cgvr ppt key frame animation computer .

computer graphics

1. KEY FRAME ANIMATION

2. A key frame in animation and filmmaking is a drawing that defines the starting and ending of any smooth transition. These drawings are called frames because their position in time is mentioned in frames on a strip of film.

3. A key frame animation consists of an automatic generation of the intermediate frames based on a set of key frames, supplied by an animator.

4. FUNDAMENTAL APPROACHES In-betweens obtained by shape interpolation Interpolation of parameters of the model

5. CONSTRUCTION OF AN ANIMATION SEQUENCE

6. Animation Sequence STORYLINE OBJECT DEFINITION KEY FRAME SPECIFICATION TWINING

7. STORYLINE Sketch out of the action defining the motion progression as a set of basic events that must take place. Comprises of all the events in a story, particularly rendered towards the achievement of some particular artistic or emotional effects. Could consist of a set of rough sketches or a list of basic ideas for the motion.

8. OBJECT A participant in action – can have some properties and bear relations to other objects. Object definition is given to each participant in action defined in terms of basic shapes. These are coupled with movements of each object in the story.

9. KEY FRAME SPECIFICATION A sequence of key frames defines which movement will be seen. Position of frames in the animation defines timing of the movement.

10. TWINING aka “in- betweening ”. Process of generating intermediate frames between two images. Gives an appearance of the first image smoothly evolving into the second image.

11. Video shown in class

12. Motion Control Methods Methods based on geometric information Methods based on physical information Methods based on behavioural information

13. Methods based on geometric information It is of 3 types performance animation, key frame and image morphing. Performance animation consists of magnetic or optical measurement and recording of direct action of real person. In key frame tech the animator specifies key frame value which are interpolated by computer. Image morphing is warping based tech that interpolates features between 2 images.

14. Methods based on physical information In this animator provides data and the motion is obtain by solving dynamics equations. We may distinguish methods based on parameter adjustment and constraint based, where animator states in term of constraint and properties the model without needing to adjust parameters. Example:- space time constraint may be used to create char animation by solving constrained optimization.

15. Methods based on behavioural information This method drive behaviour of autonomous creatures by providing high-level directives that indicates specific behaviour without any other stimulus. Example:- Distributed behaviour model to stimulate flocks of birds and fish System based on a network of sensors and effectors

16. PROCEDURAL ANIMATION Roll No. : 4

17. KEY FRAME ANIMATION V/S PROCEDURAL ANIMATION Roll No. : 4

18. INTRODUCTION TO MORPHING

19. What do you mean by Morphing? Transformation of object from one form to another is called Morphing. Morphing can be applied to any motion or transition involving a charge. Most of the times, the shapes we morph from and to must have the same number and orientation of vertices , due to this the program knows exactly where each vertex being animated starts and ends. Objects will not be converted into target object . Intermediate targets are created to prevents parts of mesh from collapsing.

20. PROCESS

21. Firstly, interpolate the coordinates of the end points of every pair of lines .(interpolate : insert). Secondly, we warp the deformation of source image towards needed frame. Warping is the process of digitally manipulating an image such that the shape of the image is distorted. This deformation is a pixel by pixel deformation. Also based on reverse mapping . . Let’s see the procedure..

22. Attribute transformation : attributes of one object transformed to another. Topology preservation : preserving topology of the source object during transformation. Monotonicity : changing volume of objects or parts monotonically Feature preservation : features of one object transformed to another. Morphing does not preserve original object. Non-linearity : Linearity needs to be avoided by morphing transformation. Principles of Morphing

23. Slow in and slow out : warping of the object shape evolves linearly but the gray scale transformation does not evolve. Its starts slowly and end slowly. Rigidity preservation : Volume of the source object is preserved by the morphing transformation if the shapes of the objects are isometric. Avoid morphing leakage : Deformation to object will deform the space. Some methods to be used to avoid such leakages

24. WARPING

25. Warping Image warping is the process of digitally manipulating an image such that any shapes portrayed in the image have been significantly distorted. Warping may be used for correcting image distortion as well as for creative purposes.

26. Example of Warping Before Warp After Warp

27. Types of warping techniques Mesh Image Warping. Feature Based Image Warping. Thin Plate Spline Image Warping.

28. Mesh Warping This is an algorithm formed in two steps that accepts a source image and two 2D arrays of coordinates S and D . The S coordinates represent the control pixels in the source image, and the D coordinates are the locations where the S coordinates will match. The final image is the initial image warped by means of mesh S and mesh D .

29. Mesh Warping 1 2 3 4

30. Use in Animation

31. Final Image

32. 3D morphing What is 3D morphing ? A 3D model of the object is transformed from one shape into another. Why 3D morphing ? Morphs are independent of viewing and lighting parameters. View-dependent effects possible e.g., shadows, highlights, camera can be animated during the morph. Traditional 2D morphs are inherently “flat” looking. Features of a Good 3D morphing algorithm Conceptually Simple Minimal topological restrictions. Easy to use user-control

33. Basically, when we refer to 3D objects, we represent them polyhedrally , i.e. by vertices, straight edges and faces each consisting of planer vertex set with the connecting edges. Producing a 3D morphing sequence involves interpolating the inputs so that a polyhedron sequence results, in which every polyhedron looks like the end polyhedron and less like the beginning. The figure on the next slide gives a clear overview of the 3D morphing technique.

34. Overview

35. 3D model Model Polygons (triangles) vertices Other parameters (normals, textures)