Digital Terrain Model, Slope, ALS by Jouko Vanne

Airborne laser scanning – a new method to geological mapping and research

Laser scanning techniques are rapidly spreading to geological surveying, mapping and research. Geologists are eager to include this new method in their toolbox as it is giving accurate elevation and position information regardless of light conditions, vegetation cover or small climate hinders, when compared to the traditional passive method of aerial stereo photographs based on more or less visible light. Airborne laser scanning is an active method where a spray of laser beams are sent to the terrain to illuminate the Earth’s surface and photodiodes to register the backscatter radiation with a remarkable accuracy. Laser beams find their way to the surface even through a considerably tight canopy of vegetation.

The National Land Survey of Finland has started the production of the new nationwide digital elevation model in 2008. The new digital elevation model is a two by two meter grid-model with the elevation accuracy of 0.30 meters. The material is recently made easily available to government’s research institutes and universities. Companies and municipal authorities can get the material for a fair production price.

The new accurate digital elevation data provide new applications as well as improve applications already in use. The new model and laser scanning data achieve savings and can accelerate several processes by a variety of users. In the future, laser scanning can be in use when excavating and quarrying geological raw materials with robotic technology. On-line rapid measuring and detection can also be done using this method. (www.geologinenseura.fi/geologi-lehti/2-2010/nenonen_et_al.pdf )
National Land Survey of Finland:

Laser scanning is a technology based on laser pulses transmitted by an active sensor, or a laser scanner, and on accurate location information.

Laser scanning data is typically used to produce elevation models, as the technique is particularly well suited for providing elevation data of the ground and covered areas, such as forests.

In addition to the elevation data of the ground, laser scanning also provides information about other objects on the ground, such as roads and trees. The laser scanning technology can be used for making inventories of forests and for preparing three-dimensional city models. (www.maanmittauslaitos.fi/en/node/3177 )