3D Scanning creates a 3d representation of an object using multiple views of the object. The object is often illuminated with various types of light patterns to aid digitalization.

This can involve any number of cameras or light projection devices. There are also scanners that can use other forms of marking mechanism, but almost all commercial 3D scanners use some form of light.

The major options available are either using laser light, white light (presentation projectors) or multiple cameras setups. There is a bit of confusion about the different types of technologies, so this article hopes to give a high level over-view of the pro’s and cons of each technology.

Type Laser Scanning White Light Scanning Steroscopic Correspondence
Overview Use a laser light to mark the subject. Uses a white light projector like the ones used for power point presentations to mark the subject. Uses two or more cameras and no active lighting device
Examples Most 3D object scanners are laser based. Most 3D face or body scanners are white light based. They use either classic structured light or stereoscopic correspondence with light projection. Any 3D scanner that only uses a camera.
Key Weaknesses

Scan time tends to be at least 10 times slower than white light. Not ideal for scanning objects that may move, like humans or animals.

Scanning human faces. Even with eye safe lasers few people feel comfortable risking someone’s eye sight.

Having a light controlled environment is important, with brighter projectors this is less of an issue but you won’t be able to scan outdoors.

Projectors are higher cost than lasers

Ideal for medium sized objects.

Can be labor intensive to get even a few dozen point samples.

Doesn’t require light to mark the object, but finding corresponding points is difficult and imprecise.

Can requires many either multiple cameras or multiple camera images from different angles
Key Strengths

Can scan very small objects, and noise tends to be lower.

Can scan in areas where there are various amounts of ambient light control.  Calibration tends to be easier to use because of this.

Usually the best choice for industrial inspection and installed systems

Can scan over a million points fast, this is critical in many scanning applications.

Usually the best choice for scanning human beings as there’s a low risk of permanent eye damage and humans move during the scanning process.

It’s the only choice where setting up a projector and light isn’t possible.

Good getting specific points on large objects. (ie. Buildings)
Speed

Slow, multiple lasers can speed the process but generally 10x slower than equivalent white light systems

Generally on the order of 15+ seconds to minutes.

Very Fast

From milliseconds to under 15 seconds.

Scan time is fast, but processing time can be very slow.
Point Accuracy Good. Good.

Good with human assistance.

Automated systems tend to be error prone
Point Density

High but depends on time spent on scan.

Resolution tends to be even through out the scan.

High, and is fixed to projector resolution.

Often more dense along a particular axis.

Point density is varies with camera resolution
Noise Level Low Medium High
Object Size Good for small, medium or large objects but you often need different scanning hardware for each case.

Most off the shelf projectors are good for medium to large objects.

Custom projectors are needed for small objects

 Works the same for any sized objects

Another comparison is to use still cameras versus video cameras. The big difference is quality of scan versus scan speed. Both types of cameras can produce good scans. It’s simply a trade off between scan quality and scan speed. Still cameras tend to be greater than 10 mega-pixels while video cameras are 1-3 mega-pixels. Still cameras also tend to have greater image controls so the color quality is much higher.

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