Issue: Volume: 24 Issue: 6 (June 2001)

FreeForm V3

By George Maestri

Digital artists often complain that although workstations are good at providing an experience for two senses-sight and sound-they don't provide a similar experience for the important sense of touch. A few manufacturers have tried to solve this problem through the use of haptic interfaces that enable users to directly interact with digital objects and data as they do in the real world: using their sense of touch. One such manufacturer, SensAble Technologies, appears to be on the right track.

SensAble is the developer of FreeForm, a modeling system that found its initial niche with toy, footwear, figurine, and ceramics makers-generally at companies where users had difficulty creating by hand in clay or wax the detailed, organic forms their products required.

The FreeForm approach has more recently gained momentum with users modeling for digital content creation and industrial design. As a result, SensAble put into Version 3 some features that are designed to support these new workflows-among them the ability to export models as NURBS surfaces, and to create multi-part models. According to SensAble, further functionality needed in the DCC and industrial design markets is being incorporated into FreeForm Version 4, which is scheduled to ship this summer.
With FreeForm's surfacing tools, you can draw curves on any object for export into other 3D packages.

The FreeForm system consists of Phantom, an articulated arm with a stylus on the end that provides positioning in put and force-feedback output; Ghost, which works as the "physics" engine, enabling users to deal with objects and physical properties such as location, mass, and friction; and application software.

Phantom comes in several sizes, ranging from a desktop version to a 3-foot-high model that gives you a large work area. I used the desktop version, which I attached to my computer through a parallel port.

The modeling application uses a clay-sculpting analogy, in that it provides various-size lumps of "virtual clay" in the form of spheres, boxes, and cylinders. You model these lumps by pushing and pulling on their surfaces using tools shaped like spheres, boxes, scrapers, and capsules, to name a few. This is where force feedback enters into the equation. When you use Phantom to run the tools along a model's surface, you can feel the model's contours. Pushing or pulling the surface creates resistance, enabling you to feel the deformations as they occur.

Using Phantom took some practice, but I soon got the hang of it. I can't say it was exactly like working in the real world, as you're essentially sculpting with a virtual ball on a stick rather than with your fingers and thumbs. Still, the sense of touch was a great feedback tool.

Although the idea of FreeForm sculpting is nifty, on its own it's not as accurate as might be required for some users, such as those involved in CAD, industrial design, or other high-tolerance markets. To facilitate this, SensAble provides software tools such as planes that can contain reference images you can use as templates. You also can draw curves for more accurate modeling and loft those curves into basic shapes to create objects. Plus, you can draw curves on the surface of any object and use them to emboss the model or smooth it. Finally, you can use curves to wire-cut a model, much like in sculpting, which can be very helpful. According to SensAble, Version 4 will further extend the use of 3D curves to facilitate modeling.

Version 4 also will feature global deformation tools, so users can pull and squeeze models and modify them without losing finely crafted details. And it will feature new patch tools that will enable users to directly model smoothly flowing surfaces.

In Version 3, SensAble provides a surfacing module that enables users to draw and snap curves on a surface to create patches. The curves or patches can then be exported to an animation or CAD package as IGES files. Users who want to deform or animate their models, such as character animators, will still need to stitch the patches together using their animation software's surface continuity tools.

Artists who are already proficient at NURBS or polygonal modeling, however, might prefer their own modeling software, mostly because it's simpler to model in the package you'll ultimately use for animation. It might be a good idea if SensAble created plug-ins for the major 3D modeling and animation packages.

All in all, the FreeForm system does what it promises, in that it enables artists to feel their models as they sculpt them and, therefore, work in a more natural, intuitive way. This product shows a tremendous amount of promise.

George Maestri is a writer and animator living in Los Angeles.

Price: $15,000 with desktop Phantom
Minimum System Requirements: Windows NT 4; dual Pentium II 300MHz processors; 512MB of RAM; graphics card with 32MB of RAM and hardware-based OpenGL acceleration
SensAble Technologies