Introduction Laser scanning is a lot like photography. A 3D scanner is a device that analyzes a real-world object or environment to collect data on its shape and possibly its appearance for example colour. The collected data can then be used to construct digital, three dimensional (3D) models useful for a wide variety of applications. While a camera collects colour information about surfaces within its field of view, 3D scanners collect distance information about surfaces within its field of view.
The “picture” produced by a 3D scanner describes the distance to a surface at each point in the picture. It is important to realize that these machines work on a line of sight. It will almost always take more than one scan to get a complete picture of a room. These scans have to be brought in a common reference system, a process that is usually called alignment or registration, and then merged to create a complete model. This whole process, going from the single range map to the whole model, is usually known as the 3D scanning pipeline.
History and Development of Laser Scanning System The history of laser technology is over 40 years old; lasers have been knownfor over 30 years and used in practical applications for more than 25 years. The scientific basis of laser technology lies in the realm of atomic physics,more strictly speaking, foundations were laid by the Danish physicist NielsBohr (1913 – theory of the structure of the hydrogen atom) and the GermanAlbert Einstein (1916 – introduction of the concept of stimulated emission) [1, 2]. In 1950, A.
Kastler from France proposed optical pumping (creation ofchanges in the distribution of filling of different atomic energy levels as aresult of excitation by light radiation) which earned him the Nobel Prizein physics in 1966 . In the years 1953 to 1954, American scientists from Columbia Univer-sity, Ch. H. Townes and J. Weber, and Soviet researchersN. G. Basov andA. M. Prokhorov, working independently at the Lebedev Institute of Physics,proposed the application of stimulated emission to amplify microwaves. Forthis achievement, Townes, Basov and Prokhorov received the Nobel Prize inphysics in 1964 [1-10].
In 1954, Townes, together with co-workers J. Gorgon and H. Zeiger,applied the concept in practice, utilizing ammonia as the active mediumand building the world’s first wave amplifier in the microwave range (emit-ting radiation of wavelength 12. 7 mm) which they calledmaser. This term isderived from the acronym of Microwave Amplification by Stimulated Emission of Radiation. In 1958, Ch. H. Townes and A. L. Schavlov predicted the possibility ofbuilding a maser for light radiation but the first attempt at its construc-tion in 1959 was unsuccessful . In 1981, A. L.
Schavlov received theNobel Prize in physics for his overall contribution to the development of lasers This document presents a personal history of Laser-Scan, as remembered by Paul Hardy (former Chief Programmer, then Product Manager and Principal Consultant) who joined the company as a programmer in 1975, and stayed until the company collapsed in 2003. It includes material from Peter Woodsford (former Managing Director and Chairman) who also joined in 1975. The descriptive section is followed by a list of milestones. Descriptive History Foundation and first product
Laser-Scan was founded in 1969 by three academics from the Cavendish Laboratories (the Physics department of the University of Cambridge). The senior of the three was Professor Otto Robert Frisch, FRCS, a very eminent physicist. Among his claims to fame was that he coined the names ‘chain reaction’, and ‘nuclear fission’ in a paper which laid down the fundamental theory that led to the atom bomb and to nuclear reactors for power generation. The ‘Prof’ (as he was always known) was an Austrian Jew who had moved to Denmark ahead of the German invasion of Austria, and then again to England, where he took on British nationality.
He was a true polymath. As well as being one of the foremost theoretical physicists of his generation, he was a very practical engineer. He could have made his living as a concert pianist. He spoke six languages fluently (German, Yiddish, Danish, English, French and Russian) and cound read several more, including Spanish and Arabic. He was a witty conversationalist and after-dinner speaker and overall was a kind and helpful man. I feel that it was a privilege to have known him.
The other two academics were John Rushbrooke (who remained at the Cavendish, running their research group on subatomic particles) and Graham Street (who became the first Managing Director of Laser-Scan). The academics had built in the laboratory a prototype of a machine called Sweepnik that used a laser beam, moved around by mirrors, to follow lines on photographs. These photos were of bubble chamber experiments to identify the elementary particles (protons, neutrons, electrons, etc. ) which are the building blocks of matter. People from other research institutes saw the prototype Sweepnik at the Cavendish, and wanted to buy one.
Eventually the academics raised financial backing and started the firm of Laser-Scan in 1969 to produce Sweepniks. The first Sweepnik shipped to Helsinki in 1972, and was followed by sales to many othercountries including France, America, Belgium, India, Japan, Greece, Egypt, etc. While, Laser scanner technology was introduced in the 1990s when in 1995 Cyra produced its first laser scanner. A laser scanner uses a pulsed laser, that produces up to 1,000 distinct, individual points (or surface geometry measurements) in each columnar sweep and then measures the time-of-flight for each point.
To do so with millimetre accuracy, the scanner is equipped with a timing device that measures picoseconds. Cyrax can also focus a narrow beam and maintain a small point size over long distances. The scanner captures four pieces of information for each individual point (surface geometry measurement): the x, y, z coordinates and a return intensity, this information is then used to map a colour or grayscale over the cloud. The image that appears on the computer screen is a 3D cloud, which, depending on the scan density and technologies used, can capture minute details.
The 3D laser scans and the point-cloud processing software apply colours to a point cloud and creates an instant 3D shrink-wrap computer image. This image looks like a 3D photograph – the 3D image can be reviewed from any perspective. Visualization via the shrink-wraps, while very useful, is only one of the capabilities offered by Cyclone. As soon as scanning is finished, a user can click on any two points within the point cloud and obtain immediate distance measurement between the two selected points. Once the point clouds are registered together, designers use software to process the data into CAD models of the existing structures.
The Leica HDS4500 used at the Federal Courthouse in Chicago, used special targets to align all the scans. Some of them were simple paper printouts but others were magnetic paddles made to keep an absolute center while they could be rotated in different directions to keep the target facing the scanner as it move through a space. To really make sure that to have enough information about where the targets are, take extra detailed scans of the target area. A dot is place on the place they are on screen and command the computer to acquire them. The result will gives this image This is home made laser scan Stock laser medical images
A high definition surveying scanner for environment Leica HDS4500 on loan from the Feds, laser scanning Logan Square park in Chicago Screenshot from the free David Laser scan program z-scanner handheld Heritage scanning project Example of the line of sight nature of 3D scanning, the image that cannot be seen also cannot be model. References Wikipedia article: http://en. wikipedia. org/wiki/3D_scanner http://www. leica-geosystems. com/hds/en/lgs_5210. htm http://www. faro. com/content. aspx? ct=us&content=pro&item=5 https://www. nextengine. com/indexSecure. htm http://www. david-laserscanner. com/ http://www. imodeller. com/en/