[MUSIC] In real life, we could easily interact with objects within reach, so we should be able to also do this easily in virtual reality. There are several applications in VR which could, in particular, benefit from being able to interact naturally with objects around you. For instance, in most physical rehabilitation applications where patients learn how to regain their motor control. Or other types of training and therapies where it's important to simulate the experience as realistic as possible. Or in sports games where user can have fun catching and throwing a ball quickly and precisely, just like they do in real life. The most naturalistic way to enable object interaction within reach is to use a simple virtual hand to represent the user's real hand. Assuming our hands are tracked with six degree of freedom in VR, the motion of the virtual hand should be a direct mapping of the user's real hand. So we can move our hands and reach out to objects exactly the way we interact with real objects around us. Once the hand overlaps with an object in the 3D space, we can press a button to select the object. And then this object will be attached to our hands, so we can rotate it and bring it to a different position. We can then release the button to release the object at the new location in its new orientation. The whole selection and manipulation procedure is very intuitive, as it directly simulate how we interact with real objects in the real world. So everybody can learn how to do it very quickly, and we don't need to really think about it, so we can focus on other tasks needed in the VR experience. There are different ways you can design the visual representation of the hand, it can be either a human hand, a robot hand, or an abstract hand. Some applications use transparent hands, or human hands with gloves. Depending on your application, it might be a good idea to have something more generic, rather than overly realistic. For instance, you might not want your hand to be too gender and age specific, so that your applications are more suitable for a diversified user group. There are few problems with the simple virtual hand approach, the biggest problem is that users can only interact with objects within reach. If they want to reach something further away, they must first move close to the object, which comes with its own problems and constraints. Secondly, as the interaction is very naturalistic and intuitive, users would also have a high expectations, and might get frustrated when things don't stand up to their expectations. For instance, if there are a few items within reach, but only a subset of them were designed to be interactive, it should be made obvious to the user which items they could interact with. By, for instance, assigning a different color to it. Finally, a problem with object interaction in general is, because those objects don't physically exist, it is impossible to prevent them from going through each other, while also being attached to your hands. If I grab a mug and put it on the physical table, the mug will not go further down where the surface of the table is, and so as my hand holding the mug, unless I let go. But in VR, there is no real physical boundaries stopping my hand from going further down. So when I put a virtual mug on a virtual table, and I insist on dragging the mug underneath the table's surface. The developer will have to choose to either let the mug go through the table, or let the mug detach from my hand. Either will risk breaking the plausibility illusion. [MUSIC]
