Research On Flatting Technology For 3-D Basic Body Surface

The technology for surface flattening is the important part of the converse projects. It is such work that the 2-D drawing is made through measuring the 3-D object. The technology has made the new products be researched, produced and becoming prototype more rapidly and expediently. It is widely used many fields such as aviation, mechanism, light industry, domestic wiring, car and toy design. The body and garment surface as the very complex 3-D surface are more difficult to be studied in the field of 3-D garment CAD. To flatten such surface by intelligent algorithm and realize the automatic intelligent pattern making are the studying hotspot and nodus for many academician.Now in the researching for 3-D surface flattening, the research for rigid surface as mechanism and aviation appliance is much, and they are also flattened intelligently. The study for body and garment surface is done from the angle of mechanism and automatics. The research is less that combined with the clothing specialty acknowledge and body feature. That leads to the bad practicability for flattened surface. The minimum of area changing fore-and-after the surface being flattened and the speed are paid more attention to. At the same time more research for body surface is to define the surface by the method of surface imitation. The imitation degree is not high is the exited problem. Another problem is some research only have the simple area dividing for the surface and a kind of accurate definition form for the body surface is not formed.According to the present researching condition, the article takes standard female model as studying object and a kind of new 3-D measurement and surface gridding method is brought forward which based on body feature points and lines. To calculate the discrete gauss curvature of the nodes on the surface the formula is given. Then basing on ant colony algorithm a more accurate mathematics definition forms for complex 3-D body surface is put forward. A new surface flattening algorithm is designed which combined with geometry and physics and based on Hook Law. Finally combining with clothing pattern-making and technical shrink and stretch principles, all kinds of surface with different dividing lines are flattened by designing physical amending algorithm. Using the flattened pattern to cut fabrics and sewing them into body surface, which is used to evaluate and test the efficiency of the algorithm. The major researching content and innovation are as following:1) The researching of data acquirement techniques for 3-D surface on body features.A kind of new 3-D surface data acquirement methods is put forward which based on body features. Some key points and lines that play the major role on the body are used to the data acquirement techniques of garment surface. The points and lines are designed and selected. These are also used to the surface gridding techniques. In order to triangulate the measured nodes the method based on surface featured points and lines is lodged and used. The gridding surface of body and the topology information of each node are got. Basing on the data visiting features, the 4-D bidirectional link list is designed as data memory mode. All those are verified to be very effective for the improvement of flattened pattern.2) The definition for 3-D body surface on discrete gauss curvature.A kind of new triangled model is set based on the Gauss Curvature theory from differential geometry and Guass-Bonnet theorem. Express the nodes as vertex and triangle muster by linear list. The calculation formula is given for normal vector of triangles. According to the model the algorithm is designed to calculate the discrete gauss curvature for each node. A evaluating value is set by test. All nodes are classified into two types as developed ones and undeveloped ones by comparing absolute value of gauss curvature for each node with the evaluating value.3) The research of intelligent partition technique for body surface.Apply the ant-colony optimization algorithm to surface partition. The partition for surface is defined as TSP that the optimizing path is found passing through nodes. Take average percentage of nodes as evaluating target function to determine whether the searching will end. A mathematics model is set. Such parameters as pheromones, updating probability and heuristic information are set by test according to actual problem. The astringency of algorithm is also analyzed and proved. The surface is divided into developed area and undeveloped one. The partition line is found also. Finally some papers are placed onto the body to verify the algorithm efficiency.4) The research of intelligent flattening algorithm for undeveloped surface. The new flattened algorithm for undeveloped surface is put forward. The algorithm is based on feature points and lines. It also combines geometric with physics. The algorithm firstly flattens the surface along feature points and lines according to geometric principles. Then a kind of new energy evaluating model is set up based on Hook Law. Using the model the geometric flattened result is amended. It is a kind of physical method. In order to deal with the problem of energy release during surface flattening, the position of dividing lines is analyzed and such two kinds of definition as functional partition lines and nonfunctional partition lines are brought forward. The flattening algorithm that releases the energy along functional partition lines is designed. By comparing the algorithm of this article with the correlative ones it can be got that the algorithm of this article not only make sure that the material's basic longitude and latitude but also make sure that the minimum accumulated energy and regular pattern shape.5) The researching of surface flattening algorithm basing on dart transfer principles and clothing shrunk and stretched by ironing.For the body surface with all kinds of partition lines, different energy release algorithm is designed basing on dart transfer principles. In the algorithm the nonfunctional partition lines are transferred into functional partition lines. In order to realize those transferences the assistant lines are designed. The shortest path searching algorithm is put forward for the designing of assistant lines. The flattened result with partition lines type transferring is compared with that without partition lines type transferring. Such conclusion can be drawn that the new algorithm can effectively reduce energy accumulation and improve the pattern stability. In order to improve flattened pattern stability, an evaluating model for valuating material's shrink and stretch deformable capacity is set up. Such fabrics with minimum shrink and stretch deformable capacity is selected to evaluate flattened pattern deformable capacity. By comparing such conclusion can be got that the flattened pattern deformable capacity in this article is within the scope of permission. Then the fabrics are sewn into surface to test the efficiency of algorithm. The result showed that the new algorithm in this article is good for the improvement the practicality of flattened pattern and also with good stability.