Study On Technology For Three-dimensional Object Modeling And Scene Construction

Three-dimensional object modeling and scene construct is now a research focus. It plays an important role in the virtual reality, games design, digital cities, virtual roaming, GIS and CAD applications. In game design, we should save the mesh data of game scenes and characters generated by the art designer in 3ds max.In the CAD system we should establish model for many object and generate G code to drive the CNC machine tools. In the GIS system, we have to model three-dimensional data for terrain. In virtual reality and game, we want to construct a scene graph, and the scene of three-dimensional objects are composed of polygon collection or spline surfaces, the game character walking paths can also be designed as a spline curve, in the animation, on the various forms of deformation actually is spline surface deformation. As a result of the representation of three-dimensional objects and modeling as well as the construction of three dimensional scene was very important.It provides many methods of object modeling in this article,we also develop a scene constructed platforms and an intersecting lines software development platform. Specific studies include:For a polygon mesh modeling, we design an efficient data structure to save and draw a 3D shape data. We design a mesh data structure that contains the vertex sets, face sets and the normal vector sets, we offer appropriate algorithm to generate these three sets, and provide methods for drawing the Mesh class. For a polygon mesh modeling, surface modeling and CSG (Boolean body) modeling provides unified data structure and mesh files, as well as scenes constructed language, unified scene class design and implementation, and provides modeling algorithm for various objects. Provides an interactive picture extraction contour method, designing a construction algorithm for stretch object, rotating object, smooth surfaces, ruled surface and dual variables explicitly function surface, and writeing it to file.This makes it easy to construct the scene using SCL(Scene Construct Language). This paper deals with a coordinate model and calibration of multi-joint type CMM. A generalized model of pair unit has been proposed,through which the coordinate model of a multi-joint type 3D scanner (MJT3DS) system is easily deduced from. Consequently a new approach for calibration of parameters in the model is presented in the paper. Based on real-valued genetic algorithm,this calibration algorithm has more advantages over than that of linear algorithm by applying least square and iterative algorithm. The feasibility and robustness of this algorithm have been proved through computer simulation.We explored spline surfaces modeling, including Bezier surface and B-spline surfaces, ruled surface and the revoluting surface. We can change the surface shape by moving a control point. Also we use the data structure classes and constructs the mesh vertices sets, face sets and the normal vector sets. It can also be written to the file and makes it easy to construct scene using SCL.We describes CSG body modeling using SCL, Boolean operations and ray tracing technology to enable composite body modeling. We used the ray tracing algorithm, ray tracing class and the classes of Boolean operations. We use SCL to draw the CSG. In order to improve the speed of ray tracing, using a bounding box to accelerate it.We design the classes of the various kinds of scenes and SCL. We provides classes of scenes and SCL to be able to read the 3ds max, vrml and mesh files. Using SCL we can place these files together and provides rendering for them. Take advantage of the SCL we have developed a scene structure of the platform. It allows you to add a 3D object in the scene, transforming and rendering, and write a scene to file.We developed a intersecting line of software platforms. We describes implementation of intersecting software key technology and core classes. By changing the parameters, we can see 2D and 3D graphics, the cutting simulation of graphics, and generating G code to drive the CNC equipment tools.