Detection of linear ego-acceleration from optic flow

Date Submitted Jun 11, 2012          Publication Year 2017         
F. Festl, F. Recktenwald, C. Yuan and H. A. Mallot

Human observers are able to estimate various ego-motion parameters from optic flow, including rotation, translational heading, time to collision (TTC), time to passage (TTP), etc. The perception of linear ego-acceleration or deceleration, i.e. changes of translational velocity, is less well understood. While time-to-passage experiments indicate that ego-acceleration is neglected, subjects are able to keep their (perceived) speed constant under changing conditions, indicating that some sense of ego-acceleration or velocity change must be present. In this paper, we analyze the relation of ego-acceleration estimates and geometrical parameters of the environment using simulated flights through cylindrical and conic (narrowing or widening) corridors. Theoretical analysis shows that a logarithmic ego-acceleration parameter, called the acceleration rate, can be calculated from retinal acceleration measurements. This parameter is independent of the geometrical layout of the scene; if veridical ego-motion is known at some instant in time, acceleration rate allows to update ego-motion without further depth-velocity calibration. Results indicate, however, that subjects systematically confuse ego-acceleration with corridor narrowing and ego-deceleration with corridor widening, while veridically judging ego-acceleration in straight corridors. We conclude that judgments of ego-acceleration are based on first order retinal flow, and do not make use of acceleration rate or retinal acceleration.

Detection of linear ego-acceleration from optic flow,

F. Festl, F. Recktenwald, C. Yuan, and H. A. Mallot

Journal of Vision, 12(7), 1-12, 2012.
DOI: 10.1167/12.7.10