First Release of D-Cubed's PGM

Cambridge, UK - 14 March 2003 - D-Cubed makes the first release of a new component that provides major enhancements to the productivity of the sketching environment in mechanical CAD systems.

The Profile Geometry Manager (PGM) is a major new component that extends the functionality of 2D DCM based applications, enhancing the productivity of dimension-driven operations in the sketching environment of mechanical CAD systems. The PGM's close integration with the 2D DCM enables a new range of variational operations that are not available in any other system.

Pre-releases of the PGM were first made available in November 2002. Among the more significant developments since that time has been support for offsetting ellipses and splines.

Overview

The PGM operates on profiles, a higher level data-structure compared with the individual, unbounded geometries used by the 2D DCM. Profiles can contain one or more open or closed loops.

The 2D DCM controls the shape of a profile through dimensions and constraints applied to the individual unbounded curves that are the basis of the connected series of bounded edges in the profile. However, the 2D DCM cannot, for example, ensure that a profile does not intersect with itself, or manage the geometry creation and deletion situations that arise in many design operations, such as offsetting. The PGM provides such functions, building upon the foundations provided by the solving capabilities of the 2D DCM. 

Offsetting

The most significant functionality in this first release is support for operations involving offset profiles. The PGM automatically maintains the validity of the offset through operations such as the insertion, removal, merging and splitting of edges.

Where there is a gap between the offset of a pair of adjacent edges the PGM will perform a capping operation to bridge the gap. Capping involves adding new edges or extending existing edges to ensure that the offset loop is contiguous.

As the offset distance increases, non-adjacent edges may intersect, edges may shrink to zero length, loops may intersect each other, edges may change direction and the offset of an ellipse or parametric curve may intersect with itself. The PGM will provide solutions to all these situations, automatically returning an offset loop which is useful to the end-user in a typical design context.

Future functionality

One of the strengths of the PGM is its tight integration of traditional 2D modelling operations with advanced variational design techniques. When solving constraints to a loop, for example, the PGM will continue to solve these constraints correctly even as other variational operations cause changes to the loop, such as the insertion or removal of edges. Some potential future developments include:

Constraint to loops: This would enable an application to apply constraints directly to a loop, including an offset loop, automatically handling the multiple bounded edges that form the loop. For example, an end-user could drag a coincident point along the entire length of the loop, seamlessly moving from each edge to its adjacent edge.

Constraints between loops: This would enable, for example, loops to be constrained to be a certain distance apart, tangent or symmetric to each other.

Constraints within loops: Such constraints could include loop length or profile area.

Event reporting: The PGM would report events to an application when changes occur to a profile that may violate the design intent. Examples of events include edges degenerating to a zero length or reversing direction, or the intersection of an inner loop (a hole) with an outer loop. Feeding this information back to the application will enable that particular design change to be prevented and the design intent to be maintained. Where possible, it is planned that the PGM will also be able to provide a range of actions that can be used by the application to automatically update a profile to account for the effects of an event.

Variational profile modelling: Generalised non-history based 3D solid modelling, where the end-user can straightforwardly build and modify parts without reference to the design sequence, is some way in the future. However, such functionality has not as yet even been implemented in the 2D sketching environment. One objective for the PGM is to combine the productivity and flexibility of 2D variational operations with a wide range of 2D modelling operations. Indeed, 2D offsetting is the PGM's initial variational modelling focus, but this may be extended to include 2D Booleans, blends, collision detection and clearance computations.

Variational feature management: This would be a major extension to the above variational profile modelling environment where features would be created, deleted, sized and positioned in the context of the current design configuration. One example would be modifying the number of holes in a plate as the size of the plate is changed.

The above list of projects is subject to change.

Conclusions

The PGM enhances the productivity of the 2D design environment in both 2D and 3D CAD systems through the extension of industry standard dimension driven sketching operations into new areas of high-level design functionality. This is achieved by working directly with the higher-level geometric data-structures found in the 2D design environment and automatically handling a wide range of new design changes, such as the addition, deletion and intersection of bounded edges.

Quick to integrate into an existing 2D DCM environment and having a major impact on fundamental operations at the sketcher level, the PGM brings early and significant benefits to most end-users.

About D-Cubed Ltd.

Founded in 1989 in Cambridge, England, D-Cubed provides software components and technical consulting services to the CAD/CAM/CAE application development industry in all areas of geometric, solid and variational/parametric modeling. Most of the world�s leading CAD vendors have adopted one or more of D-Cubed�s widely respected component technologies for integration into their end-user applications. We have never developed, and do not intend to develop, our own end-user applications. This focus avoids any competitive conflicts of interest with our customers.

www.d-cubed.co.uk

 

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