12.9Discussion 195
OtherOptimizationApproaches
As surveyed by Bulbul et al. [2008], graphics-pipeline-based and image-based
optimization solutions have also been proposed. Graphics-pipeline-based optimi-
zations make use of the coherence between views, or they are based on approxi-
mate rendering where fragment colors in all neighboring views can be
approximated from a central view when possible. In image-based optimizations,
one view is reconstructed from the other view by exploiting the similarity be-
tween the two. In these techniques, the rendering time of the second image de-
pends on only the image resolution, instead of the scene complexity, therefore
saving rendering computations for one view. Approaches have been proposed
that are based on warping, depth buffers, and view interpolation [Bulbul et al.
2008].
12.9Discussion
MultiviewSceneSetup
Our architecture supports customization and extensible parameterization, but
does not further provide guidelines on how to set the multiview camera parame-
ters and scene in order to achieve maximum viewing comfort. In the first volume
of Game Engine Gems, Hast [2010] describes the plano-stereoscopic view mech-
anisms, common stereo techniques such as anaglyph, temporal multiplexing
(shutter glasses), and polarized displays and discusses their pros and cons. Some
key points are that contradicting depth cues should be avoided and that special
care needs to be directed at skyboxes and skydomes, billboards and impostors,
GUIs, cursors, menus in virtual 3D space, frame rate, view synchronization, and
scene-to-scene camera setup consistency (such as focal distance). Viewers may
have different eye separation distances and display sizes, and the distance of the
viewer to the display can differ among different platforms. It should be kept in
mind that creating the right 3D feeling is a process that requires a scalable tech-
nical infrastructure (as presented in this chapter) and an analysis of the target
platforms, the virtual scene, and animations.
Enabling/DisablingMultiviewRenderingatRunTime
It is important to allow the user to select single-view rendering if the hardware
supports it; some users [Hast 2010] may not be able to accommodate the mul-
tiview content easily and may prefer single-view rendering because it can pro-
duce a higher-quality image. The architecture natively supports switching