In English

Image processing for pedestrian detection using a high mounted wide-angle camera

Johansson Martin
Göteborg : Chalmers tekniska högskola, 2014. 102 s.
[Examensarbete på avancerad nivå]

The purpose of this thesis has been to develop a automated pedestrian detection system for high mounted wide angle cameras on a Volvo truck, and prove its functionality for pedestrian detection in urban environments. Two cameras at di erent heights have been evaluated: one middle mounted forward facing camera; and one top mounted side facing camera. The thesis presents a framework of combining several independent algorithms fused into a uni ed decision for the presence of a pedestrian. For the forward facing camera a evaluation of image distortion was rst made. Two background subtraction techniques were implemented and compared: the Mixture of Gaussians, and the Codebook method. Further, two object classi cation methods were compared: the Viola & Jones method where salient features of pedestrians are captured by an overcomplete set of Haar-like wavelet features and chosen by the gentle AdaBoost training algorithm; and the continuation of this method by Dollar et al.. To handle the in-plane distortion a rotational scheme was evaluated and setup that resulted in ve di erent classi er regions. The system was trained on pedestrian images captured around Lindholmen in Gothenburg, Sweden. Finally, tracking was incorporated in the form of Kalman ltering. For the side camera two new classi ers were trained based on the pedestrian bounding box viewing angle. An example interface was also developed that displays the nal uni ed decision with a color bounding box warning system based on pedestrian proximity, the current active systems, a distance measure, and tracking history. Evaluation data was captured to test and verify the pedestrian detection and tracking method under normal urban environments. Experimental evaluation of the system on a conventional 2.16 GHz Intel Core2 CPU operating on 720576 pixel images shows result of a robust detection and tracking system for pedestrians of di erent sizes, rotations and postures - with fast enough algorithms suitable for on-line operation.

Nyckelord: Automotive safety, Computer Vision, Image Processing, Pedestrian detection, Wide-angle lens, Machine Learning, Classification,

Publikationen registrerades 2014-09-16.

CPL ID: 202800

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