International Business Machines Corporation

William J Fitzgerald

Robert Nolan Wolfe

Franklin Gracer

Glenmore Lorraine Shelton, Jr

Raymond G Glemser, Ii

The lines representing each edge of each face of each object of a model for producing a multiple object image are segmented at line of sight intersections with other lines representing contour edges of visible faces. Each resulting edge line segment is checked against all visible faces to determine which are visible and which are invisible, and information on visibility is stored together with detailed information on each edge line segment for each object. The model is modified by changing the number of component objects and after each change checking the edge line segments for visibility only with respect to the changes associated with the changed component objects. This results in a substantial reduction in the required number of comparisons between segments and faces as compared to prior methods.

Method for producing planar geometric projection images

A computer aided drafting (CAD) procedure presents, for a three dimensional (3D) object to be modeled in a general purpose computer, dimensional and tolerance parameters appropriate to changes of view or parameters. The procedure requires but one model, the three dimensional solid model, for producing both dimensioned displays of the model and dimensioned drawings of views of the model. Dogleg extension lines are used to express 3D dimensions without ambiguity. These dogleg extension lines facilitate the presentation of information on paper or on a display screen and permit convenient alteration of presentations of 3D illustrations, with automatic correction of dimension and tolerance presentation. The operator of the CAD system enters dimension and tolerance information on a plan or elevation view, and this information is automatically converted to an appropriately corrected and presented axonometric presentation.

3D Dimensioning in computer aided drafting

A method and apparatus for determining the X--Y coordinates on the raster of the intersection of two curves one of which is stored in the display system raster refresh buffer. The second curve is generated by a curve generator or some other source of sequential X--Y coordinate data defining the X--Y coordinates on the raster where the second curve would lie. As each X--Y coordinate is generated by curve generator it is translated into a buffer address and the contents of that address in the buffer memory are accessed and a determination is made to see if said first curve exists at that address. If an element of the first curve is found to exist in the buffer store at the generated address location, it is known an intersection point has been found and the appropriate X--Y address is gated from the system to utilization means. According to a further feature of the invention, if a plurality of intersection points are found for two particular curves, averaging means are provided for at least approximating the midpoint of the actual intersection of the two curves and said midpoint address is gated out of the system as the intersection point. A method and means are also provided for determining if two curves have a point of tangency when they exist on two adjacent raster lines but do not actually intersect.

Method and apparatus for automatically determining the X-Y intersection

By means of a suitable data entry device such as an electronic digitizing tablet or graph board, items of data respectively defining the original configuration of a roughly sketched object and the desired final proportions thereof are entered into a stored table called a 'pointing sequence list' (PSL), which is capable of storing all of the information required to define both the original form and the desired final configuration of the object. Initially the PSL contains positional entries representing the coordinates of definitive points on the roughly sketched object and dimensional entries specifying the proportions which the object is to have in its final delineation, all arranged in an order corresponding to a predefined pointing sequence which is followed by the operator when he enters the necessary items of graphic information into the system. The initial PSL subsequently is converted to a new PSL by a rectifying procedure which modifies the coordinates of the previously entered points where necessary in order to effect horizontal and vertical alinements of points which are supposed to be located on common axially directed lines. Whenever a coordinate is modified to effect an axial alinement (or in some instances a joinder) between two or more points during the rectification process, the respective entry which corresponds to the modified coordinate in the new PSL is provided with a 'pointer' to the PSL location storing the entry which specifies the referenced coordinate, thereby establishing an equivalence between these two entries. The linkages among equivalent entries are preserved during subsequent processing operations performed upon these entries, so that a change in one member of each set affects all of the other members thereof. The new PSL entries are then further modified where necessary in accordance with the proportions specified by the various dimensional entries, so that the PSL ultimately specifies the positions of points defining a rectified and proportioned version of the original rough sketch, thereby enabling a finished drawing or other final representation of the object to be produced from these PSL entries.

Growing community of inventors

Ridgefield, CT, United States of America

William J Fitzgerald