Patent ID: 7321366

Claim:
A method for converting boundary data into cell inner shape data, comprising: a division step (A) of dividing external data constituted of the boundary data of an object into cells in an orthogonal grid; a cutting point deciding step (B) of deciding an intersection point of the boundary data and a cell edge as a cell edge cutting point; a boundary deciding step (C) of deciding a boundary formed by connecting the cell edge cutting points as the cell inner shape data; a cell classification step (D) of classifying the divided cells into a nonboundary cell including no boundary surface and a boundary cell including a boundary surface; a boundary cell data classification step (E) of classifying cell data constituting the boundary cell into internal cell data inside the cell inner shape data and external cell data outside the cell inner shape data; and step (F) of outputting the cell inner shape data to a display, wherein the cells are rectangular cells in two-dimensional representation, and in the cutting point deciding step (B), intersection points of boundary data and cell edges that have totally 2 4 =16 arrangement cases are decided as the cell edge cutting points, and the arrangement cases that become equivalence classes by rotational operation are decided as identical patterns so that the 2 4 =16 arrangement cases are further classified into 6 patterns, and in the cutting point deciding step (B), as for arrangement of each intersection point, data concerning the rotational operation and data concerning the identical pattern are stored in a storage device, wherein in the boundary deciding step (C), a boundary line made by connecting the cell edge cutting points is decided as the cell inner shape data for all the 6 patterns.