By David Cohn
Creating free-form surfaces is challenging and time-consuming, particularly when you have to create them from point cloud data obtained from physical object scans. Geomagic Studio 2.0 from Raindrop Geomagic simplifies this task by automating the creation of NURBS surfaces from point-cloud and polygonal information, enabling you to rapidly create 3D models for design and manufacturing.
Geomagic Studio consists of three programs-Wrap, Shape, and Decimate-within a unified interface that guides you through the various processes. Geomagic Wrap is an automatic surface-generation tool that mathematically "wraps" a polygonal surface around point-cloud data. Wrap accepts IGES point clouds as well as data from MicroScribe digitizers and Cyberware, Digibotics, Hymarc, and other scanners.
 |
| Raindrop Geomagic Studio's Wrap functions automate the construction of polygonal surfaces from scanned or digitized point cloud data. |
Geomagic Shape converts polygonal models into surface models consisting of NURBS patches. The resulting model can be saved and exported in various file formats, including DXF, IGES, GeomView OOGL, STL, VRML, Wavefront (OBJ), Inventor (IV), 3D Studio (3DS), and Geomagic's own WRP. The third module, Geomagic Decimate, is a polygon reduction tool for lowering the number of triangles in a model-thus improving rendering speed and reducing file size while preserving surface geometry.
To run Geomagic Studio through its paces, I loaded a sample point cloud data file supplied with the program. Wrap con sists of three phases. During the "point" phase, you can modify the point set using editing methods such as cropping or erasing to remove unwanted or extraneous points. Next, in the "wrap" phase, the program computes the polygonal model. This step occurs automatically and, after several minutes of processing, produces a fairly ac curate initial, editable model. The length of processing time depends on the number of points in the model. My experience using the samples provided with the program ranged from 2 to 3 minutes for most simple scans to nearly 15 minutes for a sample containing more than 400,000 points.
The final "polygon" phase consists of operations such as decreasing the number of triangles (here is where Decimator comes in), smoothing surfaces, creating straight edges and planes, and adding and moving points to provide finer control over surface deformation. These procedures are aimed at making the surface of a model suitable for other applications.
 |
| Geomagic Shape lets users focus on form, not mathematics, to translate polygonal models created in Wrap or other programs into watertight NURBS surfaces that can be imported into other CAD/CAM systems. |
After I made my polygon model, I moved to Shape to create the NURBS surface. First, an optional "detect features" step let me adjust the granularity (the number of possible feature lines) and feature level (the amount of curvature re quired for a line to be identified as a feature line).
During the "construct boundaries" step, the program converted the polygonal model into quadrangular patch es, which served as the framework for the NURBS patches. The next step, "edit boundary," enabled me to adjust the size and shape of the patches to obtain more shape regularity.
As a final preparation for calculating the NURBS surface, I used the "construct grids" step to place a grid structure within each boundary patch. With this, I could specify the grid resolution and, after it was constructed, edit the grids.
The final step in using the Shape module involves the "fit surfaces" function, which constructs the actual NURBS surface. This process makes all patch boundaries and corners continuous except for those marked as sharp lines. After constructing the surface, I was able to increase the accuracy and detail of specific patches, merge and delete patches, and edit control points. After I finished, I saved the NURBS surface in IGES format and had no problem opening the model in several different CAD programs.
At $19,995, Geomagic Studio is a serious investment. But if you consider its ease of use, and how it can reduce days of painstaking work to a few hours of intelligent interaction, it starts to look like a bargain.
David Cohn is a computer consultant and technical writer based in Bellingham, Washington. Price: $19,995 standalone; $24,995 floating network license (per seat)
Minimum System Requirements: Pentium-based 333MHz PC running Windows 98/NT; or SGI workstation (R10000 or higher) running Irix 6.3; 64MB of RAM; 40MB of disk space
Raindrop GeomagicResearch Triangle Park, NC
800-251-5551; 919-474-0122
www.geomagic.com