International Business Machines Corporation

Hiroshi Minakata

Makoto Ono

Shigeru Kuriyama

Kazuya Shimizu

Naoki Urano

An apparatus and method in which an operator can input a three-dimensional (3D) graphics to a graphic system by performing an operation that is as if he were sketching on a paper surface. A line segment of two-dimensional (2D) data is input through an input device such as a mouse, and is then temporarily stored in a storage device as well as being displayed on a 2D display screen. The line segment of 2D data is converted to 3D data when it obtains information in the depth direction based on its relationship to another line segment that constitutes a 3D graphics and has 3D data already. 3D data of line segments that have that data in addition to 2D data are stored in a storage device, and are projected by a projection conversion circuit onto a 2D projection plane that has been set by a visual field input device, so as to be converted to 2D data, which are then displayed on the display screen. Therefore, the line segments that have already been converted to 3D data are displayed on the display screen together with the line segments that have been input through the input device and still have only 2D data. An operator can construct a 3D graphics constituted of 3D line segments simply by inputting 2D line segments as if he were sketching.

Apparatus and method for converting line segment data to

A semitransparent spherical surface having as its center O, a fixed point in an object being displayed on a screen of a tablet, is generated so as to enclose the object. Then, three degrees of freedom for orientation are determined by pen-manipulation on the spherical surface. That is, a plurality of points (P0-P3) on the spherical surface are specified in a predetermined order. Points P0 and P1 specify two polar surface coordinate positions on the spherical surface for rotation of the object in a polar coordinate system and simultaneously specify a rotation axis OP1 connecting the center O to point P1. Then a rotation angle .alpha. about this axis OP1 is specified by the specification of points P2 and P3. Then, calculations for rotating the object to the specified orientation are performed, and the rotated object is displayed. According to this method, the object in three-dimensional space can be rotated to an arbitrary orientation in a desired manner.

Graphic display method and apparatus for rotating an object in

A handwriting input method and apparatus is disclosed which generates a single line segment from a group of input line segments which are input by a user. The input line segments may be overlapping or disconnected short line segments, thereby allowing the user to enter lines in a free stroke format, much the way an artist sketches. For each of the input line segments a plurality of variable parameters are detected from the stroke data. The parameters for each input line segment are converted to a three-dimensional weighting function. The weighting functions for different line segments are combined, the edge of the resulting combined function is detected, and that edge is displayed as a line segment on a display device.

Handwriting input method and apparatus

A method for generating a multisided patch in which the expression form of each boundary curve and topology of the curve network can freely be set, curve formulae can be simply input, and high continuity. By inputting data of boundary curves to multisided patch generator via editing means which generates and edits curves, and blending sweep surfaces in two stages, a free-form surface is generated as a surface interpolating them. That is, data of a plurality of boundary curves is inputted to multisided patch generator, each given curve is swept by sweeping means along the curves intersecting it to generate surfaces, and the surfaces are blended by blending means in two stages, thereby generating a free-form surface. Since the surface formulae can be defined on the basis of the curve formulae of the boundaries, topology of the curve network and the descriptive form of each curve can freely be set, so that the boundary curve formulae of a multisided patch can be simply input by directly drawing the curve shapes on defined two-dimensional planes. In addition, geometric continuity of the generated surface is high because continuity of the given curves is high.

Growing community of inventors

Tokyo, Japan

Hiroshi Minakata