Modeling Still Hard, Let’s Patch Things Up, says CAD Vet
Roopinder Tara posted on April 18, 2017 |
Versatile N-sided patch rescued from obscurity to form the basis of a new industrial design tool.
Figure 1 - The making of a stealth fighter. Phi uses n-sided patches to go from a flat shape to a smooth 3D model in 12 minutes.  Watch the video here
Figure 1 - The making of a stealth fighter. Phi uses n-sided patches to go from a flat shape to a smooth 3D model in 12 minutes. Watch the video here

Keith Mountain, once CEO of Spatial, may be the most polite person in the CAD industry. He apologizes for talking too fast - he’s rushing a demo for a journalist at COFES, who arrived half an hour late and asked Keith to make up the time. Places to go, people to meet.

Keith shows the pre-release version of his new industrial design tool, Phi. It runs in a browser and appears super easy to use. You can push and pull simple shapes, like putty, until they become the object you want.

“Like Rhino?” interrupts the journalist.

Yes, says Keith, like Rhino. He gently explains Phi’s advantages.

Phi is a product of Phenometry, maker of Phi, was formed by Keith, Dick Sowar (founder of Spatial) and two others. Despite his age of 73 and the input of his wife, Keith has no interest in retirement.

“I was teaching high school kids, and modeling even simple shapes was too hard,” he says, “Also, I love this business.” He’s not working too hard, he says. Modern applications make it easier than ever, collaborating with world-wide teams over the Internet. Phi is the work of a team of four developers in Greece, supposed experts in geometry constraint management. He doesn’t have to travel to Greece very often. I’m betting Keith’s wife, who also taught kids but is now retired, would prefer to visit Greece with Keith in person.

What is an N-Sided Patch?

Figure 2 - N-sided patch can smoothly blend between a number of edges. Picture courtesy of
Figure 2 - N-sided patch can smoothly blend between a number of edges. Picture courtesy of

N-sided patches permit complex surfaces to be defined by patches with any number of sides. This results in the ability to capture complex surfaces with fewer patches although with significantly more complex mathematics. “Our combination of N-sided patches with a proprietary geometry constraint manager provides for the ease of creation and editing desired by designers while providing the smooth G-2 surface quality required for most commercial design applications,” says Kieth.

The world of surface modeling is built on NURBS, or non-rational B-splines. A variation, T-Splines, offer an advantage in that, unlike normal NURBS, they can join other splines in a T-section. A variation on the theme is subdivision modeling, or sub-D, which allows users to poke and pull a surface by subdividing an otherwise simply defined shape (i.e., one with a flat or uniform radius curve) to make local bumps and valleys. The Parasolid geometry kernel, on which many popular MCAD apps are based, offers sub-D modeling, but only for certain, difficult areas.

Keith asks: Why not do all your modeling with N-sided patches? With sub-D modeling, you have to push and pull on points on a volume around the part. An N-sided patch allows you to cut out the middleman and push and pull directly on the part itself.

Currently, Phi parts can be stretched in a plane parallel to the screen, so the parts need to be oriented first. Interfaces with other modelers allow for movement in other planes - for example, pre-aligning planes so that the part can be stretched with any choice of direction despite the current orientation. 

Fighting for Ease of Use

Keith is targeting industrial designers with Phi, so Rhino is the obvious target. Keith sees products like Rhino as too inaccessible for most users. Like all CAD products, ease of use comes only after months of hard-earned experience.

“We want professional use, but with a 3rd grader’s attention span,” he jokes. He draws on his experience with SketchUp, the quintessential easy-to-use CAD product that has attracted tens of millions of users. SketchUp is embraced by both amateurs and pros. “Brad Schell, co-founder of SketchUp, always told me you have to fight with the developers to get ease of use – or the product quickly drifts towards the opposite.”

“You can just pull up on a rectangle and make walls, a house…” Likewise, pulling on an edge or face of a cube in Phi will turn it into an organic shape, add ergonomic handles, smooth transitions between interfaces, add air passages, and so on.


In the next two months, we will add parametrics, says Keith. That will make Phi really useful.

Phi, by Phenometry, is scheduled for release in two months. While pricing is not yet determined, it will be much cheaper than competitive products. 

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