Anatomy increases the sensitivity of the artist's eye and makes the skin transparent; it allows the artist to grasp the true form of the surface contours of the body because he knows the parts that lie hidden beneath a veil of flesh."Gerdy

Techniques that transform one two-dimensionaf image into another have gained widespread use m recent yeara.Extending these techniques to transform pairs of 3D objects, as opposed to 2D images of the objects, providea several advsntagea, including the ability to snimate the objects independently of the transformation.This paper presents an algorithm for computing such transformations.The algorithm merges the topological structures of a pair of 3D polyhedral models into a common vertex/edgeJface network.This allows trsmsformations from one object to the other to be easily computed by interpolating between corresponding v@ex positions.

Abstract We develop and present a new approach to modelling the characteristics of human hair, considering not only its structure, but also the control of its motion and a technique for rendering it in a realistic form. The approach includes a system for interactively defining the global positioning of the strands of hair on the head. Special attention is paid to the self shadowing of the hair. A mass/spring/hinge system is used to control a single strand's position and orientation. We demonstrate that this approach results in a believable rendition of the hair and its dynamics.

There are several successful systems that provide algorithms that allow for the intersection of polygonal objects or other primitive shapes to create more complex objects. Our intent is to provide similar algorithms for intersecting surface patches. There have been contributions to this concept at the display algorithm level, that is, computing the intersection at the time the frame is generated. In an animation environment, however, it becomes important to incorporate the intersection in the data generation routines, in order that those parts of the intersected object that never contribute to an image are not processed by the display algorithm. This only increases the complexity of the object unnecessarily, and subsequently puts an additional burden on the display algorithms.An algorithm is described which uses a modified Catmull recursive subdivision scheme to find the space curve which is the intersection of two bicubic patches. An associated data structure is discussed which incorporates this curve of intersection in the patch description in a way suitable for efficient display of the intersected object. Sample output of these intersections are shown which serve to illustrate the capabilities and limitations of the described procedures.

A method for generating arbitrary terrain models, including trees, bushes, mountains, and buildings, is described. Procedure models are used to combine fundamental data elements in the creation of unified objects comprising the terrain model. As an example, a procedure model to generate arbitrary trees of various species is implementation. These are the generation of the low level data elements, specification of input parameter requirements, and a brief explanation of the algorithmic structure. Terrain images rendered by this process are included, as are diagrams and illustrations explaining the procedure model organization. Comparisons with previous work are made.

A computer animation system is discussed which employs interactive techniques and presents a unified approach to the graphical display of complex three dimensional data. The system facilitates the generation, manipulation and display of highly detailed data with the aid of interactive devices and a video interface to a standard color TV monitor. The system enables the animator to create a variety of objects (including texture) and to specify the necessary transformations for animation sequences. A run length processing technique combined with a brute force Z-buffer algorithm has been newly designed and implemented that can handle the intersection of several million faces, lines and points. This makes possible a full range of visual cues to simulate fire, smoke, water and complex 3-D texture such as grass, hair and bark. Basic concepts and approaches are described. The display algorithm and the procedure model to generate texture are presented and the implications of the system for computer animation are discussed. Extensions to the system are outlined which include a unique graphics display processor currently under construction that includes a partial implementation of the display algorithm in hardware.