Interactive shape modeling using functionally defined objects

Abstract

Creating digital models is a complex task in computer graphics. Animation developers usually use two methods. The models are either sculpted from a traditional material such as clay or plasticine, and then the model must be digitized. Models can also be created using one of several commercial (or custom) modeling systems, such as MAYA or SoftImage. Since clay can be molded to create smooth surfaces and precise details, most designers very often use this method. It would be useful to give users the same opportunity as modeling from clay or plasticine, but in virtual space. So that the designer can deform the work piece, add details, and remove unnecessary parts. In addition, virtual shopping malls, virtual worlds, scientific visualization, design, construction, and so on, require huge costs to transmit three-dimensional geometric data over the network. This requires a compact description of three-dimensional objects. Considering these requirements, methods were developed with the following features. Innovations in the interactive modeling interface that take advantage of functional model assignment. This is the orientation and positioning of the sculpting tool relative to the surface. The paper describes the interactive modeling of deformation forms of models based on perturbation functions. Such objects are characterized by a high degree of smoothness and are described by a small number of functions. They are easy to deform and create shapes similar to modeling from plasticine. The proposed method of deformation of the functionally based models with fast visualization allows to provide the interactivity and a realistic appearance of the resulting shapes. An interactive modeling of deformations is presented. The process of interactive modeling of geometric shapes defined by perturbation functions is described. A method for interactive modeling of functionally defined objects without preliminary triangulation is proposed. This allows more accurate definition of 3D shapes and simplifies the modeling system. The algorithm for finding the minimum common parent for the objects, the algorithm for adding an object (perturbation) to the scene, and the algorithm for selecting the objects in the scene were developed for this purpose. A method for visual representation of free forms and analytical perturbations for interactive modeling is developed. An interactive scene editor has been created with the ability to save the result both as a scene file and as a bitmap image. The set of primitives for constructing scenes has also been expanded, and the properties of new primitives have been investigated. When creating the editor, work was done to optimize the rasterization algorithm. A method adapted for graphic processing units is used for rapid rendering of 3D models. The considered scientific problem can be used to facilitate the modeling of 3-dimensional surfaces with different types of deformations, which can be relevant for solving applied problems.