PX4Flow (Optical Flow): Get raw data - array of optical flow vectors

If I understand px4flow docs (Redirecting to latest version of document (master)) correctly, it outputs mainly the general flow_x and flow_y numbers (and some values calculated from that).

Is it possible to get out of px4flow the array of vectors calculated across the grid of the image. Something like this (visualized):

(image source: http://www.hizook.com/blog/2010/02/16/learning-estimate-robot-motion-and-find-unexpected-objects-optical-flow )