@conference {Benamar20135, title = {Gradient-based time to contact on paracatadioptric camera}, booktitle = {2013 IEEE International Conference on Image Processing, ICIP 2013 - Proceedings}, year = {2013}, note = {cited By 2}, pages = {5-9}, abstract = {The problem of time to contact or time to collision (TTC) estimation is largely discussed in perspective images. However, a few works have dealt with images of catadioptric sensors despite of their utility in robotics applications. The objective of this paper is to develop a novel model for estimating TTC with catadioptric images relative to a planar surface, and to demonstrate that TTC can be estimated only with derivative brightness and image coordinates. This model, called {\textquoteright}gradient based time to contact{\textquoteright}, does not need high processing such as explicit estimation of optical flow and feature detection and/or tracking. The proposed method allows to estimate TTC and gives additional information about the orientation of planar surface. It was tested on simulated and real datasets. {\textcopyright} 2013 IEEE.}, doi = {10.1109/ICIP.2013.6738002}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897697160\&doi=10.1109\%2fICIP.2013.6738002\&partnerID=40\&md5=2d096a6f98a59c3c442f3c24ffca4bbc}, author = {Benamar, F.a d and El Fkihi, S.a b and Demonceaux, C.c and Mouaddib, E.d and Aboutajdine, D.a} }