For discrimination of the common W-junction and Y-junction in the labels of line drawing for a three-dimensional manifold plane surface with trihedral vertices, the existing algorithms are almost using angles between ...For discrimination of the common W-junction and Y-junction in the labels of line drawing for a three-dimensional manifold plane surface with trihedral vertices, the existing algorithms are almost using angles between two adjacent lines and W-junction and Y- junction＇s definitions, and other complex methods. This passage gives four methods with their detailed mathematical inference processes in order to use these algorithms implemented by computer. The algorithms listed are Angle Summation method and Points to the Line method, Triangle methods which are the Triangle Area method and the Cross method. When the computer programs discriminate junctions, by comparison, the Angle Summation method and Points to the Line method are less efficacious than the Triangle method, and Cross method is more efficacious than the Triangle Area method in the Triangle method.展开更多
Although line drawings consist of only line segments on a plane, they convey much information about the three-dimensional object structures. For a computer interpreting line drawings, some intelligent mechanism is req...Although line drawings consist of only line segments on a plane, they convey much information about the three-dimensional object structures. For a computer interpreting line drawings, some intelligent mechanism is required to extract three-dimensional information from the two-dimensional line drawings. In this paper, a new labeling theory and method are proposed for the two-dimensional line drawing with hidden-part-draw of a three-dimensional planar object with trihedral vertices. Some rules for labeling line drawing are established. There are 24 kinds of possible junctions for line drawing with hidden-part-draw, in which there are 8 possible Y and 16 W junctions. The three problems are solved that Sugihara＇s line drawing labeling technique exists. By analyzing the projections of the holes in manifold planar object, we have put forward a labeling method for the line drawing. Our labeling theory and method can discriminate between correct and incorrect hidden-part-draw natural line drawings. The hidden-part-draw natural line drawings can be labeled correctly by our labeling theory and method, whereas the labeling theory of Sugihara can only label the hidden-part-draw unnatural line drawings in which some visible lines must be drawn as hidden lines, and some invisible lines must be drawn as continuous lines.展开更多
文摘For discrimination of the common W-junction and Y-junction in the labels of line drawing for a three-dimensional manifold plane surface with trihedral vertices, the existing algorithms are almost using angles between two adjacent lines and W-junction and Y- junction＇s definitions, and other complex methods. This passage gives four methods with their detailed mathematical inference processes in order to use these algorithms implemented by computer. The algorithms listed are Angle Summation method and Points to the Line method, Triangle methods which are the Triangle Area method and the Cross method. When the computer programs discriminate junctions, by comparison, the Angle Summation method and Points to the Line method are less efficacious than the Triangle method, and Cross method is more efficacious than the Triangle Area method in the Triangle method.
文摘Although line drawings consist of only line segments on a plane, they convey much information about the three-dimensional object structures. For a computer interpreting line drawings, some intelligent mechanism is required to extract three-dimensional information from the two-dimensional line drawings. In this paper, a new labeling theory and method are proposed for the two-dimensional line drawing with hidden-part-draw of a three-dimensional planar object with trihedral vertices. Some rules for labeling line drawing are established. There are 24 kinds of possible junctions for line drawing with hidden-part-draw, in which there are 8 possible Y and 16 W junctions. The three problems are solved that Sugihara＇s line drawing labeling technique exists. By analyzing the projections of the holes in manifold planar object, we have put forward a labeling method for the line drawing. Our labeling theory and method can discriminate between correct and incorrect hidden-part-draw natural line drawings. The hidden-part-draw natural line drawings can be labeled correctly by our labeling theory and method, whereas the labeling theory of Sugihara can only label the hidden-part-draw unnatural line drawings in which some visible lines must be drawn as hidden lines, and some invisible lines must be drawn as continuous lines.
