Faber, Petko 
  
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Petko Faber 
Institute of Photogrammetry, University of Bonn, 
Nussallee 15, 53115 Bonn, Germany 
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IMAGE-BASED PASSENGER DETECTION AND LOCALIZATION INSIDE VEHICLES 
npf@ipb.uni-bonn.de | 
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Working Group V/III 
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KEY WORDS: intelligent airbag system, least squares method, ellipsoid. fo 
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ABSTRACT T 
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In our paper we describe the ongoing research to develop an intelligent airbag system. Using image sequences acquired 1 
from a stereo camera, we detect the form and the position of the driver and passenger seat. And, if a seat is classified as Ww 
occupied, we try to estimate the geometry and position of the human's head as the most distinguishing feature of the body, | 
if it is possible. Ir 
The developed software system consists of five steps: the correction of distortions followed by an epipolar rectification of O 
the stereo images, the feature extraction, the feature-based matching, the seat occupation detection and verification, and | p 
the approximation of the human's head. The emphasis in this paper is on the used model to approximate the human's | Vi 
head by an ellipsoid. The base of a subset of the estimated features as well as a certain assignment of the features to a ir 
human’s head. The used model bases on the least square method with a condition, which supports the approximation of b 
an ellipsoid. To determine, if an obtained approximation is valid the result is compared with the standard dimensions of | Se 
a human's head. On tests on numerous image sequences recorded inside different vehicles the feasibility of the system is | a 
shown. The information about the seat occupation and the location of the detected passengers inside the vehicle can be C 
used to control an intelligent airbag deployment. | 
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Figure 1: Possible scenarios seen by a camera inside a vehicle, which are of special interest for an intelligent airbag | ! 
deployment. 
1 INTRODUCTION 
Airbags can save or kill. Does your airbag know the difference? During the pre-crash braking, a passenger may be thrown \ 
against the dashboard area in immediate proximity to the airbag. On the other hand, an airbag inflates in less than 1/25th 
of a second. The energy required to inflate an airbag can seriously or even fatally insure driver and passenger who are 
too close to the airbag as they begin to inflate. It is important to understand that injuries occur because of passengers's | 
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positions when the airbag begins to deploy, not because of passengers’s sizes or ages. Anyone on top of, or very close to, 
the airbag is at risk. 
In (1) and (2) various aspects are reported about the effectiveness of occupant protection systems like safety belts and 
airbags and their use. The National Highway Traffic Safety Administration estimates that more than 4750 people are alive 
today because of their airbag. Driver deaths are being reduced by about 14 percent. But also 148 deaths are reported since 
1990, caused by airbags which are deployed in low severity crashes. These deaths include 36 unbelted drivers, 4 unbelted 
  
230 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000.