TECHNICAL INFORMATION ON LIDAR BATHYMETRY
 


Bathymetric Lidar systems operate in a manner that is similar to their Airborne Lidar Mapping (ALM) counterpart, with one notable exception. Bathymetric systems transmit two light waves, one in the infrared and one in the green spectrum, and are capable of detecting two returns that delineate the water surface and seabed. The infrared band is quickly absorbed and is therefore used to detect the water surface, while the green band is used as the optimum color to achieve maximum penetration in shallow water. Lidar bathymetry systems operate at a much slower rate, currently around 1000 soundings per second, due to the need to generate a much longer laser pulse and higher power requirements.

Bathymetry mapping is a stand-alone Lidar data product. Despite the high cost of acquiring an ALB system, the methodology offers significant savings both in operational cost and productivity increases, when compared to conventional survey methods. ALB mapping can be conducted in clear water in depths up to 50m. This of course is a function of water clarity and will decrease with increased water turbidity. ALB systems are generally flown from fixed or rotary wing aircraft, due to their size, weight and power requirements.


Technical Information:
Lidar
Lidar Bathymetry
SHOALS-1000T

Related Web Sites:
International Lidar Mapping Forum
Optech

Related Links:
SHOALS-1000T Brochure
SHOALS-1000T Spec Sheet
SHOALS-1000T Deliverables

 


SHOALS-1000T Operational Concept with WaveformBecause of the increased energy required to penetrate the denser medium of water, ALB systems operate at a much slower scan rate than terrestrial systems. Because a short, laser pulse would be scattered in the water column, bathymetry systems must use a much longer pulse. This is typically on the order of 250 nanoseconds as opposed to 10 nanoseconds for a topographic system. The pulse is generated as a digital waveform, making it easier to detect the smallest variances in the returns, including those perturbations in the water column. The infrared band is quickly absorbed and is therefore used to detect the water surface. The green band is used as the optimum color to achieve maximum penetration in shallow water.

Fugro's Airborne Lidar Bathymetry services utilize the SHOALS-1000T, which is based on the latest generation technology available today.

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