3D Scanning ProcessIs 3D scanning right for me, you may ask?

Well, it depends….  It depends on what you want to scan, why you want to scan it, and what you want to do with the data.

For those unfamiliar with 3D scanning, most scanning technologies operate on similar principles, and output similar types of data, however they vary greatly in size, price and performance.  For this discussion, we’ll focus on small to mid-range scanners that can scan coffee cup sized items up to small car sized items.

Scanning is great for capturing large amounts of data, particulary on complex objects that are not easily measured by hand.  Most scanners will output a point cloud, which is a series of data points consisting of X, Y, Z values in a given coordinate system.   For most applications, this raw data form is fairly useless.

A first level of post processing is the conversion of the point cloud into a polygonal mesh through some type of software.  This polygon mesh can then be saved as an STL file.  This is a far more useful format than a point cloud.  A clean STL, with no defects or holes, can be sent directly to a 3D printer or rapid prototyping system.  This STL file can also be used for two of the most common applications for scanning:  reverse engineering and computer aided inspection.

In regards to reverse engineering, there are two typical methods for generating CAD models from scan data:  rapid surfacing and parametric modeling.  Since most CAD systems cannot make direct use of polygonal data, a NURBS surface model or B-Rep solid needs to be generated from the underlying scan.  Rapid surfacing entails the development of a network of curves that form a grid of patch boundaries on which the subsequent surfaces will be based.  This method is excellent for getting complex organic or sculptural shapes into CAD.  For more mechanical or geometric parts, parametric modeling makes more sense.  Parametric modeling entails “cutting” the scan data into cross-sectional sketches, which are then used to generate extrusions, lofts and sweeps in a fasion similar to traditional CAD modeling.

So, if you have a fairly complex part that cannot easily measure by hand that you need to get into a CAD system, then 3D scanning may be a good option for you. 

It may also be a good option for you if you have a complex part that you’ve manufactured, and would like to validate for accuracy against the original CAD file.

Scanned data can be overlayed onto the CAD model in order to produce a color coded deviation map.  By setting an “in-tolerance” color, one can immediately see if a part is out of spec, and where the deviations occur.  Additionally, geometric features such as holes and slots can be extracted from the scan, and compared to their counter part on the CAD model.  All this can be done quickly and easily with the right software.  Finally, the results can be quickly posted to an electronic report for e-mailing, or printing.

Like scanning for reverse engineering, scanning for inspection works best on complex free-form shapes that are not easily measured by hand.  So, you wouldnt’ scan a metal plate with 4 holes in it, but you would scan a raw casting to ensure that you have enough stock for downstream machining operations.

For more information on 3D scanning applications, please see our web site:  www.3dscanningservices.net, send me an e-mail:  dan@neometrixtech.com, or call me at    888-696-7226   .