Recursive rendering based infinite closed space virtual reality engine development

Virtual reality hardware has been in use for a while for applications where fidelity matters, like military simulations and medical applications. With the recent leaps in technology, virtual reality hardware costs decreased and the devices became more available to the regular users. In addition to simulation and training applications, virtual reality gained popularity in movie and game industries. This introduced new requirements for virtual reality hardware and applications. More intuitive military and medical simulations can be achieved with specialized hardware and environment. However, this is not always possible for a regular user with limited space and standard hardware. Mainstream virtual reality hardware is often designed for home usage with the assumption of it being used in regular rooms where the virtual movement cannot be achieved with the natural walking alone. Several virtual movement methods are developed to overcome space limitations. The most popular virtual locomotion methods are teleportation and shifting using controllers. While these methods solve the movement related problems, they introduce physiological problems such as naussea and dizziness, which are caused by mismatch of the perceived motion with the real movement. Past methods that resolve these side effects either requires specialized hardware or distorts the virtual environment. To solve these limitaions without side effects and requiring extra hardware, we propose a portal based overlapping environment method and defined an environment design ruleset for infinite spaces. We compared our proposed method to other natural walking based methods such as distraction and mapping. In addition to locomotion methods, low performance is also known to cause physiological side effects. We used the latest graphical application development interfaces while developing our grahics engine for significant performance improvement. Instead of OpenGL, which was designed with 1990s graphics architecture in mind and comes with a lot of technical debt caused by backward compatibility requirements, we opted to use Vulkan, which is entirely designed for modern graphics cards and multi core processors. Our portal based rendering engine is designed and optimized to be entirely compatible with these modern architechtures. In order to quantitatively compare performance difference, we also implemented a reference renderer in OpenGL. We observed that significant performance gains are achieved by using modern graphics technologies. In addition to performance comparisons, we conducted a user experience study to compare our portal based method to another modern environment mapping method. Most users preferred our method over the other one and gave positive feedbacks regarding its innovative approach.