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Fusion of radar and optical images for person screening in security sensitive environments

 
: Fatihi, N.; Hantscher, S.; Lang, S.; Essen, H.

Electromagnetics Academy, Cambridge/Mass.:
Progress in Electromagnetics Research Symposium, PIERS 2012. Abstracts : March 27-30, 2012, Kuala Lumpur, Malaysia
Cambridge/Mass.: Electromagnetics Academy, 2012
ISBN: 978-1-934142-19-6
S.333
Progress in Electromagnetics Research Symposium (PIERS) <2012, Kuala Lumpur>
Englisch
Abstract
Fraunhofer FHR

Abstract
Recent terror attacks showed the vulnerability of our public life. That is why, a lot of security systems have been developed; especially for person screening on airports. However, sometimes images with anatomic details are produced violating the human privacy rights. To avoid it, mostly stylised avatars are shown on which the locations of the detected prohibited items on the body are marked. This, however, gives only a coarse orientation. In this paper, a better way is proposed by fusing the images of a radar sensor and an optical sensor. The radar image is generated by a rotating millimetre wave FMCW radar operating between 96 GHz and 99 GHz. It consists of a one transmitter and five receivers in order to scan the person from different aspect angles. The RF front end consists of a monolithic microwave integrated circuit with a chip size of 2x3 mm. The circuit features coplanar technology and cascode HEMTs for compact size and low cost. The optical image is generated by a time of flight (ToF) camera system which is able to measure the distance between the camera and a reflecting point by measuring the elapsed time. Hence, the ToF principle is quite similar to a radar (active ranging system), that needs an illumination source. To measure the distances, the light has to be modulated adequately. Then, it is possible to evaluate it as the modulation of the back-scattered signal differs from that of the emitted one. Mostly, the near infrared area is used for this purpose, because it is invisible and simultaneously not harmful for the human eye. Both, optical and radar image are superimposed showing the exact location of concealed objects worn under the cloths. For this purpose, perspective distortions are removed by a complex mathematic model considering the dimensions and the physical inner structure of the CMOS ToF chip array.

: http://publica.fraunhofer.de/dokumente/N-238595.html