Hi, welcome to Spinning Up in VR! I am Manorama and this is the sixth of a 9-part tutorial on Virtual Reality (VR) for beginners.
In the previous parts I have talked about the VR Software and HCI in VR and in this chapter, I will introduce the Navigation in Virtual Reality. If you are interested in reading the previous or the next chapters, the links are at the bottom of this article.
One of the most basic VR interactions is the user’s ability to move around and explore the virtual environment. There are different ways you can design navigation in VR depending on what you want the users to do. They might not need to move that much if they’re watching a football match especially if they’re already sitting in the best seat. If they’re doing sports such as playing ping pong in VR then they should be able to use their body as naturally as possible but within a relatively small area this can be simply supported by or if you want to use this to be able to explore a larger space something bigger than the physical space they’re actually in.
- For instance, they might want to walk around and view the space in the 3D model of a house before it’s built. Then you will have to be a bit more creative. We will introduce a few methods for you to consider in this situation. The user’s ability to navigate in VR is also restricted by the VR system they’re using. High-end VR is supported by a desktop or laptop. It usually comes with position tracking of the headset. This allows the users to explore the environment in a natural way as the graphics in the virtual world will just update according to the physical position detected by the tracking system.
- So high-end VR with precision tracking supports physical navigation where the user's physical motion is used to transport a user through the virtual world. With most mobile VR system where the precision tracking is not supported, we’re physically kind of stuck in a fixed point in the virtual world. So we can’t bend our body to see what’s underneath the table and we can’t walk up to an object to observe it up close. In other words, due to the limitation of our tracking devices, certain physical movement cannot be fully captured and translated into the virtual world. But this does not mean that we can’t move in the virtual world. We just need to find other ways to tell our device that we want to move. The most common way of doing this is to borrow what we do when playing games on the 2D screen. Where we normally navigate the environment using a patch pad or a joystick. This is known as virtual navigation. With this method, users are no longer restricted by the physical space they are in and their body remains stationary even though the viewpoint moves.
Few situations that should be taken care of in case a person is navigating in Virtual Reality:
- The most extreme version of virtual navigation is to directly adapt what people have been doing with the 2D game controllers into VR where the users use a joystick or touchpad to control both the direction and the speed of travel. However, in VR, this often causes a strong feeling of nausea. There are two reasons: first, in real life, most of the time we would be looking towards the direction of travelling. So if I use a joystick to define the direction of travelling rather than the actual direction of my hand, it generates a conflict in my sensory system which causes simulation sickness.
- Secondly, this method often produces quite a lot of changes in speed or acceleration which is another factor that has been proven to be a major contributor to simulation sickness. In order to prevent this, the simplest solution is just to use the user’s head direction as the direction of travel at a constant speed. The users should be able to indicate start or stop, or pressing a button, or if there is not a button available, by looking at a particular object.
Few possible ways to deal with movement in Virtual Reality:
- Now, If you have a rotation-tracked controller you can use that to indicate the direction of travel instead of using the user’s head rotation. In order to solve the problem with speed, you can look at other more physically active ways to define speed in real time without using the joystick or touchpad.
- For instance, if you have two VR controllers that are both positions tracked you can use the distance between the two controllers to define speed in real time. So you will expand your arms when you want to travel faster, and hold the two controllers close to each other when you want to travel slower. Again, this generates a variation in speed but because you are more actively engaging your body, it is less likely to cause simulation sickness.
Another way to travel in VR is a method called teleporting. With teleporting, users can travel from one place to another by looking at the new place selecting it and the next moment they’re in a new position. The new place users wish to travel to is often called the target location. In some applications, several target locations are predefined and users can either look at a target or point at one with the controller to indicate which one they wish to travel to.
- However, it is a good idea to try to preserve a user’s current head rotation when bringing the user to the new location. But still, users could feel quite disoriented when they just landed in a new place. In order to reduce the feeling of disorientation, there are several things you can do.
- First, instead of just re-positioning the virtual camera from one frame to the next you could do this over a couple of frames by generating some of the frames in between. So the users feel as if they fly very quickly from one place to another. When doing so, you might wish to make the images from the in-between frames blurry in order to avoid simulation sickness. Second, you can give some visual cues to the user to get her better accustomed to the new position.
In the later chapters, we will look closely into what are the challenges in VR and what are the obstacles need to be overcome in future. Stay tuned!
I hope that anyone who reads the entire series in the given order you will have a clear visualization of VR technology. Please feel free to leave your comments below for feedback. You can find me on Twitter(@mnrmja007), Facebook(@mnrmja007) and Medium(Manorama Jha).