• Progress Reporting
• Social Networking/Communication.
The Teacher-Facing App gives the teacher control over the classroom and the ability to monitor, adapt, and modify the curriculum. The structure of lessons must be completely transparent so that the teacher can modify parts of a lesson. As a part of teachers’lesson planning and classroom management they should have access to a dashboard that provides information on any individual student as well as cross-class information about specific topics. The teacher needs to be able to assign different sets of materials to different students.
An important part of the teacher’s ability to modify lessons is a Lesson Planning tool that provides a framework for planning curriculum (calendar, plans for a day including sequencing activities, and differentiation of instruction and materials).
Thus, the Teacher-Facing App provides the teacher with:
• Real-Time Classroom Management
• Lesson Planning/Calendar
• Assessment Tools
• Reporting
• Social Networking/Communication
• Tools for Managing Students and Classes
• Dashboards and Tools to Review Student Progress, Work, and Performance.
6.4.1 Field Of View (FOV) and Field Of Regard (FOR)
Humans have approximately a 180°–200° horizontal field of view, but only approximately 30° in the center of that comprises our highly detailed central vision.
The rest is peripheral vision, which sees much less detail, is less sensitive to color, but ismoresensitive to motion.
The wider the FOV in the VR display, the more realistic and comfortable the experience will be, if other aspects of the display are managed well. It allows the user to spend less time looking around and to see more things in relation to each other. Fortunately, today’s commodity head-mounted displays provide a 90° field of view, which is acceptable. Their main strength is a fully 360°field of regard, which lets the viewer look in any direction. The visual cortex does an excellent job of effortlessly stitching together what the eye sees, as the user looks around, pro- viding a panoramic sense of the virtual world.
Field of View is also important in AR applications, because it limits what you can add to the physical world. When the user of a head-mounted AR display turns their head past the FOV capability of the device, the AR objects disappear, which usually breaks the illusion. Unfortunately, this is true of most MR capable headsets available to the public.
Typically a cave or dome has afield of view at least 180°; this is often wider horizontally and vertically in the case of a dome or a CAVE with the ceiling. They rarely include a projection onto the floor, however, and the user always has a number of stable objects around them to remind them that they are still in the physical world.
6.4.2 Fast View Update for HMDs
As we discuss in the introductory chapter, a head mounted display (HMD) allows the user to look in any direction and see one of three things: a completely virtual reality (VR), a mixed reality (MR), or a panoramicfilm, also known as 360 film.
For this to work, the user’s view must update immediately, with no lag or jitter. The image should be refreshed at 90 frames-per-second or better. Otherwise, it breaks the illusion of being in the virtual space (VR orfilm), or the virtual objects appear to float strangely (MR).
Unfortunately, designers tend to build too much into their VR environments or their AR objects. The temptation to add more geometry, more textures, and more of everything is nearly irresistible. The result is a poor frame rate, which is unac- ceptable. One advantage of 360films is that anything the camera can capture can be represented, with no effect on how quickly the image refreshes.
Interestingly, even the worst dome theaters and CAVEs do not have this limi- tation, because all the pixels in the panoramic view are there to be seen in the single view. The view must only refresh at a minimum of 30 frames per second (fps), as
they would in a typical movie theater. The downside, of course, is that the view is always less than 360, often much less. Similarly, when Mixed Reality (MR) is implemented with projectors that add digital objects to the physical world, they only need 30 fps to look stable, as with any other projection.
6.4.3 Motion Sickness in Virtual Reality
This has always been a major problem for VR applications, and to some extent always will be. It arises from a basic sensory conflict, where some sense report to the brain that the user is moving through the virtual environment while others report that s/he is not moving at all. Cataloguing all the factors is beyond the scope of this article, but the most important ways to reduce motion sickness are (1) fast view update (2) otherwise good quality image (3) minimize use of continuous movement, in favor of jump or teleport, (4) and much more. See Lawson (2014) and Davis, Nesbitt, and Nalivaiko (2014) for more information.
6.4.4 The Registration Problem in Mixed Reality
The hardest thing in Mixed Reality (MR) is called theregistration problem, which refers to making the digital objects apparently stay in one place in relation to the physical world. The device has to somehow be aware of the user’s location and direction of gaze on the real world. Then it redraws the digital object(s) in the correct physical location 90 times per second,4regardless of how quickly the user is looking around and/or moving.
Lower-end AR applications can use a simple camera, like the one on smart- phone, but this is reliable only when it has a high-contrast symbol to lock onto. This supports many useful applications, but is ultimately quite limiting. More advanced tools analyze the geometry of the physical environment, either using the camera or Lidar, infrared, or some other scanning technology. All of these solutions require a great deal of processing power, which makes fast updates difficult. There has been a great improvement recently, with displays such as the Microsoft HoloLens, the Google Tango, and Meta glasses, with many others on the horizon. Nevertheless registration remains a difficult problem and will be an obstacle for some time.
4This standard is somewhat subjective. 90 frames per second is acceptable, today.
6.4.5 Fidelity of Interaction
If the user is expected to interact with the experience, then the application must be extremely responsive, which is challenging in VR and MR. If the device is tracking the user’s body, it must be accurate and precise. The interaction between the body and the virtual objects must also be crisp and accurate. Even when the control devices are “Low-end” or primitive, such as using an Xbox 360 controller to navigate, that interaction must also be responsive and carefully tuned.
Interestingly, users “holding” a virtual tool will tolerate a great deal of indi- rection between their hand and the business end of the tool. It can look completely different from the tracked object they are holding, it can move at a different scale, and it can be oddly shaped. Nevertheless, people are able to use the tool effectively, as long as the interaction is crisp and they can see the results. This is because hand-eye coordination and other capabilities that the brain employs for tool using are very highly developed in humans.