Unit 7 Trends in Computer Graphics

5th Semester
BIM Notes

Concept of Virtual reality & simulation
Virtual Reality (VR) is the use of computer graphics and other technologies to create a simulated environment in which the user interacts. A realistic simulation of an environment, including three-dimensional graphics, by a computer system using interactive software and hardware. A computer simulation of a real or imaginary world or scenario, in which a user may interact with simulated objects in real time.  Computer simulations that use 3D graphics and devices such as the data glove to allow the user to interact with the simulation.
A representation of a problem, situation, etc. in mathematical terms, using a computer is called simulation. Mapping the real-world scenarios into mathematical model using computer graphics. E.g.; Robot Operation Simulation, Training.
 
Applications: VR & Simulation

  • Training & Education
  • Entertainment
  • Manufacturing, Planning
  • Data Representation
  • Engineering, and Architectural Design




It refers to any time sequence of visual changes in a picture. Computer animation only refers to moving images. Computer animation is the process used for generating animated images by using computer graphics. Animations often require realism. Animation includes, change in object position, size, color, transparency etc. Animation can also include variations in lighting effects or camera parameters such as position, orientation, and focal length.
In films/advertising often have case of transforming one object in to another.






Changing a can of motor oil into an automobile engine.
Two types of animation

  1. Real-time Animation




Animation which is created and updated in real-time. Such animation allows, for instance, for more realistic virtual environments, such as those encountered in certain multi-user games.

  1. Frame-by-frame animation

Rapidly displaying images, or frames, in a sequence to create the optical illusion of movement.
 Design of animation sequences
In general, animation sequence is designed with the following steps:

    • Storyboard Layout
    • It is an outline of the action, plan; the basic design for animation.
    • It consists rough sketches or basic ideas for motion.
    • Object Definition
    • Object shapes (i.e., polygons or splines) for each objects(characters) in a scene, associated with movements.
    • Key Frame Specification
    • Detailed drawing of the scene at a certain time with every object (character) in a specified position.
    • In-betweens
    • Intermediate frames between key frames. “Stepping stones” between key frames.




 
Computer animation languages
Design and control of animation sequences are handled with a set of animation routines, which are called computer animation languages. Any general purpose language can be used, but several specialized animation languages have been developed.

  • Key Frame Systems
  • Specialized animation languages designed simply to generate the in-betweens from the user-specified key frames.
  • Parameterized Systems
  • Designed to specify object-motion characteristics such as degrees of freedom, motion limitations, and allowable shape changes.
  • Scripting Systems
    • Scripting systems allow object specifications and animation sequences to be defined with a user-input script.
    • From the script, a library of various objects and motions can be constructed.




Morphing and simulating accelerations.
Morphing
It is derived from the word metamorphosis, which means the transformation shape, appearance of one thing into another. The transformation of object shapes from one form to another is called morphing.
Also it can be defined as:

  • Transition from one object to another.
  • Process of transforming one image into another.

 Simulating Accelerations

  • For speed (zero acceleration), we use equal-interval time spacing for the in-betweens.
  • But when we need unequal time-interval spacing, simulating acceleration is used.
  • Method for adjusting unequal time spacing for the in-betweens.
  • If there are n in-betweens separating key frame k (at time tk)
  • and key frame k+1 (at time tk+1) then the time spent on each in-between is

∆t = (tk+1– tk)/(n+1)

  • Then in-between Bj occurs at time tBj = t1 + j∆t, j = 1, 2, 3, ……, n.
  • Non-zero accelerations are used to produce realistic displays of speed changes, particularly at the beginning and end of a motion sequence.