FreeForm Version 6: SensAble's haptic system evolves.(SensAble Technologies)

Interacting with 3D objects on a computer is a conceptual stretch for many people. From a visual standpoint, it's difficult to view a 3D object properly on a 2D screen. From an interactive standpoint, the computer mouse works in only two dimensions. The artist's sense of touch is also ignored by most modeling packages. This is where haptic interfaces that allow users to `feel' an object as well as manipulate it in 3D step in. SensAble Technologies' offering along these lines is FreeForm, a hardware/software system now in its sixth generation that allows modelers to manipulate and feel objects in true 3D space.

The FreeForm system consists of three elements: Phantom, an articulated arm with a stylus that provides positioning input and force-feedback output; Ghost, which works as the "physics" engine, enabling physical properties such as location, mass, friction, and stiffness; and modeling software. The software comes in two flavors: FreeForm has a full suite of touch-based modeling tools and FreeForm Plus adds advanced design tools for creating precise features, deforming models, and exporting models as NURBS surfaces.

The Phantom interface device comes in several versions, ranging from desktop size to a three-foot-high model. For this review, I used the desktop version, which I attached to my computer through a parallel port. Users with dongle-protected software may need to install a second parallel port interface card, which will take up a valuable slot--important to note because although the parallel-port interface is becoming somewhat antiquated and users might prefer a more up-to-date USB or Firewire interface, the parallel-port interface has the advantage of lower latency, which can improve the quality of touch sensation.

FreeForm is basically a modeling application that uses a clay-sculpting analogy; it provides "virtual clay" in the form of spheres, boxes, and cylinders of different sizes. You model these objects 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 its contours. Pushing or pulling the surface creates resistance, which enables you to feel the deformations as they occur. The more you push and pull, the more the surface deforms.

Using Phantom takes a bit of practice. I can't ...