Inside Autodesk Fusion

Ralph Grabowski writes online at WorldCAD Access and reports weekly on the goings-on in the CAD industry in his upFront.eZine e-newsletter. Last year, he wrote “The Best of Both Worlds,“ which looked at how Siemens' synchronous technology bridges the gap between 3D modeling techniques.

Direct 3D modeling has been available in our industry for two decades now, but the largest CAD vendors studiously ignored it. Dassault Systèmes, UGS (now Siemens PLM Software), Autodesk and Parametric Technology (PTC) made their billions selling mechanical CAD that performed parametric modeling only.

Direct modeling was available from second tier suppliers, such as CoCreate, SpaceClaim and Rhino. If you wanted both direct and parametric modeling in a single package, you’d go with something like CadKey (now Kubotek USA) or IronCAD.

In 2007, the inventor of parametric modeling, PTC, purchase of CoCreate for its direct modeling. Next, Siemens PLM Systems added synchronous technology to Solid Edge, NX, and its CAx software. Quietly, Dassault has included some direct editing to some of it V6 software. Lastly, Autodesk began previewing direct modeling for Inventor at last December’s annual user group meeting.

Autodesk calls it Fusion as it represents a fusing that may take place in Inventor’s 3D modeling and user interface.

So far, Autodesk is only showing movies of Fusion at work. Some of it looks just like direct modeling found in other MCAD packages, even AutoCAD. You can push and pull faces, edges and vertices.

When you add complex features, such as multiple fillets or arrays of boltholes, the movies show Fusion previewing the changes and the user can change parameters interactively. Fusion also lets you directly edit 3D models imported from other CAD packages as well as attach parametrically designed parts.

None of this, however, is new.

The name hints at what is new: fusing direct and parametric modeling. Autodesk’s videos show direct-edited parts being “imported” back into the parametric modeling environment. Fusion analyzes the directly edited model to determine the features it contains and the result is a traditional-looking history tree.

Once back in the parametric environment, the model is not fixed. Apparently, you can edit it directly again. And bring it back as a parametric model. It is not clear, however, how much going back and forth models can handle. Perhaps one day choosing parametric or direct will become as trivial as switching between model and paper space in AutoCAD.

In the coming months, Autodesk will let us try out preview versions of Fusion. I feel this tentative rolling out is a better approach than that taken by Siemens PLM Software, who abruptly launched Synchronous Technology into the CAD community who still does not fully understood it.

Fusing the User Interface
In addition to fusing direct and parametric modeling, Fusion affects the user interface, as well. But, the interface changes are new only to Inventor, avoiding the ribbon and other fixed-in-place user interface elements. Indeed, parts of Fusion’s interface are borrowed from Autodesk’s own Alias software.

With Fusion, you interact with the model directly. Once you choose the feature to manipulate, you can push, pull, rotate, scale, and so on. For precise operations, an input box hovers near the cursor. Instead of shortcut menus activated by right-clicks, you’ll see a radial icon menu from which to choose options. A green checkmark and red X hover nearby to confirm or cancel changes.

During Autodesk’s rollout of Fusion to the media, they made negative reference to MCAD packages with an either/or approach to direct or parametric modeling. I asked Siemens for their reaction, and they replied, “It is important to understand that synchronous technology delivers a complete superset of functionality that allows for both parametrics/dimension-driven modeling AND direct geometry interaction (without constraints), but without the need of a history tree.

“Because of this there is no need for a direct-editing mode and a dimensional-editing mode. The so called push-pull technique is interesting to look at and can be fun to perform, but in actual practice, real work involves dimensional editing and you need this in the direct mode.”

In Summary
With the 2010 series of software, Autodesk targets everyone: Siemens and PTC at the high end, SpaceClaim and Rhino in the mid-range, and Google SketchUp at the low end. Indeed, Autodesk labelled competitor SpaceClaim to be a dead-end—unless they add parametrics to their direct modeling. SpaceClaim CEO Chris Randles retorted that “putting both [direct and parametric modeling] into the same tool is unrealistic and self-serving.”

Now that users of first-tier CAD software have a choice, which are they likely to employ—parametric or direct editing? The pros of one are the cons of the other, which is why one is unlikely to supplant the other. In the coming years, we should expect the two to merge seamlessly, as Autodesk is hoping to do with Fusion.
www.inventorfusion.com