3D Scanning

3d_laser_scanner 3D Scanning technologies have been around for a long time – longer in fact than 3D Printing itself. 3D Scanning involves the use of a device (called a 3D scanner ) that analyzes a real-world object or environment to collect data on its shape.  The data gathered may also include information about its appearance (i.e. color). The collected data can then be used to construct digital, three dimensional models.

There are many many different approaches and technologies associated with  3D scanning, although these days  (because of the abundance of photographic devices in our every day lives), much of the research and most of the advances (at least for consumer based 3D scanning technologies) seem to be focused around photometric scanning systems.

3D Scanning Technologies

This section provides a very brief outline of some of the main classes of 3D scanning technology :

Contact 3D Scanning

Contact 3D scanners probe the subject through physical touch.  A “probe” of some sort – often via an articulated arm, comes in direct contact with the object to be scanned and precise measurements are taken of the 3d dimensions of the object.  This type of scanning is not usually suitable for scanning delicate or valuable objects such as historical artifacts as it can be destructive. Contact 3D Scanning is also relatively slow compared to the other scanning methods

Non Contact Active 3D Scanning

Active scanners emit some kind of radiation or light and detect its reflection or radiation passing through object in order to probe an object or environment.

3d_hand_scannerTime-of-flight

Time-of-flight 3D laser scanning uses laser light to probe the subject.  A laser is used to emit a pulse of light and the amount of time before the reflected light is seen by a detector is measured, and the distance to the surface can be precisely measured. A laser rangefinder only detects the distance of one point in its direction of view, so, a series of rotating mirrors are typically used to change the direction of view to scan different points.Typical time-of-flight 3D laser scanners can measure the distance of 10,000~100,000 points every second.

Hand-held laser scanners

Hand-held laser scanners create a 3D image through a triangulation method: a laser dot or line is projected onto an object from a hand-held device and a sensor  measures the distance to the surface.

Structured light

artec-3d-scanner

Structured-light 3D scanners project a pattern of light on the subject and look at the deformation of the pattern on the subject.

Modulated light

Modulated light 3D scanners shine a continually changing light at the subject. A camera detects the reflected light and the amount the pattern is shifted by determines the distance the light traveled.

Computed tomography (CT Scan)

is a medical imaging method which generates a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images.

Magnetic resonance imaging

..  another a medical imaging technique that provides much greater contrast between the different soft tissues of the body than computed tomography (CT) does, making it especially useful in neurological (brain), musculoskeletal, cardiovascular, and oncological (cancer) imaging.

Non Contact Passive 3D Scanning

Passive scanners do not emit any kind of radiation themselves, but instead rely on detecting reflected ambient radiation.  Passive methods can be very cheap, because in most cases they do not need particular hardware and can often use simple, readily available digital cameras.

  • Stereoscopic scanning systems usually employ two video cameras, slightly apart, looking at the same scene. By analyzing the slight differences between the images seen by each camera, it is possible to determine the distance at each point in the images.
  • Photometric scanning  systems usually use a single camera, but take multiple images under varying lighting conditions. More sophisticated, multi-camera photometric scanning system (like the setup from Infinite Realities below)  are able to undertake full 360° object scans in a split second, and can also capture colour information about the object (which is ideal for 3D printing)
  • Silhouette scanning techniques use outlines created from a sequence of photographs around a three-dimensional object against a well contrasted background. With these approaches some concavities of an object (like the interior of a bowl) cannot be detected.

115xDSLR - Single shot - Full body Scanning system by Infiniote realities