The disadvantage is poor performance.
Mobile laser scanning (MLS)
Mobile Laser Scanning (MLS) is performed by moving a vehicle-installed scanner. Mobile scanning system can be mounted on cars, ships, railroad cars and other vehicles. The technique allows for a limited short-term stay in closed environments (travel under bridges, short tunnels). MLS is ideal for urban areas.
The technique is used for high-accuracy mapping and 3D-modeling of linear infrastructure (roads, railways, power lines, streets), complex and highly-detailed structures (settlements, junctions and multi-level overpasses, rocky shore, the downstream pool of dams (with boats), and so on. The accuracy is 5-8 cm, the detailed drawing is 1-5 cm, and the capacity is up to 500 linear km of imagery per day (bandwidth imagery is 50-250 m).
The disadvantages: roofs are not available for scanning; the objects (like fences, bushes) next to the vehicle can be obstacles.
Airborne laser scanning (ALS)
Airborne Laser Scanning (ALS) is a leading technology for a rapid, highly accurate and efficient method of simulation and 3D visualization of large areas in the scale 1:500 -1:5000. The accuracy is 5-8 cm, the detailed drawing is 20-50 cm, and the capacity is up to 800 linear km of imagery per day (bandwidth imagery is 1000-1500 m). It is usually accompanied by a simultaneous digital aerial survey with a resolution of 5-15 cm in visible and NIR band. They are exceptionally compact, lightweight and cost effective, and are designed to meet the most challenging requirements in airborne surveying. It is applied in urban areas, industrial plants, engineering, and mission planning and project management for rough and inaccessible regions.
The disadvantages: low accuracy when scanning vertical surface (e.g. walls).
These techniques can be combined to eliminate the disadvantages of each other. The outlined disadvantages are considered in relation to every technique, but even the slowest technique (the terrestrial laser scanning) is much more productive than tachometric survey, and the less accurate technique (airborne scanning) is more detailed, accurate and faster than aerial survey.
- Topographic maps and GIS layers.
- High-precision digital elevation model (DEM) and terrain model (DTM).
- 3D-object model (CAD, 3D MAX, DGN), including a texture.
- Different size and dimension of sheets.
- Profile, cross sections of objects.
- Virtual terrain model and overflights.
- Colored clouds of laser reflection points (on simultaneous photo).
- "Reticular" object model is used to restore stucco, unique objects (monuments, technological elements of constructions) (only for TLS).
- Facade and floor plans (for TLS).
- Orthophotos in the visible, infrared, or thermal bands (for ALS);
- Perspective aerial photos (for ALS).