3D dimensioning in computer aided drafting.

摘要

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.