IT: navigation

article 0: Go through this powerpoint to get a quick overview of the material below.

Travel is movement in and around an environment, it’s the motor component of navigation. In the real world, it’s the physical navigation task, such as moving feet, turning a steering wheel, turning around etcetera. In the virtual world, the used can translate or rotate the viewpoint and modify the conditions of movement, such as the velocity.

User tasks for Travel

1. Exploration

The user has no specific goal for any of the movement that is performed. It is browsing the environment, obtaining information about the objects and locations within the world and building up knowledge of the space.

In order to design for this type of task, it is important to provide freedom to the user for moving around in space. It is possible to insert cues and triggers, but these need to be minimal. Also, it is important to reduce the cognitive load, so that the user can focus on spatial knowledge acquisition, information gathering and other primary tasks.

2. Search

In a search, the user will have a specific goal or target to navigate to. However, he doesn’t have to know where the exact location is. You can make a difference between a naive search task (target position = unknown) and a primed search task (target position is known)

3. Manoeuvring

Manoeuvring tasks take place in a local area and involve small, precise movements. This task can be necessary when the user needs to read something, or needs to take a closer look at an object. (Have a look at the basement in VRENZ’ Bartiméus experience - S2 2017-2018. All those “crowding” tasks!) These movements are small-scale and can take up quite some time (and frustration) from the user.

Other Travel Characteristics

• Distance, what’s the range, does it need velocity in order to provide a continuous flow?

• Amount of turns and curvatures in the experience.

• Visibility of the target at starting location

• Degrees of Freedom needed for the movements.

• Required accuracy of the movement.

• Other primary tasks that take place parallel to the navigation task.

Travel Techniques

• Active versus Passive: does the user control the movement continuously or is it done by the system?

• Physical versus Virtual: what’s the balance between the physical movement and the virtual movement?

• Using Task Decomposition: how does the user travel? (the selection of direction, velocity and input conditions)

Bowman taxonomy

Fig. Taxonomy of Travel Techniques (Bowman et al, 1997 © 1997 IEEE)

Travel Techniques by Metaphor

1. Physical locomotion metaphors (Walking, Cycles, Treadmills etc.)

2. Steering metaphor

3. Target specification & Route planning metaphor

4. Manipulation Metaphor

5. Scaling Metaphor

1. Walking technique in Virtual Reality

• Real walking: VR has limited options, but for AR mobile apps, this is something to explore.

• Redirected Walking can be used to create unlimited corridors and infinite stairs. Use with caution!

• Scaled Walking: e.g. Seven League Boots Locomotion Technique: scaled walking approach by walking slow or uptempo.

• Walk-in-Place: compromise, the sense of presence and real movement is diminished, low immersion.

• Human Joystick: the user will move on a sensor-based platform in reality in order to navigate.

• Human Joystick (other): the environment changes slightly while playing the game.

• Treadmill walking and Running

• Teleporting: most common used method to navigate in VR.

link

Example of Redirected Walking

2. Steering in Virtual Reality

• Gaze-directed Steering. Can be extended by motion and give the user the ability to strafe - go up, down, move backward and go left and right. Simple HMD's, such as Google Cardboard can be used. Problem is that the user needs to navigate and gaze in the same direction.

• Hand-directed Steering (pointing). The user's hand (tracked controller) specifies the direction. Another option is to let two hands define the vector for a navigation direction.

• Grabbing the Air Technique: like pulling a rope in the air.

• Move Tour Own Body: Torso-directed Steering. and Lean-directed Steering. People naturally turn their bodies towards the direction that they are taking. With Lean-directed steering the user does not take any steps, but leans towards the direction he wants.

Click on the image. PenguFly is a bimanual body-directed travel technique for virtual environments. To travel, the user moves her tracked hands and head relative to each other.

3. Target/Route Selection

Target-Based Travel Techniques

• Representation-based Target Technique: moving the avatar's position on a 2D-map and then the avatar will walk to this position in 3D.

• Dual Target Techniques

Route-planning Travel Techniques

• Drawing the desired path.

• Marking points along a path.

4. Manipulation Metaphor

• Viewpoint manipulations: camera (in hand technique), avatar (world-in-miniature) and fixed-object manipulation (viewpoint moves relative to the fixed object).

5. Scaling Metaphor

• Active scaling: user takes active control in the scaling of the virtual world.

• Automated scaling: multiscale virtual environments, in where the system takes over sometimes, in order for users to stay focused on the right task.

Locomotion in Virtual Reality

In VR, the concept of standard locomotion controls is turned on its head. Most of the time, traditional game controls don’t work well in virtual reality games. Lateral movement with a thumbstick or a keyboard can trigger motion sickness in a lot of people. Your inner ear controls your sense of balance and spatial awareness (vestibular system), if what your inner ear perceives is different from what your eyes perceive (vestibular mismatch) you can lose your balance or get dizzy. A vestibular mismatch can even trigger nausea or vomiting in extreme cases.

VR Locomotion Methods

Rope Based Locomotion

source: thesis: vive & rope based locomotion by Nicholas Dorbin

19 locomotion methods

The following locomotion methods can be distinguished: (source tom's hardware) 1. Smooth Artificial Locomotion is the movement system that traditional gamers are most familiar with. It involves using a trackpad or thumbstick to navigate through virtual worlds as you would in a traditional console game.(VR game: Onward)

• Dynamic FOV Reduction: dynamically reducing the field of view while moving in VR dramatically reduces the likelihood of triggering motion sickness. This method is best paired with a smooth artificial locomotion system. (VR game: VR Apocalypse)

• On-Rails Locomotion: the developer paced the action by spreading it across multiple partially scripted scenes, which gives it somewhat of a wave shooter feel. Between action sequences, the mech moves forward, but you don’t get to control where it goes. (VR game: Archangel)

• Physical Movement – Planted: locomotion system that is all about physical movement. You can’t just stand up straight and expect to win a round of this game. You must duck behind cover and keep your head down if you wish to survive. (VR game: Front Defense)

• Physical Movement – Active: doesn’t include an artificial locomotion system. It relies on physical movement to get around and the locomotion is emphasized on rapid, active movements (VR game: Space Pirate Trainer)

• Instant Teleportation: this is the most basic form of VR teleportation. As the name would suggest, with this locomotion system, your movements from space to space are instantaneous. It doesn’t include a special animation to explain the movement. With this method, you point to where you want to go, and when you activate the movement button, you’ll be where you were pointing in the blink of an eye. (VR game: Vanishing Realms)

• Teleport - Blink: to move, press the thumbstick or trackpad forward, which will activate a reticle that you can place within a set radius from where you are. You can also rotate the thumbstick or your thumb on the trackpad to change your orientation while you move. The name "blink" comes from the way the scene “blinks” away in blackness momentarily as you move to your new location.(VR game: The Gallery: Call of the Starseed)

• Teleport Dash: Dash is a better teleport mechanic for the close-quarters combat that Raw Data offers. The Dash system offers a button-activated reticle that you use to point to your next location, but instead of fading out the scene and then presenting the new location when the scene fades in again, you move to the new location at an ultra-fast pace. This allows you to retain a connection with your surroundings as you move. (VR game: Raw Data)

• Teleport Sprint: The Sprint teleport mechanic is a lot like Survios’ Teleport Dash system in that you can use the reticle to pick a spot to move to and then watch the world accelerate around you. But Cloudgate Studio added a stamina system to its movement mechanic, which is supposed to simulate the idea of running through the jungle. You can only run so far before you need to stop and catch your breath. (VR game: Island 359)

• Teleport – Projected Avatar: With this teleport method, you still use a reticule to point out where you would like to move. However, instead of moving directly there, or rushing through the environment to the next location, you get to see a virtual avatar of yourself moving through the area before you decide where you wish to go next. You still teleport to the selected location, but the animation of the avatar allows you to understand the route you took to get there. It also gives a better explanation of why you can’t teleport past immovable objects, or over a balcony to the ground below. (VR game: From Other Sounds)

• Thrown Object Teleporter: You get a throwable object that teleports you to where it lands. Tossing an object isn’t as accurate as pointing a reticle with your motion controller, but it offers movements that aren’t possible with a reticle, such as tossing the object against a wall to bank it around a blind corner. (VR game: Spells 'n' Stuff)

• Teleport – Preview Cam: unlike the Thrown Object Teleporter, Budget Cuts’ portal gun offers a preview camera that lets you see the surroundings before moving to the new location, and nothing is stopping you from taking another shot if the landing zone is undesirable. (VR game: Budget Cuts)

• Host to Host Teleportation: The game features a somewhat parasitic movement system in which you take control of different host bodies to move from place to place. When you’ve exhausted your current hosted body’s usefulness, move on to the next one to continue your journey. (VR game: Damaged Core)

• Armswinger is a natural-feeling solution for traversing long distances in VR. To move, press a button on your controller and then swing your arms at your sides like you would when you run. The faster you swing your arms, the faster you’ll move in-game. (VR game: Vindicta)

• Tunnelling locomotion system limits the feeling of movement by confining the moving animation to a focused part of your view. You navigate to the new location within the small window, while the environment around you remains stationary. When there’s no motion in the inner scene, the world around you morphs into the new location. (VR game: no game, only demo)

• Head-Bobbing Locomotion is another movement system that takes advantage of a somewhat natural movement derived from walking or running. When you walk or run, your head naturally bobs up and down. It leaves both your hands free to handle weapons and items. You can activate the motion by bobbing your head up and down, or by running in place. (VR game: Evasion)

• Walkabout Locomotion allows you to pace back and forth within your physical space while continuing a straight path in the game. When you reach the limitation of your room-scale play area, press a button on the controller to “freeze” the world around you, so that you can turn around without changing directions in the game.

• Redirected Walking

• Superman Locomotion: Old Leap Motion version. Hold out your hands in front of you to move forward, and point your hands in the direction you wish to fly the virtual environment. (VR game: Weightless)

Weightless