Interactive Sketch Interpreter for Geometric Modeling

Abstract

CAD software and similar modeling systems can show 3D object models created by designers, but these advanced 3D systems demand precise data about the 3D object, especially in the steps of inputting data and making free-form surfaces. Although it has become common to use CAD/CAM systems to increase the efficiency of the industrial design process, traditional sketching is often more efficient in the early stages of concept design. Since it is difficult to design a CAD system which can create 3D objects from a concept sketch directly due to ambiguous information, recently sketch systems have been introduced to bridge the gap between concept design and computer-based modeling programs, combining some of the features of a pencil-and-paper sketch. It has now become a big area of research of increasing the flexibility of 3D data input techniques for CAD systems. Concept Sketch is a concept design process for the designer. It is used to draw contours of products on paper by pencil step by step. In order to get 3D shapes, it is required to recognize these shapes from the concept sketch. Designers can not use or feel very uncomfortable to use these systems for realizing their idea sketches. This survey paper deals with a freehand sketch based geometric modeling for constructing complex 3D objects. In this talk, many useful sketch systems and methods are classified. The following sketch systems are shown: (1) A sketch-based modeling system based on descriptive geometry is proposed to make a model of a variety of 3D solid objects and surface objects. The main goal of sketch-based systems is to allow the creation of 3D models by using strokes extracted from user input and/or existing drawing scans. (2) The contour line method to propose a sketch interpreter system for designing 3D freeform objects. The essential idea is the use of freeform stroke as an expressive design tool. The Freeform stroke is classified into three types: outline (contour line), shading line and cross section line. The outline with shading lines are used to generate the basic rounded 3D shapes. The shading lines and cross section lines are used as control lines which are drawn inside the contour for modifying the basic 3D shape. (3) A method using a template topology library as an essential tool to reconstruct and modify 3D objects with sketch lines. 3D objects can be generated in a basic 3D shape reconstruction procedure, or modified in a 3D shape modification procedure. (4) A Sketch modeling of Implicit Surfaces by using cutting method and three orthographic views. We developed a cutting method using implicit surfaces based on a Cube. Characteristic point is blending function compare with our three proposed sketches interpreter system. (5) Digital sculpting with history management of strokes. This is a new digital sculpting system based on the history of stroke input. In these systems we are interested in interpretation, where the computer creates the 3D objects step by step. The designer can feel more comfortable to quickly evaluate their ideas for designing a new object compared with the traditional CAD system.