LIDAR

Aerial LiDAR (Light Detection and Ranging) is a mapping technology which uses reflected laser returns from the earth’s surface to an aircraft with on-board laser scanner, GPS and IMU sensors to determine the precise elevation and geospatial location of the terrain, vegetation, and features.

With innovations such as Multiple-Pulse in Air (MPiA)
technology and increased pulse repetition rates, LiDAR is an accurate and cost-effective method for creating threedimensional topographical and bathymetric aerial maps and highly accurate surveys of both surface terrain elements and manmade structures.

Bathymetric lidar uses a blue-green laser, which penetrates clear water easily. Airborne bathymetric lidar deploys two lasers from an aircraft. Red laser measures the height of the sea surface since it does not penetrate the water, the blue-green laser measures the distance to the seabed. The time difference between the two laser returns gives the depth of water, after some sophisticated signal processing.
Bathymetric lidar works very well in depths up to about 50 metres, when the water is clear and the seabed is light-coloured, such as around coral reefs.