Application of Multi-Sensor Remote Sensing for Flood Protection Planning Over the Sajó Valley

Airborne laser scanning (LIDAR)

LIDAR is an optical remote-sensing technique that uses laser light to scan the surface of the earth, producing highly accurate spatial data (Figure 1). LIDAR, primarily used in airborne laser mapping applications, is emerging as a cost-effective alternative to traditional surveying techniques such as photogrammetry. The major hardware components of a LIDAR system include a collection vehicle (aircraft, helicopter, vehicle, and tripod), laser scanner system, GPS (Global Positioning System), and INS (inertial navigation system). An INS system measures roll, pitch, and heading of the LIDAR system.

LIDAR is an active optical sensor that transmits laser beams toward a target while moving through specific survey routes. The reflection of the laser beam is detected and analyzed by receivers in the LIDAR sensor.

Laser pulses emitted from a LIDAR system reflect from objects both on and above the ground surface: vegetation, buildings, bridges, and so on (Figure 2).

Aerial digital imagery (orthophoto production)

The perspective images without distorsions are called orthophotos. When they are digital they are called digital orthophotos. If the images are referenced into a coordinate system, then we talk about orthophoto maps or digital orthophoto maps. The first step in digital orthophoto production is to take aerial photographs of the land surface. The orthophotos are the final product after the cutting of georeferenced, orthorectified and moisiacked images.

Aerial hyperspectral imagery

The aim of aerial hyperspectral imagery is to collect data with high information content and field resolution about our environment. Therefore one such image may be suitable for determining material or biophysical properties that would not be possible using traditional aerial imagery. This is due to the fact that a hyperspectral sensor collects data in a much wider wavelength band, so it includes ranges invisible to the human eye (Figure 3).

Until recently hyperspectral applications stayed within the limits of research, nevertheless nowadays more sand more practical uses of aerial hyperspectral imagery appear in the field of botany, agriculture, environmental protection, military, disaster management and other fields requiring detailed environmental data.