Design of Visual Displays for Driving Simulator Research G. John Andersen Department of Psychology University of California, Riverside

Vision Issues in Driving Simulators Driving tasks require accurate perception of depth and distance in the 3D scene –What sources of information are critical –Integration of sources –Conflict between sources Visual Display –Display characteristics (Aliasing, Flicker, Update,Refresh, Resolution)

Failure to Consider these issues in Driving Simulators Poor task performance Low external validity of results Poor transfer of training Increased risk of simulator sickness

Driving tasks and Perception of Depth and Distance

, 96 Cutting, 1996 Depth Contrast Depth (meters) Occlusion Size constancy Cast Shadows Disparity Motion parallax Convergence Aerial

Overall scene depth Layout of Objects Properties of Objects Viewer-centered Information Accommodation Linear Perspective Disparity Motion Parallax Linear Perspective Relative Size Motion Parallax Texture (perspective) Specular Highlights Object-centered Information Surrounding Frame Compression Gradient Structure from Motion Compression Gradient Structure from Motion Texture (non-perspective) Shading Andersen, Braunstein, & Saidpour, 1998

Driving Tasks and Perception Multiple sources of information available for driving tasks –What information is critical for what tasks Multiple sources for a specific task Different tasks require different information sources –Use of multiple sources Cue interactions Cue conflicts

Multiple sources for a specific task: Collision Detection Model based on analysis of visual information available to driver (Andersen & Sauer, 2004) –Use of 5 parameters  motion parallax; optic flow) d  /dt (motion parallax; optic flow)  d  /dt d s (texture gradients, disparity, relative size)

Front View Top View t=1 t=0    specifies the time to contact during constant velocity collisions

a  is the bearing of an object relative to a reference

 d  dt, d s d  /dt,  d  /dt,  d  dt, d s   d  dt, d s  d  /dt,  d  /dt,  d  dt, d s d  dt  d s d  dt, d s  d  dt, d s  d  /dt, d s d  dt d  /dt,  d  dt, d s d  /dt,  d  /dt, d s d  dt d  /dt  d  /dt,  d  dt, d s Vehicle Motion Object Motion F = Fixed Speed V = Variable Speed S = Straight Path C = Curved Path No F/S V/S F/C V/C NoF/SV/SF/CV/C

Is  =0? Or d  /dt  0?(constant angular direction) Is  >0? (expansion)? Ye s No Ye s Is d  /dt =0? (Constant expansion) No Deriv e d  /dt Is d  /dt >=-0.5? No Collision Object Derive d v -d s Is d v -d s >0? Ye s Non- collision Object Deriv e  Derive  d  /dt (angular direction) Is d v -d s =0? (Constant expansion) No Ye s Select Object

Different tasks and different sources of information Two tasks with different sources of information - Collision Detection (constant speeds and linear trajectories): Optical Expansion (TTC) and  -Vehicle Speed: Edge Rate Question: Does information from one task affect use of information for second task

Experiment Issue: Does information for one task affect use of information for a different task Task: collision detection Independent Variables –Collision or non-collision object –Time to contact (TTC) –Different combinations of vehicle speed and object speed Dependent variable –Sensitivity (d’)

Simulators depict a 3D world Perception of 3D scene includes -Texture gradients -Motion parallax -Occlusion -other information sources

Visual system also has cues for perceiving the distance to the display

3 Information sources for depth and distance of Display - Binocular Disparity - Eye convergence - Accommodation

, 96 Cutting, 1996 Depth Contrast Depth (meters) Occlusion Size constancy Cast Shadows Disparity Motion parallax Convergence Aerial Accommodation

Visual Cue Conflicts between display cues and 3D scene cues Visual Cue conflict: - Disparity, convergence and accommodation information specify display is flat - Motion parallax, texture gradients, and other cues specify scene is 3D

Human Factors Solutions to these Issues Determine perceptual information needed for driving tasks of interest Design displays to optimize performance of tasks –Consider interactions of different information sources Minimize cue conflicts Design for optimal performance not for high fidelity –Question need of high fidelity rendered scenes, control dynamics and fixed/variable base simulator