Fig 1.
Egocentric distance perception using eye height and the angle of declination below the horizon to an object on the ground.
Fig 2.
If eye height is informed by vision (EHv) and continuously informed by visual information across various environmental contexts, the ratio between eye height and tangent of the angle of declination (AoDv) and therefore the distance remains the same.
Note: The camera symbol represents the manipulated virtual eye height in the VE.
Fig 3.
Prediction based on the use of a combination of the visually specified angle of declination (AoDv) and the postural eye height (EHpos) of the observer regardless of the potentially displayed environment.
In the case illustrated, underestimation of the distance is predicted, whereas for a lowered virtual EH overestimation of the distance is predicted. Note: The camera symbol represents the manipulated virtual EH.
Fig 4.
A: Experimenter showing the participant a meter stick with additional labels every 10 centimeters. B: Participant during the distance judgment task using the NVisor SX 60 HMD. C: The sparse-cue virtual environment used for Experiments 1–3. Note: The individuals in these images have given written informed consent (as outlined in PLOS consent form) to publish these case details.
Fig 5.
The effect of a manipulated virtual eye height (-50 cm or +50 cm) on egocentric distances in a standing position in comparison to the respective baseline condition (0 cm).
Error bars represent ±1 SE. The actual mean participant (postural) eye height in the experiment is depicted in the left upper corner. Note: (a) The predictions are shifted by the observed underestimation in the baseline condition to account for the usually observed distance underestimation in head mounted displays (in an ideal world, the 0 cm estimates would correspond to veridical performance). (b) If the virtual eye height were used, there should be no differences and the prediction for visual eye height would apply for all conditions.
Fig 6.
Participant judging distances in the sparse-cue virtual environment in a sitting posture.
The individual in this image has given written informed consent (as outlined in PLOS consent form) to publish these case details.
Fig 7.
The effect of a manipulated virtual eye height (+50 cm) on egocentric distances in a sitting posture in comparison to the respective baseline condition (0 cm).
Error bars represent ±1 SE. The actual mean participant (postural) eye height in the experiment is depicted in the left upper corner. Note: (a) The predictions are shifted by the observed underestimation in the baseline condition to account for the usually observed distance underestimation in head mounted displays (in an ideal world, the 0 cm estimates to veridical performance). (b) If the virtual eye height were used, there should be no differences and the prediction for visual eye height would apply for all conditions.
Fig 8.
Participant judging distances in the sparse-cue virtual environment in a lying prone posture on an adjustable hospital bed.
The individual in this image has given written informed consent (as outlined in PLOS consent form) to publish these case details.
Fig 9.
The effect of a manipulated virtual eye height (-50 cm or +50 cm) on egocentric distances in a prone position on a bed (adjusted to be approximately at seated eye height) in comparison to the respective baseline condition (0 cm).
Error bars represent ±1 SE. The actual mean participant (postural) eye height in the experiment is depicted in the left upper corner. Note: (a) The predictions are shifted by the observed underestimation in the baseline condition to account for the usually observed distance underestimation in head mounted displays (in an ideal world, the 0 cm estimates would correspond to the prediction, which is veridical performance). (b) If the virtual eye height were used, there should be no differences and the prediction for visual eye height would apply for all conditions.
Fig 10.
Mean ratio adjusted/actual eye height for the tested environments.
Error bars represent ±1 SE.
Fig 11.
Verbal estimates of different virtual eye heights in the rich-cue (black circles) and sparse-cue (blue squares) environment. Error bars represent ±1 SE.