Browse Prior Art Database

New Interface for Form-Feature Based Geometric Modeling

IP.com Disclosure Number: IPCOM000106526D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 115K

Publishing Venue

IBM

Related People

Masuda, H: AUTHOR [+2]

Abstract

Disclosed is a design and implementation of the interface for form-feature based 3D solid modeler. In form-feature based modeling, a complicated 3D object is decomposed into a set of simple primitive shapes such as block, step, through hole, etc., those are called form-feature.

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This is the abbreviated version, containing approximately 52% of the total text.

New Interface for Form-Feature Based Geometric Modeling

      Disclosed is a design and implementation of the interface for
form-feature based 3D solid modeler.  In form-feature based modeling,
a complicated 3D object is decomposed into a set of simple primitive
shapes such as block, step, through hole, etc., those are called
form-feature.

      The usual feaure-based modeling which is applied by existing 3D
CAD system is illustrated in Fig. 1.  When the designer selects the
feature, first, its specification should be given by parameters to
determine its shape, then the transformation matrix should be
calcurated to move the feature to the appropriate position, and
finally, Boolean set operation is performed between the base obejct
and the feature to get the resultant shape.

      The problem is that the designer should specify all the
parameters before the feature is created.  If the resultant feature
does not satisfy the designer, he should investigate the reason and
recompute the parameters again and again until he gets a satisfiable
result.  This is very inconvenient especially at conceptual design
phase.

      The new idea enables the designer to specify the feature by
moving the dial or other input devices while watching the effect of
the change on the display screen.  To realize this kind of direct
manipulation, following technologies are introduced:

o   Classification of form-feature by the number of faces that
    coincide those of the base object.

o   Extraction of the parameter that modifies the form-feature
    keeping the constraints of the face-face coincidence.

o   Real-time transformation of the form-feature on display screen.

      Fig. 2 shows the feature classification by (i) topological
structure such as four-sided prism, three-sided prism, cylinder, and
(ii) Boolean operation of subtraction or addition, and (iii) the
number of coincide faces.  Here, (iii) is the newly introduced
criteria.  This is important because it holds the meaning of feature
itself.  For example, "through hole" has two face conincidence,
whereas "blind hole" has one.  Another importance is that it
constrain the shape of...