3D rendered shop front with GI

At YellowDog we do a lot of 3D rendering. One of the hardest things to get right, especially when you’re using many different machines to do the rendering of an animation, is how do you ensure every frame has exactly the same lighting when using Global Illumination, or GI. Given the complex mathematics and sampling used by render engines to calculate the lighting, it’s quite common for flickering and other artefacts to appear in the render.

For scenes where you have moving objects, and are being rendered with V-Ray, the best solution we’ve found is to use time-interpolated irradiance maps. These work by blending samples from several irradiance maps which helps ensure there is no flickering or differences between the frames. It’s also a lot faster than using brute force rendering.

There are two steps needed to render the animation:

  1. Create the irradiance maps for each frame of the animation.
  2. Render the final animation.

Once you’ve opened your scene and gone, the V-Ray settings for the first step are:

SettingValueReason
GIOnEnables Global Illumination for the scene
Primary Bounces EngineIrradiance Maps
Secondary Bounces EngineLight Cache
Irradiance Map PresetMedium animation
IM Subdivs50
Interp samples20The number of GI samples from each irradiance map used to interpolate the GI at any point
Use Camera PathCheckedHelps to reduce flickering when the camera moves
ModeAnimation (prepass)
SaveChoose a directory to store the irradiance map
Don’t deleteChecked
AutosaveChecked and Choose a directory to store the irradiance maps
Light Cache Subdivs1200
Sample size0.15
World ScaleCheckedThis is the right mode for animations where the camera is moving.
Use Light Cache for Glossy RaysUncheckedIf you check this, you will need to keep Light Cache as your Secondary Engine in Single Frame mode for step 2
Use Camera PathCheckedHelps to reduce flickering when the camera moves
ModeSingle Frame
Animation start framePlayback start -2Ensures all the irradiance maps needed for every frame are calculated. If you start from the beginning of the playback, the first few frames will be noisy.
Animation end framePlayback end +2Ensures all the irradiance maps needed for every frame are calculated. If you finish at the end of the playback, the last few frames will be noisy.

Now render the whole animation.

You should see an individual irradiance map for each frame appear in the directory you specified.

Once this is done, you’re now ready to render the final animation. The settings for this are:

SettingValueReason
GIOnEnables Global Illumination for the scene
Primary Bounces EngineIrradiance Maps
Secondary Bounces EngineNoneThe light cache information has already been generated and stored in the first step
Irradiance Map PresetMedium animation
IM Subdivs50
Interp samples5Decreased as several irradiance maps are being used for rendering. If this doesn’t look right, you can increase it. You may have to go to 10-12 for interior animations although this increases render time.
Interp frames2How many irradiance maps are used for rendering one frame of animation.
Use Camera PathCheckedDoesn’t have any effect any more.
ModeAnimation (rendering)
SaveChoose a directory to store the irradiance map
Don’t deleteChecked
AutosaveChecked and Choose a directory to store the irradiance maps
Animation start framePlayback start
Animation end framePlayback end

And press render.

We’ve found this method produces great results every time.

Happy rendering!

 

…. (Update 2018)

Two years on since this was published, this continues to be one of YellowDog’s most popular 3D tips and tutorials.

See the 2018 update below.

Comments

arnel says:

Just a quick question on the animation rendering mode, i think instead of save, it should be “load the saved IR” that was previously computed from the pre-pass ? not sure. would like to know your though. thanks anyway this is pretty coo.

Damone says:

Tried these setting and was able to render IM. But NOT the final render. Using Vray 3.40.01

lukas says:

will you update this for vray 3.6?

Jack Davies says:

Hey Lukas – great suggestion. I’m part of the team at YellowDog and I actually had a chat with the team behind our 3D tips last week. We’re going to update ‘flicker free animation’ tips very soon as this post is so popular – even 2 years after we made it. and I’ll request we make it applicable for 3.6 🙂

Also – you might find something of use in these tips for flicker free…
GI for V-ray and Irradiance Maps for V-ray

https://www.youtube.com/watch?v=38JDlCgjtyY

https://www.youtube.com/watch?v=AatNDHQV98c

henry yamin says:

Please update the to 3.6 version 🙁

Jack at YellowDog says:

Totally agree Henry. I’m part of the team at YellowDog will be issuing an update very soon.
In the meantime, the below videos are also good for flicker free V-ray tutorials:
GI for V-ray and Irradiance Maps for V-ray

https://www.youtube.com/watch?v=38JDlCgjtyY

https://www.youtube.com/watch?v=AatNDHQV98c

Jack Davies says:

Here’s the update you were after Henry – Just published this week.

https://yellowdog.co/2018/04/17/yellowdog-3d-tips-45-render-flicker-free-v-ray-animation/

Leave a Reply

Your email address will not be published. Required fields are marked *