Game Engine Gems 2

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12

AGenericMultiviewRendering

EngineArchitecture

M. Adil Yalçın

Tolga Çapın

Department of Computer Engineering, Bilkent University

12.1Introduction

Conventional monitors render a single image, which is generally observed by the

two eyes simultaneously. Yet, the eyes observe the world from slightly different

positions and form different images. This separation between the eyes provides

an important depth cue in the real world. Multiview rendering aims to exploit this

fundamental feature of our vision system for enhanced 3D rendering.

Technologies that allow us to send different images to the two eyes have

been around for years, but it is only now that they can reach the consumer level

with higher usability [Bowman et al. 2004]. The existing technologies vary

among the different types of 3D displays, and they include shutter glasses, binoc-

ular head-mounted displays, and the more recent and popular autostereoscopic

displays that require no special glasses.

Recent techniques for multiview rendering differ in terms of visual character-

istics, fidelity, and hardware requirements. Notably, multiview rendering engines

should be able to support more than two simultaneous views, following recent

3D display technologies that can mix a higher number of simultaneous views

than traditional stereo view [Dodgson 2005].

Currently, many available multiview applications are configured for the ste-

reo-view case, and the routines that manage stereo rendering are generally im-

plemented as low-level features targeted toward specific APIs and displays. We

present a higher-level multiview rendering engine architecture that is generic,

robust, and easily configurable for various 3D display platforms, as illustrated in

180 12.AGenericMultiviewRenderingEngineArchitecture

Figure 12.1. A torus rendered for different basic 3Ddisplay platforms.

Figure 12.1. The architecture simplifies the use of multiview components of a

rendering engine and it solves the problems of rendering separate views and

merging them for the target display. It also includes support for multiview ren-

dering optimization techniques, such as view-specific level-of-detail systems and

pipeline modifications. Additional discussions include insights on further exten-

sions, design guidelines, and other possible uses of the presented architecture.

Most of the discussions, terminologies, and guidelines in this chapter follow

OpenGL conventions. The implementation of the architecture is included in the

OpenREng library,

1

an open-source rendering engine based on modern desktop

and mobile OpenGL specifications with multiview rendering support, and the

sample applications are built using this library.

12.2AnalyzingMultiviewDisplays

At its core, rendering for 3D displays aims to generate separate images (views)

for separate eyes. All types of 3D displays, summarized below, create the illusion

of 3D space based on multiplexing the different images for each eye, whether it

be temporally, spatially, or in color. It is a challenge to support all types of dis-

plays transparently to application implementations in a way that hides the details

of the low-level resource management required for multiview rendering.

Displays that require wearing special eyeglasses can be subdivided into the

following categories (as also shown in Figure 12.2):

1

See http://openreng.sourceforge.net/.

Mono

Parallax-based

Lenticular-based

Anaglyph-based