Technical Information
How 3D scanning works
There are many different methods for capturing the 3D measurements of a physical part and thus, many different types of scanners. 3D Scan Solutions offers only Photogrammetry services at this time, though our future plans encompass a wider range of scanning services.
Photogrammetry
Photogrammetry is a technology based on standard photography and projective geometry and was originally used to digitize large objects such as buildings, oil rigs and warehouses. The principle behind photogrammetry is to take multiple images of objects and manually or automatically reference common points in each photograph. Points can be added automatically or manually to create 3D measurements of the desired elements of the part. Photogrammetry is often used with other 3D scanning technology to provide full surface measurements of parts and to retain tight tolerances over large areas.
3D Laser Scanning
3D Laser Scanning or 3D Laser Scanners can generally be categorized into three main categories - laser triangulation, time of flight and phase shift. These laser scanning techniques are typically used independently but can also be used in combination to create a more versatile scanning system. There are also numerous other laser scanning technologies that are hybrids and/or combinations of other 3D scanning technologies such as accordion fringe interferometry or conoscopic holography.
White Light Scanning
White Light Scanning (structured light scanning) is used to describe a wide range of 3D scanning devices. The basic technique is to project a known pattern of light (usually white) and use sensors (typically CCD cameras) to capture images of the object with the patterns projected on it. In order to capture 3D information, multiple patterns and/or multiple sensors can be used. If multiple patterns are projected, the software uses referencing and the change in shape of the known pattern to interpret 3D measurements. If multiple sensors are used the software uses the known pattern and referencing between image angles to determine the 3D measurements.
Coordinate Measuring Machines
Coordinate Measuring Machines, more commonly referred to as CMMs, are measuring devices that use movable probes. The position of the probe is tracked with a series of encoders along each axis of the machine. These encoders, referred to as digital measuring tape, can track the movement of the measuring probe to within nanometers with the only uncertainty in the measurement being the rigidity of the machine itself. CMMs are also known as touch-probes because the probe must "touch" the part to obtain a measurement. CMMs can be fixed mounted or portable, with portable CMM arms being more versatile but sometimes less accurate because they have a higher tendency to flex or lose calibration. CMMs can also be combined with non-contact scanning technology to capture full surface data.
Destructive Slicing
Destructive Slicing is a process in which multiple pictures of an object are taken from a fixed location. Thin slices of the object are removed between each image. The distance to the object is precisely controlled, therefore the scale of each image is known. After slicing all the way through the object, the images are stacked up in the capture software - resulting in a full 3D model of the object.