Speed, Motion, Pursuit, and Depth (Visual Depth Perception 15)
This Demonstration shows absolute depth from your choice of pursuit rate and motion rate for the case of a fixate and distractor on the axis and an observer moving at 6.5 cm/sec (interocular distance per second) to the right on the axis. The motion/pursuit ratio of "Speed, Pursuit, M/P Ratio, and Depth (Visual Depth Perception 16)" is known to be what the brain uses to estimate relative depth, even though retinal motion and smooth eye pursuit are separate geometric inputs to the brain.
This Demonstration is for the case of a fixate and distractor on the axis and an observer moving at speed 6.5 cm/sec (interocular distance per second) to the right on the axis.
If you know the speed, pursuit determines absolute fixate distance; for example, at speed ,
, so .
Once you know , motion determines by the formula
All the points on the red line have the same M/P ratio and same relative depth. The brown curves have the same and the vertical blue lines have the same .
We classify this Demonstration as "speculation" because we do not know a way for an observer to determine speed from visual clues. Without speed (or ) the motion/pursuit law can only find relative depth, .