Press Release

3D Scanning - Magic Made Practical

George Hatzilias

3D scanning technology has been tailored to mainstream CAD, resulting in unprecedented compatibility and broadened applications.

While 3D laser scanning equipment has been available for more than 15 years, computing power has only recently caught up with 3D technology, resulting in a quantum leap for reverse engineering and quality inspection applications, which can now fully use large amounts of digital scan data. For example, 3D scanning inspection has advantages over CMM or optical comparator techniques because it offers a color map of the entire object and can be viewed via color map, from any angle, all at once (see Figure 1). Major advances in 3D scanning applications are appearing across a wide range of industries, including aerospace, automotive, marine, medical, dental, plastics, tooling, architecture, and entertainment. Following is a description of some of these developments.

Soft Internal Non-Contact Scanning (SINCS)

When most people think of 3D scanning, they think of capturing the exposed surfaces of an object or assembly - and rightfully so, because most optical systems are based on a "line of sight." However, the soft internal non-contact scanning (SINCS) breakthrough makes it possible to effectively see through parts.

The anatomical CAD model in Figure 1 was generated using SINCS. The engineering challenge was that a defunct supplier had left designers with only a physical sample and no CAD. The solution involved a special new compound (SINCOR) that is dimensionally stable, will not adhere to part surfaces, is able to accurately capture internal details, and is able to be removed without losing its shape. The external surfaces were scanned first. Once the inside was cast in SINCOR, the internal casting was removed and scanned in to represent the interior surfaces of the part. Internal and external surfaces can be joined fairly easily by using the simple trick of leaving part of the casting in both the internal and the external scans. The challenge was twofold: (1) capturing the full 360 degree shape of a soft part that cannot support itself, and (2) capturing the nternal anatomical features and non-uniform wall thicknesses. SINCS met the challenges of measurement difficulty and complex modeling of human forms.

Digital Assembly

Another new innovative scanning technique is digital assembly (see Figure 3), a technique that relies on capturing the way parts fit together physically. Parts are assembled, then reference markers are placed on the assembled parts. The locations of those markers are captured using photogrammetry or similar techniques. Each part is then separated and scanned individually, but the reference marks on each part are snapped into the coordinate system measured for the entire assembly. With the location markers, partscans pop into their proper place in the assembly, and the entire part can be easily scanned.

Photogrammetry

A recent major technological advance combines non-contact 3D scanners with photogrammetry systems. Photogrammetry relies on taking digital images of special coded markers from different viewpoints, and then cross-checking the different viewpoints against each other to form a highly accurate model. It is especially useful in scanning large parts or complex assemblies. Most standard 3D scanners rely on having significant overlap between each scan shot to align the two patches together. Without photogrammetry, there can be significant tolerance stacks and therefore losses in accuracy. Photogrammetry eliminates the need for overlap since scan patches pop into the coordinate system defined by photogrammetry markers.

"Balancing" and Scaling

Master patterns for ornate objects are often carved by hand. In many applications it is helpful to do the hand work at a different scale than the final part. In Figure 4, the sculptor got higher detail by working at a larger scale. The sculptor had the carving digitized and "balanced" into a mathematically symmetrical shape. The digital models were then scaled to 20 different sizes for manufacturing. Rapid prototyping was used to make a pattern for each of the varying sizes to be manufactured. 3D scanning saved the sculptor the time and cost of carving 20 different patterns by hand.

Summing it Up

With recent advances in 3D scanning, if you or your suppliers are using any of the mainstream 3D CAD systems available today, you are more than halfway there. 3D scanning technology has been tailored to mainstream CAD, resulting in unprecedented compatibility and broadened applications. 3D scanning realizes significant time and cost savings over traditional measurement methods and accelerates product development cycle times.

George Hatzilias is the CEO of 3DScanCo (Atlanta, GA). He was formerly the lab manager of the Rapid Prototyping and Manufacturing Institute (RPMI) at Georgia Tech.

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