The Ups and Downs of Camera-Monitor Systems: The Effect of Camera Position on Rearward Distance Perception

Abstract

Objective This study investigates the effects of different positions of side-mounted rear-view cameras on distance estimation of drivers. Background Camera-monitor systems bring advantages as compared to conventional rear-view mirrors, such as improved aerodynamics and enlarged field-of-view. Applied research has mainly focused on the comparison between cameras and mirrors or on positioning of in-vehicle monitors. However, the positioning of the exterior camera awaits investigation given that the perspective of the observer at does affect depth perception at large. Method In two experiments, a total of 50 students estimated metric distances to static vehicles presented in realistic or 3D-rendered pictures. The pictures depicted the rearward scene of a car following the driver as viewed through a camera at varying vertical and horizontal positions. The following vehicle’s size and environmental information varied among conditions and experiments. Results Lower camera positions led to distance overestimation and higher positions to underestimation. The effect increased as the distance to the following vehicle decreased. Moreover, larger vehicles led to stronger distance underestimation, especially in low camera positions. Interestingly, the main effect of camera position disappeared when the ego-vehicles’ back was visible. Conclusion Different rearward viewpoints affect distance estimation of drivers, especially in close distances. However, a visible reference of one’s own vehicle seems to mostly compensate this effect. Application In general, the rear-view camera should be mounted rather higher and to the front of the vehicle. Also, the vehicle’s back should always be visible. Low camera positions are not recommended.

A new perspective on CMS – testing the effect of camera displacement in a realistic lane-change task

“…In sum, the results of the current experiment do not indicate large behavioral changes when slightly displacing the exterior camera in sedans. However, considering the small effects of the low camera position, we stay with the design recommendation formulated earlier (Bernhard & Hecht, 2020): Lower camera positions should be avoided, at least for larger vehicles. Future research should investigate the effects of camera position for larger amounts of vertical displacement as well as the preferences of users in order to identify the most appropriate mounting position of the exterior camera in CMS.…”

“…In other contexts, vertical perspective change has been shown to affect distance and time-to-contact estimation (Daum & Hecht, 2009;Hecht et al, 2015;Leyrer et al, 2015;Ooi et al, 2001;Steward et al, 1993). Effects on distance estimation also generalize to CMS (Bernhard & Hecht, 2020).…”

A Case for Raising the Camera: A Driving Simulator Test of Camera-Monitor Systems

“…As the viewpoint is raised (lowered), stationary observers underestimate (overestimate) their distance to a target. This holds for indoor environments (Corujeira & Oakley, 2013; Gardner & Mon-Williams, 2001; Ooi et al, 2001; Rand et al, 2011; Zhou et al, 2016), virtual environments (Leyrer et al, 2015; Li et al, 2011; Messing & Durgin, 2005), outdoor environments (Daum & Hecht, 2009), restricted viewing conditions (Barfield et al, 1995; Hendrix & Barfield, 1997; Vianin et al, 2004), and CMS (Bernhard & Hecht, 2020). Similar effects might surface in dynamic judgments that precede overtaking maneuvers.…”

“…According to the latest numbers, lane change crashes could account for around 4% to 10% of all crashes reported on U.S. roadways (Fitch et al, 2009), and for as much as 17% in Abu Dhabi (Shawky, 2020). Our earlier research indicated that vertical camera displacement affects drivers’ depth perception (Bernhard & Hecht, 2020). The experiment at hand strives to extend these findings with regard to lane change performance and subjective experience in a realistic driving maneuver.…”

“…The only evaluation of exterior camera displacement for CMS to date (Bernhard & Hecht, 2020) asked participants to judge metric distances to vehicles placed behind them. The position of the exterior camera was varied in up to five steps, with a maximum displacement of 125 cm away from the conventional mirror position.…”