These images are of an impeller from an automotive turbocharger made by Honeywell Turbo Technologies. The part was optically scanned, and the collected data processed with Geomagic software. The DSSP process--through which millions of data points become an impeccable virtual model of the original part, ready to be measured, tested, tweaked, and reproduced--unfolds below.
Step 1: The point cloud
Scan data is imported into the software as a collection of points called a point cloud. A complex object is represented by millions of points. In this case the number has been reduced by a process called decimation, and the turbo is represented by roughly a million points.
Step 2: Building polygons
In the next phase the program automatically converts the point cloud into a multitude of triangles--polygons, in DSSP-speak. The resulting polygon model can be saved as a stereolithography, or STL, file, which can be sent to specialized machines for rapid prototyping or custom manufacturing.
Step 3: Enter the NURBS
The software then transforms polygons into non-uniform rational B-splines, or NURBS, surfaces. This surfaced model, as it's called, can be used for inspection and engineering analysis, or passed on to a CAD system for design changes (with each tweak of the turbo tested virtually), tooling, and manufacturing.
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