User manual

33
How Our 3D Scanner Works
The Matter and Form 3D Scanner is a laser-based scanner. Laser scanners
work by shining a laser at an object, using a camera to capture data that is
returned from the laser hitting the surface of an object and then using software
to stitch all that data together. On the Matter and Form scanner, as the lasers
pass over the surface of an object, data is generated at a rate of approximately
2,000 points per second. This data is comprised of thousands of individual
points that record things like surface detail, distance from the camera, texture,
and color. These thousands of points, when viewed collectively, form a “point
cloud” that is a direct representation of the scanned object.
The scanner is very good at capturing organic shapes. Curves, surface detail
and outer geometry scan very well. Deep depressions and overlapping features,
however, are difficult for the scanner to capture accurately. For example, it
would be able to scan the outside of a drinking straw but not all the empty space
on the inside of the straw. Like a photo camera, the scanner can only capture
what is in its field of view.
The Importance of Calibration
In order to maximize the scanner’s precision and accuracy, it’s highly
recommended users devote time to calibration whenever the scanner has been
moved. Every scanner will have tiny, unique differences as a result of the
manufacturing process, temperature fluctuations and physical placement, so it is
necessary to allow the software to properly measure and compensate for such
differences (i.e., calibration).
Calibrating is especially important after a scanner is moved. All data captured by
the scanner are in relation to the dead center of the turntable. Because the
turntable can shift up to 1 mm, any potential shift can affect what the camera,
lasers and software consider to be the dead center of the turntable when
constructing a point cloud.
Throughout the calibration process the scanner’s camera, lasers and software
are developing reference points in an XYZ coordinate system based on the
geometries and angles of the calibration box and its checkered squares. Upon
completion, the software and firmware will save these reference points when
scanning all subsequent objects until calibration is completed again and new
reference points are saved.