This special issue is dedicated to highlighting recent advances in VR software and technology. The issue received 16 submissions, and some of which were significant extensions of the best papers from the ACM Symposium on Virtual Reality Software and Technology (VRST) 2014, which was held in Edinburgh, on 11–13 November 2014. All the submissions went through strict peer review, and five were ultimately selected to be included here. Many VR/AR applications use marker/tag tracking (such as probe tracking and calibration). The article “Illumination Independent and Accurate Marker Tracking Using Cross-Ratio Invariance” by Vincent Agnus, Stéphane Nicolau, and Luc Soler presents a novel method that focuses on accurately locating the corners of markers or tags using crossratio invariance. Cross-ratio invariance defines a ratio based on the intensity of collinear points that should remain constant, regardless of illumination changes. This approach improves tracking accuracy, particularly along the camera depth axis, up to several millimeters, depending on the marker depth. The advent of consumer stereoscopic headmounted displays (HMDs) like Oculus Rift opens up hitherto unexplored ways to use them in VR/ AR applications. However, 80 percent of users still report adverse physical discomfort or “simulator (motion) sickness” when using such devices. In “Reducing Visual Discomfort in HMDs Using Dynamic Depth of Field,” Kieran Carnegie and Taehyun Rhee study the use of blur effects in decreasing viewer discomfort. Depth of focus blur effects has been studied not only for general visual discomfort as well as symptoms such as fatigue, headache, and eye strain. Their study shows that DoF blur can considerably alleviate most of these discomforts, thereby reducing simulator sickness on the whole. This work has the potential to advance the widespread adoption of VR. Digitap is an eyes-free, wrist-worn input device that can robustly detect thumb-to-finger taps at different locations on the fingers. In “Sensing Thumb-to-Finger Taps for Symbolic Input in VR/AR Environments,” Manuel Prätorius, Ulrich Burgbacher, Dimitar Valkov, and Klaus Hinrichs present an advanced version of the DigiTap device