Laser Scanning Techniques

How you scan depends on what you want to scan.

Laser scanning is a relatively new way of scanning objects and landscapes. Examples of laser scanning can be found in archaeology and the film industry. For example, the creators of "Lord of the Rings" used laser scanning to turn the cave troll Marquette model into a 3D computer image for digital animation. Laser scanning techniques are faster, do not contact the subject/object, are more accurate, offer complete coverage and can be repeated. This makes them the best means of scanning available. There are a variety of techniques and applications for laser scanning, so it is best to review many before choosing the right one for you.

Instructions

1. Scan objects using a 3D scanner. 3D scanners take a complete 3D picture of an object or environment. For example, this could be a sculpted model used to visualize a movie character or a skull in archaeology. This can be done on site using a hand-held scanner or in a laboratory-office setting using a larger machine. With both means the object's picture is uploaded directly to a computer where it will be rendered into a 3D image. There are many 3D scanner techniques:

   Time-of-flight: the laser uses the time a laser pulse takes to reach an object to build a 3D picture.

   Triangulation: uses a camera, laser dot and a laser emitter to form a triangulated picture.

   Conoscopic holography: the laser beam and its reflection off the surface are passed through a conoscopic crystal then projected.

   Hand-held: uses a triangulation method to form a 3D picture.

   Structured light: shines a laser pattern of light on the object, then analyses how the object deforms the pattern.

   Modulated light: same as structured light except that the pattern of light continuously changes.

2. Scan specimens with a confocal laser scanning microscope. With this technique the microscope is able to take layered shots of the specimen in question. Scientists can use a simple fluorescence technique to dye the areas of specific interest or to separate areas that would otherwise look too similar. The images will be sent to a linked computer for rendering and analysis.

3. Scan landscapes using LIDAR. LIDAR stands for Light Detection And Ranging. This scanning technique uses laser pulses to remote sense topography and objects not easily seen by the human eye. In this instance it is similar to RADAR. This is useful for archaeological sites as a whole prior to excavation. For example, if the site is covered in forest or bracken, the use of LIDAR will give an accurate feel for the contours of the landscape, including archaeological features like mounds and ditches.

4. Use volumetric techniques such as computed tomography to scan the inside of objects. Otherwise known as a CT scan, the laser or X-ray produces a 3D image of the inside of an object or person. Other volumetric techniques include magnetic resonance imaging (MRI).

5. Scan barcodes with a laser barcode scanner. The scanner interprets a code using different thicknesses of black and white lines compared against pre-determined values. This technique can be applied to logistics and stock maintenance as well as for retail.

References

• Survey Mapping: Laser Scanning, Archaeology, Metadata...
• Laser Design: FAQs on 3D Scanning & Related