Guest Editors' Introduction: Special Section on the ACM Symposium on Virtual Reality and Software Technology (VRST 2009)

THIS special section is dedicated to the three Best Papers of VRST 2009, which was held in Kyoto, Japan from 18 to 20 November 2009. The papers were first selected by a jury based on the referees’ reports and the oral presentation. The authors were then asked to provide an extended version. The extended papers were then reviewed through a strict peer review process. The first paper, “Robust Relocalization and Its Evaluation for Online Environment Map Construction” by Sehwan Kim, Christopher Coffin, and Tobias Höllerer from the University of California in Santa Barbara, presents robust methodology and evaluation for camera orientation relocalization, using virtual keyframes for online environment map construction. In case of tracking loss, incoming camera frames are matched against known-orientation keyframes to reestimate camera orientation. Instead of solely using real keyframes from incoming video, the proposed approach employs virtual keyframes which are distributed strategically within completed portions of an environment map. The authors compare different system variants using three evaluation methods to show that the proposed system is useful in a practical sense. To improve recovery robustness against lighting changes in indoor and outdoor environments, they propose a new approach based on illumination normalization and saturated area removal. In the second paper, “Natural Perspective Projections for Head-Mounted Displays,” Frank Steinicke, Gerd Bruder, Scott Kuhl, Pete Willemsen, Markus Lappe, and Klaus H. Hinrichs from Munster University in Germany analyze the user’s perception of a virtual environment displayed in a Head Mounted Displayed (HMD), which is rendered with different geometric fields of views. They introduce a psychophysical calibration method to determine the HMD’s actual field of view, which may vary from the nominal values specified by the manufacturer. Furthermore, we conducted two experiments to identify perspective projections for HMDs, which are identified as natural by subjects—even if these perspectives deviate from the perspectives that are inherently defined by the display field of view. In the third paper, “A Wide-View Parallax-Free EyeMark Recorder with a Hyperboloidal Half-Silvered Mirror and Appearance-Based Gaze Estimation,” Hiroki Mori, Erika Sumiya, Tomohiro Mashita, Kiyoshi Kiyokawa, and Haruo Takemura from Osaka University propose a wideview parallax-free eye-mark recorder with a hyperboloidal half-silvered mirror and a gaze estimation method suitable for the device. Their eye-mark recorder provides a wide field-of-view video recording of the user’s exact view by positioning the focal point of the mirror at the user’s viewpoint. They implemented and evaluated a gaze estimation method for their eye-mark recorder. They apply principal component analysis and multiple regression analysis to determine the relationship between the captured images and their corresponding gaze points.