|By George Maestri
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.
|Although the FreeForm system is widely used for design and manufacturing, it has found a home in entertainment applications as well. Image courtesy Jay Kushwara, SensAble Technologies.
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 say it's exactly like working in the real world. As I noted in my first review of the product (June 2001, pg. 56) you're essentially sculpting with a virtual ball on a stick rather than with your fingers. I wish the feedback were smoother, however, as I could feel a stair-stepping effect on parts of the surface, particularly along tightly rounded corners. Still, the sense of touch is a great feedback tool.
Along the way, FreeForm has gained a number of features aimed at helping NURBS modelers, which are contained in the FreeForm Plus upgrade. The NURBS options allow modelers to trace NURBS curves and patches along a FreeForm surface, much like in packages such as Paraform. These NURBS objects can be fitted into a seamless patch network, which can then be modified in FreeForm or exported though the IGES format to most popular 3D packages. Version 6 also comes with additional features such as a new interactive technique for modeling with texture maps, and integrated features for splitting clay and articulating pieces.
Altogether, FreeForm has become far more accurate. It supports a number of measuring tools that enable you to sculpt models more accurately than in previous versions. All in all, I think many users will find FreeForm a good supplement to more mainstream modeling packages. It enables you to delve into 3D space and use your sense of touch, which should be helpful to traditional artists making their way into the digital realm. The package is particularly good for those involved in industrial design, as it supports a large number of output devices. Those involved in content creation, such as animation studios, might find FreeForm Plus valuable because of the integrated NURBS capability.
Getting used to a haptic interface does take time, and I'm not sure it's for everyone. But for those who need a sense of touch with their models, FreeForm might just be the ticket.
George Maestri is president of Rubberbug, a Los Angeles-based animation studio specializing in character animation.
SensAble Technologies www.sensable.com
Price: $15,000 for FreeForm, $24,000 for FreeForm Plus.
Minimum System Requirements: Windows 2000/XP; 933MHz Pentium or dual 400MHz processors; 512MB of RAM