[Japanese | Thesis | Researches in Minoh Lab | Minoh Lab]

Designing Patterns of a Garment by Direct Manipulation of its 3D Shape

In this paper, an interactive method for designing a paper of a garment in 3-dimensional(3D) space is described.

For manufacturing a garment of custom-made that satisfies the client's preference and fits his/her body, various kinds of procedure using real garments are carried out repeatedly. In order to perform these work more efficiently, methods for simulating the 3D shape of a garment in virtual space have been proposed.

To design a garment of custom-made for a client, it is important for the client to express his/her intention about the shape of the garment precisely. Thus, the environment that enable the client to participate in a garment design process is necessary.

In the conventional process of checking the 3D shape after completely designing a paper pattern, the user has to predict the change of the 3D shape by the modification of the paper pattern. This process requires expertise in the garment design. Such a system does not allow the user unfamiliar with garment design to participate. On the other hand, for a system that generates paper patterns automatically after designing the 3D shape of a garment, the position of cuts called "darts" must be determined automatically. But it is very difficult.

In our work, we propose a method of designing 2D paper patterns by manipulating the garment in 3D space interactively. Generally speaking, a garment design can be performed by selecting standard models of the paper pattern of each portion such as a sleeve, a body and so on, and combining them after modifying the paper pattern of each model. In our system, two or more kinds of garment model which are different in the positions of darts are prepared for each part of a garment. When a user intend to increase the darts, it can be done by selecting the garment model with appropriate positions of darts instead of changing the darts directly. Thus, design operation to a garment is defined as modification of the paper pattern of each model.

In our system, a garment is represented by the quadrangle structure grid model. When a paper pattern is represented by the grid model, the number of points on the outline to be sewn with each other must be equal, and the outline need to be approximated as nearly in shape as possible. The quadrangle structure grid is suitable for these conditions. In the case of a complicated figure of a paper pattern containing darts, there is a problem that the arrangement of the grid is distorted extremely. Hence, we first divide a paper pattern into sub-simple areas in which the grid does not need to be distorted. In this way we cope with the problem of distortion of the grid.

In order to design 2D paper patterns by manipulating the garment in 3D space, the 3D operations on the garment shape have to be mapped into 2D paper pattern. We approximate the shape of each part of a garment by a column, and the garment design is performed by "column metaphor", in which the manipulation in 3D space is represented by the intuitive operation for the deformation of a column. When a 3D vector for design is given in the manipulation, we define the components of vector, which corresponds to the radius, the center axis and the rotation coordinate of a column, and those components are interpreted as the expansion of the radius, the stretch along the center axis and the bend along the horizontal axis. Since the quadrangle structure grid constituting the garment model is arranged along to the vertical and horizontal direction of the garment model, we define the axis characteristic to the garment model corresponding with each component on column metaphor based on arrangement of the structure grid, and find the change in 2D which corresponds to the manipulation in 3D.

Moreover, for the efficient design, user can select the target of the design operation from the primitives of the grid, i.e. a surface, an edge, and a point.

We verified the above technique through the design by users unfamiliar with garment design. As a result, the proposed method can reduce the time required in design by about 50\% compared with the previous method.

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