutions.
Thank you.

[tricky]

However, feel free to send us part or the entire scene to the support and we will try to add more solutions.
Thank you.

Thanks Tashko - could you confirm an email address to send the scene to?

[tashko.zashev]

Thanks Tashko - could you confirm an email address to send the scene to?

You could use the support mail: support@chaosgroup.com
Just don't forget to add this thread as a note. Thanks

[tricky]

You might consider to force your moving objects to use Brute force engine only by un-checking "Use Irradiance map" on its material.

I've not tried this approach before. Is it JUST the moving objects whose material I should change, or materials that are affected by the moving objects also? For instance, in my scene, my curtains are reflected quite strongly in a timber floor.



Also, using this approach, I presume I still use LC with 'use camera path' ticked for secondary engine, and use IRmap for primary engine - if so, should I also have 'use camera path' checked for the Irmap? Or, should I be pre-calculating the IRmap and LC when using this approach?

So many questions....animation has always been a can of worms.

[tashko.zashev]

You could change it for the moving object only (its material or materials if you use Blend or any other complicated shaders)
If you have flickering over the curtains it will be visible in their reflections as well.

[tricky]

You could change it for the moving object only (its material or materials if you use Blend or any other complicated shaders)
If you have flickering over the curtains it will be visible in their reflections as well.

I'm just zipping up the project now and I will upload it to our server and email you a link. Your thoughts on setup would be appreciated.

[tashko.zashev]

I'm just zipping up the project now and I will upload it to our server and email you a link. Your thoughts on setup would be appreciated.

Thank you, we will check the ticket.