Wider is better but sharper is not: optimizing the image of camera-monitor systems

Abstract

The replacement of rear-view mirrors with camera-monitor systems introduces new opportunities for design, such as altering the image quality and the rearward field-of-view. We investigated how the image quality and field-of-view might affect the distance and time-to-contact estimation of other vehicles. Eighty-six subjects estimated either their egocentric distance to a stationary vehicle (Experiment I) or the time-to-contact to an approaching vehicle (Experiment II). Throughout the experiments, the pixel density and either the field-of-view or the viewing condition varied. A larger field-of-view increased distance estimation accuracy and confidence. Reduced pixel density led to larger estimates. In contrast, reduced pixel density and simulated dirt shortened time-to-contact estimates. This is compatible with a safety strategy applied under conditions of impaired vision. Moreover, a limited benefit was observed for higher pixel densities. Therefore, camera-monitor systems with large field-of-view and a pixel density of around 300 ppi could ensure accurate TTC and distance estimation.

Practitioner summary: A camera’s field-of-view and image quality are important parameters for camera-monitor systems. In two experiments, we investigated the effects of these two parameters on rearward distance and time-to-contact estimation. Whereas a larger field-of-view improved distance estimation accuracy, increasing the pixel density had a limited effect in the estimation of time-to-contact.

Keywords:

• Camera-monitor systems
• camera resolution
• field-of-view
• design recommendations
• time-to-contact estimation

Acknowledgements

We thank Klaus Landwehr and Daniel Oberfeld for their assistance in data analysis and Marlene Wessels for proofreading. Moreover, we wish to thank Agnes Münch for her programming support. Finally, we thank all volunteers who participated in our experiments.

Disclosure statement

In accordance with Taylor & Francis policy and our ethical obligation as researchers, we report that there are no potential competing interests to declare.

Data availability statement

The authors confirm that summary statistics supporting the findings of this study are available within the article’s supplementary material. The raw data that support the findings of this study are available from the corresponding author, CB, upon reasonable request.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.