3D Modeling of Buildings: Outstanding Sites

3

3D Digitization by Laser Scanner

The technique of digitization by laser scanner is relatively new, especially when compared to the age of the photogrammetric surveying methods discussed in the previous chapter. Nevertheless, in a short period, lasergrammetry has become an effective tool, adapted to the 3D recording of a site, especially outstanding structures. This chapter examines the instruments required for this type of survey, and then describes the methods to implement in order to acquire and process data from laser scanners with a view to constructing 3D models in the form of point clouds.

3.1. History

Laser emission was carried out for the first time in 1960 by Theodore Maiman [MAI 60]. Its use in remote sensing soon followed with the measuring of the distance from the earth to the moon two years later [SMU 62] using the principle of lidar technology (light detection and ranging), which relies on the analysis of properties of a laser beam sent toward an emitter. The industrialization of this technique took off in 1964 with the Geodolite^1,2, produced by Spectra-Physics (Mountain View, California), which enabled the measurement of profiles by mounting the instrument on an aircraft attachment.

The technology gradually developed to all observation scales (equipment mounted on satellites or airplanes, or used from the ground) with evolutions mainly regarding acquisition frequency, the possibility of scanning surfaces and the increased instrumental range. At the end of the 1990s, ...