Omnidirectional Stereo Rendering of Virtual Environments

Lukas Meindl
Omnidirectional Stereo Rendering of Virtual Environments
[thesis]

Information

Abstract

In this thesis we discuss the use of omnidirectional stereo (omnistereo) rendering of virtual environments. We present an artefact-free technique to render omnistereo images for the CAVE in real time using the modern rendering pipeline and GPU-based tessellation. Depth perception in stereoscopic images is enabled through the horizontal disparities seen by the left and right eye. Conventional stereoscopic rendering, using off-axis or toe-in projections, provides correct depth cues in the entire field of view (FOV) for a single view-direction. Omnistereo panorama images, created from captures of the real world, provide stereo depth cues in all view direction. This concept has been adopted for rendering, as several techniques generating omnistereo images based on virtual environments have been presented. This is especially relevant in the context of surround-screen displays, as stereo depth can be provided for all view directions in a 360° panorama simultaneously for upright positioned viewers. Omnistereo rendering also lifts the need for view-direction tracking, since the projection is independent of the view direction, unlike stereoscopic projections. However, omnistereo images only provide correct depth cues in the center of the FOV. Stereo disparity distortion errors occur in the periphery of the view and worsen with distance from the center of the view. Nevertheless, due to a number of properties of the human visual system, these errors are not necessarily noticeable. We improved the existing object-warp based omnistereo rendering technique for CAVE display systems by preceding it with screen-space adaptive tessellation methods. Our improved technique creates images without perceivable artefacts and runs on the GPU at real-time frame rates. The artefacts produced by the original technique without tessellation are described by us. Tessellation is used to remedy edge curvature and texture interpolation artefacts occurring at large polygons, due to the non-linearity of the omnistereo perspective. The original approach is based on off-axis projections. We showed that on-axis projections can be used as basis as well, leading to identical images. In addition, we created a technique to efficiently render omnistereo skyboxes for the CAVE using a pre-tessellated full-screen mesh. We implemented the techniques as part of an application for a three-walled CAVE in the VRVis research center and compared them.

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BibTeX

@mastersthesis{MEINDL-2015-OSR,
  title =      "Omnidirectional Stereo Rendering of Virtual Environments",
  author =     "Lukas Meindl",
  year =       "2015",
  abstract =   "In this thesis we discuss the use of omnidirectional stereo
               (omnistereo) rendering of virtual environments. We present
               an artefact-free technique to render omnistereo images for
               the CAVE in real time using the modern rendering pipeline
               and GPU-based tessellation. Depth perception in stereoscopic
               images is enabled through the horizontal disparities seen by
               the left and right eye. Conventional stereoscopic rendering,
               using off-axis or toe-in projections, provides correct depth
               cues in the entire field of view (FOV) for a single
               view-direction. Omnistereo panorama images, created from
               captures of the real world, provide stereo depth cues in all
               view direction. This concept has been adopted for rendering,
               as several techniques generating omnistereo images based on
               virtual environments have been presented. This is especially
               relevant in the context of surround-screen displays, as
               stereo depth can be provided for all view directions in a
               360° panorama simultaneously for upright positioned
               viewers. Omnistereo rendering also lifts the need for
               view-direction tracking, since the projection is independent
               of the view direction, unlike stereoscopic projections.
               However, omnistereo images only provide correct depth cues
               in the center of the FOV. Stereo disparity distortion errors
               occur in the periphery of the view and worsen with distance
               from the center of the view. Nevertheless, due to a number
               of properties of the human visual system, these errors are
               not necessarily noticeable. We improved the existing
               object-warp based omnistereo rendering technique for CAVE
               display systems by preceding it with screen-space adaptive
               tessellation methods. Our improved technique creates images
               without perceivable artefacts and runs on the GPU at
               real-time frame rates. The artefacts produced by the
               original technique without tessellation are described by us.
               Tessellation is used to remedy edge curvature and texture
               interpolation artefacts occurring at large polygons, due to
               the non-linearity of the omnistereo perspective. The
               original approach is based on off-axis projections. We
               showed that on-axis projections can be used as basis as
               well, leading to identical images. In addition, we created a
               technique to efficiently render omnistereo skyboxes for the
               CAVE using a pre-tessellated full-screen mesh. We
               implemented the techniques as part of an application for a
               three-walled CAVE in the VRVis research center and compared
               them.",
  month =      nov,
  address =    "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria",
  school =     "Institute of Computer Graphics and Algorithms, Vienna
               University of Technology ",
  keywords =   "virtual reality, stereo rendering",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2015/MEINDL-2015-OSR/",
}