Airborne LIDAR: high resolution shallow water bathymetric mapping
Abstract
The primary goals of the National Center for Airborne Laser Mapping (NCALM) include collecting research quality airborne LIDAR observations for projects funded by NSF through proposal/peer review, and improving airborne LIDAR technology/products to enable new applications. To extend NCALM capabilities to shallow water bathymetric mapping, as inexpensively and quickly as possible, we contracted for the development of a new sensor head compatible with the electronics rack of our near infrared (NIR) sensor, but operates at a wavelength of 0.532 micrometers. The new sensor head utilizes the same laser pump diodes, control electronics, waveform digitizer (currently 8 bit, with a 12 bit unit under development), and high capacity data storage units as the NIR sensor, but the optics are designed and coated for the green light produced by the frequency doubled NdYAG laser. The green sensor has a sufficient field of view to receive returns from the surface of a body of water, and allowing for refraction, from the underlying terrain. The laser operates at selected pulse rates up to 70 kHz, and has a nominal pulse width of approximately 5 nanoseconds. Laboratory and initial engineering field tests indicate that the system can detect bottom returns in 10 meters or greater depths of water with 0.1 loss of signal per meter of water and a bottom reflectivity of 0.1, and that it should be possible, with proper processing of the digitized waveform data, to resolve surface and bottom returns in water as shallow as 10 to 15 cm. Operating from an altitude of 400 meters hundred meters, ground-speed of 80 meters per second, scan angle of 15 degrees, and a pulse rate of 70 kHz, yields a single-pass point density of about 5 points per m2, which will yield bathymetric maps of shallow lakes, streams and coastal waters with previously unavailable spatial resolutions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.G11B..01C
- Keywords:
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- 1223 GEODESY AND GRAVITY / Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions;
- 1294 GEODESY AND GRAVITY / Instruments and techniques;
- 1694 GLOBAL CHANGE / Instruments and techniques;
- 1824 HYDROLOGY / Geomorphology: general