Design and evaluation of methods to prevent frame cancellation in real-time stereoscopic rendering

Frame cancellation comes from the conflict between two depth cues: stereo disparity and occlusion with the screen border. When this conflict occurs, the user suffers from poor depth perception of the scene. It also leads to uncomfortable viewing and eyestrain due to problems in fusing left and right images. In this paper we propose a novel method to avoid frame cancellation in real-time stereoscopic rendering. To solve the disparity/frame occlusion conflict, we propose rendering only the part of the viewing volume that is free of conflict by using clipping methods available in standard real-time 3D APIs. This volume is called the "Stereo Compatible Volume" (SCV) and the method is named "Stereo Compatible Volume Clipping" (SCVC). Black Bands, a proven method initially designed for stereoscopic movies is also implemented to conduct an evaluation. Twenty two people were asked to answer open questions and to score criteria for SCVC, Black Bands and a Control method with no specific treatment. Results show that subjective preference and user\´s depth perception near screen edge seem improved by SCVC, and that Black Bands did not achieve the performance we expected. At a time when stereoscopic capable hardware is available from the mass consumer market, the disparity/frame occlusion conflict in stereoscopic rendering will become more noticeable. SCVC could be a solution to recommend. SCVC\´s simplicity of implementation makes the method able to target a wide range of rendering software from VR application to game engine.