3D Simulation For Complete Knitwear Based On Loop Structure

With the rapid development of the new generation of information technology,a new round of industrial revolution and innovation emerges in the world,and the manufacturing industry is shifting from the traditional production mode to the intelligent production mode.The complete garment technology knits the whole product at one time,effectively changing the production mode of the traditional sweater which mainly relies on manual work,as well reduceing the production process and shortening the production cycle.The product has a three-dimensional silhouette and beautiful visual effects to meet high-end customization.The complete knitwear are difficult to develop due to complex knitting processes and design.As an intelligent tool,3D simulation software provides good communication between designers and technicians,improves product design and variability in a short time,and reduces the number of proofing.Therefore,the development of a 3D simulation software for complete knitwear can greatly improve the development efficiency of new products and promote the transformation and upgrading of sweater enterprises.This paper starts from the knitting process of the complete knitwear and uses the loop as the basic unit for 3D simulation.Firstly,the knitting principle of complete knitwear is analyzed,and the knitting processes of rib,sleeve body connection,shoulder seam and collar are studied,also the mathematical model of knitting technology information is established.Then,the loop structures of the complete knitwear are studied.The stitch mesh models of basic stitch,fancy stitch,connecting stitch and other commonly used stitch in complete knitwear are established,and so as to the relationships between the process data and stitch meshes.The stitch mesh model includes the mesh type,stitch mesh points and loop geometry points.Based on the actual fabric and quadratic Bezier curve,the coordinates of the geometry points are deduced backwards,and the parameter relationship between the geometry points and the mesh points is established.On the basis of the process data and stitch meshes,stitch meshes of the 2D garment pieces are calculated according to the clothing pattern segment.Then on the basis of the 2D stitch meshes,a simplified spring particle model is established to simulate the deformation of the fancy stitches,and the force analysis of the tuck,float and trnasfer is carried out.The displacement of surrounding particles is calculated using Verlet numerical integration method.The problem of excessive stretching and collision during deformation are solved by adding additional tension and repulsion.Compressibility coefficient is introduced to simulate the deformation of rib stitches.The spatial transformation matrix of each triangle is calculated according to the characteristics in the virtual display which the spatial transformation matrix of each triangle is calculated according to the characteristics in the virtual display.The triangle of the 2D garment model to which the 2D stitch mesh points belong is calculated,and the loop mesh points are transformed into the same space as the triangle to obtain the 3D loop mesh model matching the three-dimensional garment model.The simulation of 3D loop structure includes three steps: loop path generation,loop entity generation and loop surface rendering.According to the relationship between the geometry points and the mesh points,the geometry points in the 3D garment are calculated by increasing the loop thickness in the normal direction of the loop meshes.On this basis,the yarn path curve is generated by using the quadratic Bezier curve for interpolation.The tangential rotation frame of each interpolation point on the path is calculated,and the circular cross section with the interpolation point as the center sweeps along the loop path according to the tangential rotation frame to generate the yarn surface.PBR technology is proposed to render the yarn surface,simulating the details and twist of the yarn surface and increasing the realism of the yarn.The simulation effect and time based on PBR material are analyzed,and it is concluded that the degree of subdivision of the loop surface has little effect on the simulation effect,but the simulation time is long when the degree of subdivision is high.Based on this,the loop entity with low surface subdivision is selected for the 3D simulation of complete knitwear.With the above methods of loop stitch modeling and loop structure realistic simulation,a CAD simulation system for complete knitwear was developed via Visual Studio and OpenGL.Rendering was achieved through a programmable pipeline.Rapid simulation of multiple styles of complete knitwear were realized,which verified the feasibility of the simulation method.The above four aspects are all studied to realize the 3D simulation of the complete knitwear.This paper focuses on the 3D loop structure based on knitting technology,aiming at to realize a 3D simulation system of complete knitwear with knitted loop structure and reality.This system will shorten the development cycle for complete knitwear and lay the foundation for personalized fashion customization.