Denoising animations in V-Ray for Maya

Software:
Maya 2018 | V-Ray 3.6

Animated sequences require ‘Temporal Denoising’ in order to achieve a flicker-less result.
‘Temporal Denoising’ means that in addition to taking into account neighboring pixel data, the denoising process also takes into account pixel data from adjacent frames in the animation.
For that reason, the V-Ray Denoiser render Element can’t simply be used during the render process like we can use it when rendering still images,
And the animation sequence is denoised after it has been rendered, and stored with extra data needed for the V-Ray Denoiser to work.

Update:
In V-Ray Next the vdenoise.exe tool has a GUI that allows loading sequences easily.

In versions of V-Ray prior to V-Ray Next the vdenoise tool has to be operated through command line with the following easy steps:

This is a very useful article on the subject from Dabarti studio:
http://dabarti.com/vfx/using-v-ray-denoiser-tool-vdenoise-exe-with-send-to-scripts/

General sequence denoising setup that has to be done just once:

1) Create a command line denoising script batch file, and store it in the Windows ‘Send to’ folder:
Write the following script to a new text file.
* this script is from an article by Tomasz Wyszołmirski – Dabarti Studio.

@echo off
set input=%1
set denoiser_input=%input:~0,-8%????.exr
"C:\Program Files\Chaos Group\V-Ray\Maya 2018 for x64\bin\vdenoise.exe" -inputFile="%denoiser_input%" -useGPU=2 -display=0
pause

Save the file named ‘Denoise Sequence.bat’ in the Windows Send to folder.
* to find the Windows Send to folder quickly open the Windows ‘run’ utility and type: shell:sendto.

Render setup for denoising:

2) In your Maya scene, In the Render Settings window, In Render Elements tab, add a Denoiser Render Element.

3) Select the vrayRE_Denoiser Render Element,
And in the Attribute Editor, under Exta V-Ray Attributes set ‘Mode’ to ‘Only Generate Render Elements’.

4) In Render Settings > Common > Image File Output:
Choose exr (multichannel)

5) Render the Animation.

Denoising the animation:

Right click the first frame of the rendered sequence,
And choose Send to > Denoise Sequence.bat

Related post:
Rendering an animation with Maya and V-Ray