Gradually, b-rep modelers expanded their geometry classes to support analytics (cylinders, spheres, toroids, and so on), and eventually a variety of surface representations, such as NURBS.įacets became the primary method of representing scenes in image generation, such as for flight simulators, where the image generation pipeline was built on facets for performance. The Continual Development of Representations The managing directors of Shape Data split off to form Three-Space Ltd, the company that created ACIS.
BRICSCAD HOW TO CHOSE TOP FRONT SERIES
This was just the first of a long series of acquisitions passing Shape Data from one company to another, ultimately ending up at Siemens.ĪCIS. The D/T-D function was later removed from Romulus.Įvans & Sutherland was a distributor of Romulus, and then later acquired Shape Data. The company, unfortunately, had some very strong positions on how a solid modeler ought to be used and, as a result, did not realize advances like parametric modeling and PMI when they presented themselves. The D/T-D function was released with Romulus v5.2.ĭuring a design review I had with Bob Sproull, Bob pointed out that the D/T-D framework we had implemented in Romulus could be extended to be a parametric modeling system. It can trace its roots to the earlier D/T-D work in Romulus.Īfter Kepler, I ended up relocating to Shape Data and led a project to implement encoding dimensions and tolerances in Romulus and automatically generating engineering drawings, easily a decade or more before PMI. John Owen at Shape Data developed his dimensional constraint technology, which is the basis of D-Cubed. Shape Data Ltd was the company that originated Romulus and later Parasolid. When the Kepler project’s proof-of-concept was completed, it was decided to no longer pursue the approach.ĭ-Cubed. (Kepler really wasn’t an acronym the project lead chose the name due to the historical individual’s role in astronomy.) Objects were built in the Kepler environment, and then the corresponding modeling commands were passed to Romulus to instantiate the design, often taking many minutes to calculate on a DEC VAX 780 mini-computer. Kepler was an application development environment front-end to Romulus that provided a design space, giving designers a degree of interactivity not possible with solid modelers at the time. After graduating from CMU, I joined the Kepler project at Evans & Sutherland. Only later were NURBS surfaces introduced and there was a big debate over whether analytics should be converted to NURBS equivalents and all intersections done in NURBS - or whether to continue to maintain the discrete surface types for precision and efficiency. Romulus introduced analytics and had discrete intersection routines to do surface/surface intersection calculations based on surface type. The BUILD research was commercially spun off into Shape Data, which was the precursor to ACIS and Parasolid. Being developed in parallel to GLIDE was Ian Braid’s BUILD project at Cambridge University in the UK, another b-rep program. GLIDE subtracting polyhedrons (left) to arrive at a new shape (right). I was a member of the GLIDE team 1979-1981, where I was responsible for implementing the Euler operations from the original BDS, which were written in BLISS, to GLIDE’s Pascal. Kevin Weiler, who originated non-manifold topology b-reps as his PhD thesis at Rensselaer Polytechnic Institute, was one of the members of Eastman’s GLIDE team. It was headed up by Chuck Eastman, who is generally acknowledged as the father of BIM. The GLIDE program was funded by the Army Corps of Engineers who wanted a system to model their various facilities.
GLIDE stands for “graphical language for interactive design” and was a research program in the architecture department at Carnegie Mellon University. It turns out that faceted models were the very first b-rep structures, referenced in 1977 by CMU’s GLIDE, a polygonal modeler. In the upFront.eZine article on Solid Edge 2022, Dan Staples makes the following comment: “I do think is a final frontier here, because meshes for a long time were the domain of the film industry and character modeling.”
Inside the Business of CAD | 8 November 2021