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Parametric/direct CAD integration

Qiang Zou

TL;DR

This paper surveys parametric and direct CAD modeling, analyzing five public integration approaches and arguing that seamless integration remains unsolved. It explains solid modeling representations (B-rep and CSG) and contrasts parametric versus direct paradigms, emphasizing the challenge of cross-layer information consistency. The main contribution is a critical synthesis showing that current strategies fall short due to topology-geometry-constraint dissonance, motivating pursuit of constraint-aware, direct-and-parametric frameworks such as variational direct modeling. The work highlights the practical significance of resolving integration to unlock a robust, next-generation CAD capable of flexible edits with reliable design intent.

Abstract

In the history of computer-aided design (CAD), feature-based parametric modeling and boundary representation-based direct modeling are two of the most important CAD paradigms, developed respectively in the late 1980s and the late 2000s. They have complementary advantages and limitations, thereby offering huge potential for improvement towards an integrated CAD modeling scheme. Some believe that their integration will be the key characteristic of next generation CAD software. This paper provides a brief review on current parametric/direct integration approaches. Their basic ideas, advantages, and disadvantages will be discussed. The main result reads that existing integration approaches are far from being completed if seamless parametric/direct integration is desired. It is hoped that, by outlining what has already been made possible and what still remains problematic, more researchers will be attracted to work on this very important research topic of parametric/direct integration. This paper serves as a complement to the CAD paper titled ``Variational Direct Modeling: A Framework Towards Integration of Parametric Modeling and Direct Modeling in CAD." Cite this work as follows: Qiang Zou, Hsi-Yung Feng, and Shuming Gao. Variational Direct Modeling: A Framework Towards Integration of Parametric Modeling and Direct Modeling in CAD. Computer-Aided Design 157 (2023): 103465.

Parametric/direct CAD integration

TL;DR

This paper surveys parametric and direct CAD modeling, analyzing five public integration approaches and arguing that seamless integration remains unsolved. It explains solid modeling representations (B-rep and CSG) and contrasts parametric versus direct paradigms, emphasizing the challenge of cross-layer information consistency. The main contribution is a critical synthesis showing that current strategies fall short due to topology-geometry-constraint dissonance, motivating pursuit of constraint-aware, direct-and-parametric frameworks such as variational direct modeling. The work highlights the practical significance of resolving integration to unlock a robust, next-generation CAD capable of flexible edits with reliable design intent.

Abstract

In the history of computer-aided design (CAD), feature-based parametric modeling and boundary representation-based direct modeling are two of the most important CAD paradigms, developed respectively in the late 1980s and the late 2000s. They have complementary advantages and limitations, thereby offering huge potential for improvement towards an integrated CAD modeling scheme. Some believe that their integration will be the key characteristic of next generation CAD software. This paper provides a brief review on current parametric/direct integration approaches. Their basic ideas, advantages, and disadvantages will be discussed. The main result reads that existing integration approaches are far from being completed if seamless parametric/direct integration is desired. It is hoped that, by outlining what has already been made possible and what still remains problematic, more researchers will be attracted to work on this very important research topic of parametric/direct integration. This paper serves as a complement to the CAD paper titled ``Variational Direct Modeling: A Framework Towards Integration of Parametric Modeling and Direct Modeling in CAD." Cite this work as follows: Qiang Zou, Hsi-Yung Feng, and Shuming Gao. Variational Direct Modeling: A Framework Towards Integration of Parametric Modeling and Direct Modeling in CAD. Computer-Aided Design 157 (2023): 103465.
Paper Structure (10 sections, 3 figures)

This paper contains 10 sections, 3 figures.

Table of Contents

  1. Introduction
  2. A brief on solid modeling
  3. A brief on parametric and direct modeling
  4. Parametric/direct integration
  5. Pseudo-Features
  6. Dual Modes
  7. Synchronous Technology
  8. Operation Translating
  9. Constrained Direct Modeling
  10. Conclusion

Figures (3)

  • Figure 1: Illustrations of the notions of closed (left), regular (middle), and manifold (right).
  • Figure 2: Examples of B-rep (a) and CSG (b).
  • Figure 3: Illustration of the pseudo-feature method and its limitations.