title: Manually locating physical and virtual reality objects.
abstract: OBJECTIVE
  In this study, we compared how users locate physical and equivalent three-dimensional images of virtual objects in a cave automatic virtual environment (CAVE) using the hand to examine how human performance (accuracy, time, and approach) is affected by object size, location, and distance.
  
  
  BACKGROUND
  Virtual reality (VR) offers the promise to flexibly simulate arbitrary environments for studying human performance. Previously, VR researchers primarily considered differences between virtual and physical distance estimation rather than reaching for close-up objects.
  
  
  METHODS
  Fourteen participants completed manual targeting tasks that involved reaching for corners on equivalent physical and virtual boxes of three different sizes. Predicted errors were calculated from a geometric model based on user interpupillary distance, eye location, distance from the eyes to the projector screen, and object.
  
  
  RESULTS
  Users were 1.64 times less accurate (p < .001) and spent 1.49 times more time (p = .01) targeting virtual versus physical box corners using the hands. Predicted virtual targeting errors were on average 1.53 times (p < .05) greater than the observed errors for farther virtual targets but not significantly different for close-up virtual targets.
  
  
  CONCLUSIONS
  Target size, location, and distance, in addition to binocular disparity, affected virtual object targeting inaccuracy. Observed virtual box inaccuracy was less than predicted for farther locations, suggesting possible influence of cues other than binocular vision.
  
  
  CONCLUSIONS
  Human physical interaction with objects in VR for simulation, training, and prototyping involving reaching and manually handling virtual objects in a CAVE are more accurate than predicted when locating farther objects.
authors.forename: Karen B
authors.initials: KB
authors.lastname: Chen
authors.forename: Ryan A
authors.initials: RA
authors.lastname: Kimmel
authors.forename: Aaron
authors.initials: A
authors.lastname: Bartholomew
authors.forename: Kevin
authors.initials: K
authors.lastname: Ponto
authors.forename: Michael L
authors.initials: ML
authors.lastname: Gleicher
authors.forename: Robert G
authors.initials: RG
authors.lastname: Radwin
mesh_terms: D000328:Adult; D003198:Computer Simulation; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D010812:Physical Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D014584:User-Computer Interface; D015348:Vision, Binocular / Q000502:physiology; D055815:Young Adult