An Approach to Convert NCL Applications into Stereoscopic 3D

Abstract

This paper presents and discusses the internal operation of NCLSC (NCL Stereo Converter): a tool to convert a 2D interactive multimedia application annotated with depth information to a stereoscopic-multimedia application. Stereoscopic-multimedia applications are those that codify both the left-eye and right-eye views, as required by stereoscopic 3D displays. NCLSC takes as input an NCL (Nested Context Language) document and outputs an NCL stereoscopic application codified in side-by-side or top-bottom format (both common input formats for 3DTV sets). NCL is the declarative language adopted in most Latin America countries for terrestrial digital TV middleware systems and the ITU-T H.761 Recommendation for IPTV services. However, the proposed approach is not restricted to NCL and can be used by other languages. The depth annotation allows for positioning each 2D graphical component in a layered (2.5D or 2D+depth) user interface. It is used by NCLSC to compute the screen parallax (offset) between the graphical elements in the left and right views of the resulting stereoscopic application. When the resulting application is presented on stereoscopic 3D displays, such screen parallax induces retinal disparity, which creates the illusion of floating flat-2D graphical elements. NCLSC does not require any additional native middleware support to run in currently available 3D-enabled TV sets. Moreover, NCLSC can adapt, at run-time, the output application to different display sizes, viewer distances, and viewer preferences, which are usually required for a proper balance between artistic effects and user experience.