The Motion Vector ROP can be used to generate a texture for time warping texture sheets in your game engine. It requires a vel field for volumes or the point attribute v to create the texture space vectors. Attempting to create motion vectors for low density volumes can sometimes create innacurate results. Using an external package to generate optical flow maps is recommended in that case.
Start and End frame of the render sequence.
Node to export. Make sure you select the object level node.
Path to render sequence.
Motion Vector Map
Path to motion vector image.
Images per Line
Number of images, side-by-side, on the horizontal axis.
Final resolution of the motion vector image. This is not the same as the resolution for each frame in the render sequence.
No. Of Frames
Total number of frames from start to finish
How the images are layed out in the texture sheet.
Resolution per Frame
The resolution for each frame based on the atlas resolution and images per line.
The exported image has normalised values. Sometimes the movement per pixel is greater than 1. This multiplier captures that difference. Copy and paste this value into the raw multiplier input of the material function in UE4.
Material Function Code
Copy and paste this code into a material function in UE4.