3D environments are computer representation of fictional or non fictional worlds. Immersive environments provide tools for users to be completely surrounded and immersed in the environment. Interactive environments instead are "general-purpose hardware for interaction, that is, mouse and keyboard as well as multi-touch input (Jankowski, J. and Hachet, M., 2015)". Good interaction in an interactive environment can be defined by 3 universal interactive tasks:
NAVIGATION: allowing users to interact with the environment, by moving around and explore. Includes a motor component called travel, and a cognitive one, known as wayfinding (a form of interaction with the environment as well)
SELECTION/ MANIPULATION: allowing the user to interact with the environment by grabbing and handling objects found along the way. "Refers to techniques of choosing an object and specifying its position, orientation and scale (Jankowski, J. and Hachet, M., 2015)"
SYSTEM CONTROL: providing users with an effective user interface for users to interact with the environment, and let the system respond to users' actions. Refers to good communication user-system
Image-based rendering (IBR)
Some 3D environment are created through computer algorithms and collection of pictures. Computer mixes together a range of 2D images and builds up an environment by combining various parts and pieces taken from each image.
NAVIGATION:
The process of getting around a virtual environment while keeping track of one's whereabouts and task objectives is the subject of a number of techniques often referred to as camera/viewpoint control, navigation, wayfinding, locomotion.
CAMERA / VIEWPORT CONTROL:
CAMERA/ VIEWPORT CONTROL (point of view of the environment from users' perspective):
allows 6 degrees of freedom: 3 dimensions for translation / position placement in the environment along the 3 axis + 3 dimensions for rotation / angular placement around the same spots
Mackinlay et al. propose 4 types of general viewport moving techniques to INTERACT WITH THE ENVIRONMENT:
ROTATE-PAN-DOLLY: 3 main operations:
ROTATE/tumble/sweep (moving the camera around a main central point, eg: a 3D model, to inspect its various sides, keeping the view focused on the main central point) + DOLLY (translating the camera on the x or y axis) + PAN (translation of the camera on its line of sight / z axis)
SCREEN- SPACE METHODS: techniques for manipulating 3D object from 3 or more touch/contact points. (works also with 2 or more contact points for 2D images). Each contact point defines a constraint which ensures the screen-space projection of the object-space point ‘touched' always remains underneath the user's fingertip. Multi-finger touch points can work for both unimanual and bimanual control.
WALKING / DRIVING / FLYING / SWIMMING: requires users to continually adjust their camera positioning (arrow keys or controls (button widgets) superimposed on the screen and controlled by the mouse). Allows FPP, first person perspective, for a first person navigation of the environment, where a graphical perspective is rendered from the viewpoint of the character. The most notable game genre to use this FPP navigation view, are shooting games (FPS, first person shooting).
With the increase of touch screen for game interaction, Kim et al. introduce a Finger Walking in Place (FWIP), that allows users to walk their character in many directions by simply sliding their finger on the screen. (works for both immersive and interactive environments).
NAVIGATION INTERACTIVE TECHNIQUES
Point of Interest (POI) Logarithmic view:
Players can click on their point of interest of an object and the camera moves logarithmically. Due of the logarithmic nature of this navigation technique, rapid motion is achieved when the distance to the target object is large and controlled movement is achieved as this distance gets shorter. (end point of the camera is target point that the player clicked on). Can be useful in allowing the player to navigate smoothly and seamlessly between local and global views (sky and object, object and ground). The authors suggest that this allows the user to acquire landmark, procedural and survey knowledge and to effectively perform exploration and search tasks. The device automatically estimate how the viewpoint is oriented (whether it is pointing towards the landscape or an object, and adjusts the view accordingly, to zoom in on that target).
WALKING / DRIVING / FLYING / SWIMMING
Path drawing: Walkthrough technique: for navigating 3D interactive environments, extension of POI. User drawn lines show the users' preferred path to navigate the environment and control the camera. A stroke is projected onto the walking surface and used as a path for the camera. Suitable for pen based systems.
Hyperlinks and bookmarked views: keeping track of the users' saved and bookmarked views can be useful when switching between location in the VE which are located far away from each other and would require too much time for the character to physically get there. However, one negative effect is that instant changes can cause disorientation. Some interfaces offer a menu or list of bookmarked camera views. Can offer a choice of viewpoints, usually denoted by a brief textual description that helps make clear the intended purpose of each view.
Navigation by query
Multi modal interaction
b. WAYFINDING:
related to how people build up an understanding (mental model) of a virtual environment and it is significantly affected by technological constraints among which are small field of view and the lack of vestibular information. The least a good wayfinding design can do is allow users not to get lost in the environment
REFERENCES:
Jankowski, J. and Hachet, M., 2015, February. Advances in interaction with 3D environments. In Computer Graphics Forum (Vol. 34, No. 1, pp. 152-190).
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