The Automatic Generation Method Of3D Object’s Cross-section Drawn Based On Projecting Plane

Visualization in scientific computing is a hot research direction of graphics. In shortdecades, its theories and application practice get great progress, and it is widely used inarchitectural planning, medical devices, industrial application and so on. In the aspect ofgraphical representation, the use of vector diagram is convenient and effective. Firstly thepaper introduces the characteristics of all kinds of vector data models. Secondlytransformation matrix of parallel projection and perspective projection is derived. Then it putsthe3dt data model expressed as a boundary as a research object. The paper mainlyencompasses two aspects to study. One is the cancel of hidden line and hidden surface of3Dobjects, the other is automatic acquisition of profile map of3D objects.In the aspect of the cancel of hidden line, a kind of algorithm of neutral judgment is used,which firstly divides objects’ hidden line into two classes, and eliminates the first kind ofinvisible hidden line significantly. Then under a given viewpoint, it projects the visible partsof3d objects. Using the bounding box technology, it carries out depth testing and test on theplane, and transforms the problem of blanking into line segment intersection and points’inclusion test. After the calculation of line segment intersection, finally the problem of a3dblanking is transformed into a one-dimensional problem of looking for the union of linesegments. The experimental simulation of the algorithm shows that the algorithm, under agiven viewpoint, can obtain the precise blanking rendering.In the aspect of automatic retrieval of profile map, putting vector graphics expressed as aboundary as the research object, this paper introduces the cutting principle, and expounds theforming process of profile in detail. Firstly, it computing the intersection of entities and acutting plane, and then generates closed contour line by intersecting line, and determines theinclusion relation of contour line. Finally, according to carrying out the triangle subdivision ofthe surrounded area of closed contour line, it generates the entity’s profile. The end of the article implements object’s visual cutting and can simulate realistically cutting effect.