High Dynamic Range Displays improve the realism of motion cues in night driving simulators

Abstract

Night driving is challenging for driving simulations. At night, the constraints on Computer Graphics performance are unusually strong, as many relevant details have low contrasts and low luminance values, while the overall contrast is very high, due to light sources from road lighting and vehicle headlamps. Some level of realism is needed in terms of contrast rendering, because contrast impacts visibility and motion perception, which in turn impact the driving behavior. This is usually achieved in Computer Graphics with Tone Mapping Operators (TMOs), in order to display the computed images on a standard, Low Dynamic Range (LDR) display device. We explore in this paper the drawbacks of these operators for nighttime driving simulations, focusing on motion cues, and discuss the potential benefit of the emerging technology of High Dynamic Range (HDR) display devices.We have focused on a night-time road environment with an incoming motorcycle. Two experiments have been conducted, with 33 participants. Time-to-Collision (TTC) was considered as a proxy for motion perception. TTC estimations were collected on a HDR display and compared to degraded visual environments. The first experiment shows that the visibility of the motorcycle’s outline is the main visual cue for the TTC estimation in nighttime conditions (but this doesn’t happen with cars). It suggests that the main drawbacks of TMOs with respect to TTC estimation involves the mapping of low contrasts, which either enhances or impairs the motorcycle visibility. The second experiment explores this hypothesis and shows that enhancing the visibility of the motorcycle leads to biases in the TTC estimation, whereas removing it does not impact the TTC estimation — at the cost of other realism problems. These results suggest that motion cues at night are more realistic with a HDR Display, and that such display devices may be useful in situations where a realistic perception of hardly visible contrasts is needed.