The present literature review focusses at two issues. Chapters 2 and 3 discuss the effects of indirect viewing and viewing deficits on driving behaviour. To order the available data, a distinction is made between peripheral vision and foveal vision. Restriction of peripheral vision (i.e. field of view) will degrade course control, speed estimation, and time to contact estimates. Degraded foveal vision (contrast and resolution) will affect lane keeping and object detection. Since direct evidence for the effects of image quality degradation related to indirect viewing systems is scarce, part of the conclusions is based on indirect evidence such as the relation between vision deficits and accidents. An important aspect in this respect is the fact that drivers with visual deficits are able to adjust their driving behaviour (e.g. reducing their speed, or avoiding driving at night), which reduces the correlations in accident analyses. However, this observation also shows that drivers are able to make the best of degraded visual information. Besides field size and image quality, stereo vision may be an important parameter for indirect viewing systems. For this parameter little experimental data are available. This is especially true for data on the relation between stereo vision and off-the-road driving. However, it is expected that the role of stereo vision increases under degraded visual conditions. The second issue that is reviewed here is the use of head-slaved systems in vehicles. This issue is very relevant if the system employs movable cameras. An ecological approach to controlling the viewing direction of cameras is to make them head-slaved. Such a control mechanism is thought to enlarge the situational awareness of the driver, and reduce the occurrence of disorientation. However, employing a head-slaved system in combination with a head-mounted display, may also have less favourable aspects, regarding e.g. the weight on the head, visual comfort, and the effects of vehicle vibration. (Author/publisher)
Abstract