Virtual Reality (VR) is successfully employed for a really huge variety of applications because it can furnish major improvement and can be really effective in fields such as engineering, medicine, design, architecture and construction, education and training, arts, entertainment, business, communication, marketing, military, exploration, and so on.
Therefore great efforts have been paid overtime to the development of more and more realistic and sophisticated VR scenarios and representations.
Since VR is basically a three-dimensional representation of a not real environment, mainly due to computer-generated simulation, Computation and Visualization are the key technologies to pay attention to.
But while Computational Technology experienced exponential growth during the last decades (the number of transistors on an integrated circuit doubles approximately every 18 months according to Moore’s law), the Technology devoted to Visualization did not catch up with its counterpart till now.
This can represent a limit or, even, a problem, due to the fact that human beings largely rely on Visualization, and the human reactions can be more appropriate in front of spatial, three-dimensional images, rather than to the current mainly adopted two-dimensional Visualization of scenarios, text, and sketches.
The current adoption of flat panel monitors which represent only the “illusion” of the depth, does not completely satisfy the requirement of an “immersive” experience.
The requirement for 3D Visualization in VR seems that can be now partially or, in some way, completely satisfied thanks to new possibilities offered by the latest technologies.
We are not thinking to the “standard” 3D representation furnished by flat monitors, but real new 3D Visualization which can occur in a three-dimensional room environment, furnished by dedicated equipment, which allows visualizing any scenario from any perspective.
That’s the way to realize the longed “real” immersive experience, even going beyond mere images visualized on a screen, toward ones that we can interact with and walk-through or navigate-through (the so-called Princess Leia effect from the Star Wars movie) because no solid support for projection is necessary.
Today, the term VR is also used for applications that are not properly “immersive”, since the boundaries of VR definition are within a certain blur degree. So, VR is named also for variations which include mouse-controlled navigation “through” a graphics monitor, maybe with a stereo viewing via active glasses. Apple’s QuickTime VR, for example, uses photographs for the modeling of three-dimensional worlds and provides pseudo look around and walk-through capabilities on a graphics monitor. But this cannot be considered as a real VR experience.
So here we present and discuss new technologies and new trends in Virtual RealityVisualization of 3D Scenarios, also reporting our personal research and applications, especially devoted to new holographic systems of projection.
The actual state of virtual reality
Among all the commonly adopted methods to visualize a virtual or real scenario, there are some technologies worth to be mentioned as the more interesting ones, representing the actual state of new trends. So, in the following the Immersive Video, the Nomadic Video and the Head-Mounted Displays are reported.
Immersive Video (IV) technology stands for 360° video applications, such as the Full-ViewsFull-Circle 360° camera. IV can be projected as multiple images on scalable large screens, such as an immersive dome, and can be streamed so that viewers can look around as if they were at a real scenario.
A different way of visualization comes from the Nomadic Video (NV) approach realized by researchers of the Technische Universität Darmstadt (Huber et al., 2011). The display surface is not required to be dedicated and/or static, and the video content can change upon the surrounding context decided by the user. Everyday objects sojourning in a beam are turned into dedicated projection surfaces and tangible interaction devices.
The approach is based on a pico-projector and on a Kinect sensor (by Microsoft Corporation). Pico-projectors and Kinect capabilities (motion tracking and depth-sensing), might be able to turn any old surface into an interactive display (with varying results of course). Everyday objects, of the real scene surrounding the user, become a sort of “remote control”, in a sense that the pico projector plays different scenes according to their arrangement in the space.
Makeshift display surfaces – a piece of paper or a book, for example – can be manipulated within a limited 3D space and the projected image will reorient itself, even rotating when the paper is rotated. The level of detail displayed by the projector can also be altered dynamically, with respect to the amount of display surface available.
The NV system also allows everyday objects to function as a remote control since, for instance, a presentation can be controlled by manipulating an object within the camera’s field of vision.
The Head Mounted Display (HMD), also known as Helmet Mounted Display, is a visor that can be worn on the user’s head, provided with one or two optical displays in correspondence of one or two eyes.
The possibility to adopt one display for one eye allows different images for the left and right eyes, so to obtain the perception of depth.
The HMD is considered to be the centerpiece for early visions of VR. In fact, the first VR system also highlighted the first HMD.
In 1968, computer science visionary Ivan Sutherland developed an HMD system that immersed the user in a virtual computer graphics world. The system was incredibly forward-thinking and involved binocular rendering, head-tracking (the scene being rendered was driven by changes in the users head position) and a vector rendering system.
The entire system was so cumbersome that the HMD was mounted directly to the ceiling and hung over the user in a somewhat intimidating manner.