Computes horizontal and vertical optical flow into two separate optical flow maps. This module is intended for use as a pre-processor, that is, the images sent out may be further processed by the host computer.

The optical flow image output is twice taller than the camera input image:

• On top is the horizontal motion map
  • darker shades of gray for things moving rightward from the viewpoint of the camera,
  • lighter shades for things that move leftward,
  • mid-grey level for no motion
• below it is the vertical motion map
  • dark for things moving downward,
  • bright for upward,
  • mid-grey for no vertical motion.

You should be able to run this algorithm at 100 frames/s with 176x144 video camera resolution.

This module has parameters to tune the algorithm. Interested users are referred to the original paper and implementation for how to set these:

"Fast Optical Flow using Dense Inverse Search" by Till Kroeger, Radu Timofte, Dengxin Dai and Luc Van Gool, Proc ECCV, 2016.

Also see here: http://www.vision.ee.ethz.ch/~kroegert/OFlow/

Trying it out

Have JeVois point towards an otherwise static scene, and swipe one finger in front of it, either moving from left to right of the field of view, from top to bottom, etc to confirm the different greyscale values as described above.