GIS on virtual reality glasses with mobile map tools
Recently, Virtual Reality and Augmented Reality have become fields of increasing popularity, thanks to projects as Oculus, Google Glass or Microsoft Hololens. During the last months our team has work to include Virtual Reality features into the Glob3 Mobile (G3m) project. These new functionalities allow to explore the virtual earth created by the render engine of G3m and explore it from a first person perspective.
These features imply two major changes, adding head attitude tracking support, and enabling stereo rendering.
The first task implies recognizing the orientation of the device that serves as output screen and is attached to the head of the user. This is achieved by accessing the built-in gyroscopes and accelerometers present in most smartphones. The output of these sensors that track the orientation is fetched through the native API of the platforms iOS, Android and HTML5. In this work we implement an abstraction layer that unifies the attitude representation across all the platforms. This attitude is then transformed in a geolocated coordinate system that describes the virtual camera attitude on a specific location of our virtual globe.
Finally, we addressed the stereo vision problem. On this work, we have implemented a double pass rendering process that creates an independent image for each eye, that represents the same Earth model from a slightly different perspective. Both images are then presented next to each other, making them compatible with virtual reality sets, such as Oculus Gear, Google Cardboard and similars. In order to create a depth perception to the user, two parallel view directions have been used to render the scene at any moment. This technique, combined with an adjustable “interocular” distance, allows render flawlessly the stereo projection of the virtual earth scenario, and create a real 3D experience to the user at any given scale.
These two new features combined, allow the Glob3 Mobile project to create, in a straightforward way, virtual reality applications. These apps enable the user to explore a 3D virtual earth in first person with his mobile device.