[MUSIC] In this video I would like to compare two different types of content you can have in VR, 360 Video and model Based VR. In order to understand the differences between the two it's probably best if if we first go back to things we're all very familiar with. Let's look at existing digital content we see every day. In general, there are two kinds of digital content, video content and computer generated 3D content. Video content is often shot in the real world with real people. Most news, TV series and movies are produced this way or using a combination of both video content and computer generated content. Computer generated 3D content also sometimes referred to as CGI, or computer generated imagery, can be used to simulate photorealistic real world images, or to portray fantasy worlds with weird creatures. Basically, most Pixar films belong in this category. There's also computer generated 2D content, but this is less relevant to VR, so we will not discuss it here. Let's take a look at a comparison between video content and computer generated 3D content. In video content everything is captured from real life with analog or digital cameras and this information is stored in the format of images or pixels. This creates the kind of content that is highly realistic looking by definition, but capturing it is quite a fast procedure. But the down side is that you are stuck with what you have captured. With computer generated content, you first create and animate the 3D models you need, then you capture those animated 3D models with virtual cameras. So you end up with not only a computer generated images which are captured with you virtual camera, but also, 3-D scenarios which contain all the models and animations you have created and which you can reuse. With computer generated 3D content, you can go beyond real life. You can create fantasy world with weird creatures as you wish. This is a much slower procedure as you have to start from scratch. But once you have created your 3D scenario, you can render your 3D content from a different angle or animate it differently. This is very important in VR, because we can program 3D models to be interactive in real time. And that is exactly what 3D computer games do. Most of them are based on computer generated 3D models where users can never get an environment freely and can interact with animated objects in real time. Nowadays we are very good at creating 3D models and rendering computer generated images. So some of them look photo realistic. For instance in a driving game, it's only obvious that the cars and the environment are computer generated because you have the ability to switch lanes freely and you can overtake cars in front of you any time. This 3D world can be programmed to respond to your actions in real time. So let's now move on to talk about 360 video and model based VR. Model based VR uses computer generated 3D graphics. So in this case, the VR content is based on 3D models, which are files stored with the mathematical descriptions of the geometry and materials. The VR content could also include the descriptions of lighting an animation of these models. With model based VR participants can have the ability to control the virtual camera in real time and look from any point of view. In other words users can move closer to an object to observe it from a shorter distance or when they have a table in front of them, they can change viewpoint to see what's underneath the table. On the other hand, 360 video and imaging or 360 VR as some people call it are based on pre-captured images. So they restrict the user's viewpoint to one specific position or in some videos, to a dynamic viewpoint chosen by the director, not the user. From this fixed viewpoint, users can look left and right, up and down, but they can't freely control movements through the sim and they can't observe objects from any angle or position. 360 video and model based VR are two different types of VR content. Understanding which type of VR content you are dealing with will help you make decisions about which VR display and VR interaction to have. Model based VR is best viewed on a high-end VR display with not only rotation but also position tracking. This way you can benefit from being able to move closer to an object to observe it closely or to bend your body to see what's underneath the table. Position tracking allows users to use their body to observe an object naturally and thus, utilizes the full capacity provided by model based VR. On the other hand, 360 video can be viewed using mobile VR. In this case, the image, or video-based VR content limits how it is displayed. The user's view point is limited to a specific point and position tracking which comes with high end VR displays does not really add anything. When it comes to VR interaction, motor based VR can support real time interaction with VR controllers. For example you can program your scenarios so that you can pick up a 3D object with the VR controllers. But as we know 360 VR content is stored as images rather than 3D objects so 360 video is normally not interactive, at least, not in the same way as model based VR. However, the boundary between 360 and model based VR could blur in the near future because of emerging technologies in areas of computer vision and image-based capturing and rendering. Such methods include light field capture, photogrammetry and volumetric capturing. This is beyond a scope of this course so we will not discuss them here. But if you're interested, take a look at the reading material and video links provided. [MUSIC]
