1 October 2003
The maximum angle allowable from nadir should be specified. Other technical consid-
erations that will affect the quality of the resulting imagery include: What sun angle is
allowable? What lens focal length is allowable? What altitude will the collection be
flown? Will the imagery be flown at several resolutions or just one? Who will do the
orthorectification and mosaicing of the imagery? Will DEMs, DTMs, or DSMs be used in
the orthorectification process? How will unseen and shadow areas be treated in the final
product? When planning airborne acquisitions, these questions should be part of the deci-
3-9 Bathymetric and Hydrographic Sensors.
a. The Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS
ric mapping. The Joint Airborne Lidar Bathymetry Technical Center of Expertise
(JALBTCX) is a partnership between the South Atlantic Division, US Army Corps of
Engineers (USACE), the Naval Meteorology and Oceanography Command and Naval
Oceanographic Office and USACE's Engineer Research and Development Center.
JALBTCX owns and operates the SHOALS system. SHOALS flies on small fixed wing
aircraft, Twin Otter, or on a Bell 212 helicopter. The SHOALS system can collect data on
a 4-m grid with vertical accuracy of 15 cm. In clear water bathymetry can be collected at
23 times Secchi depth or 60 m. It does not work in murky or sediment-laden waters.
Corps uses vessels
equipped with acoustic transducers for hydrographic sur-
veys. The USACE uses multibeam sonar technology in channel and harbor surveys. Mul-
tibeam sonar systems are used for planning the depth of dredging needed in these shallow
waters, where the accuracy requirement is critical and the need for correct and thorough
calibration is necessary. USACE districts have acquired two types of multibeam trans-
ducers from different manufacturers, the Reson Seabat and the Odom Echoscan multi-
beam. The navigation and acquisition software commonly in use by USACE districts is
HYPACK and HYSWEEP, by Coastal Oceanographics Inc. For further information see
security restrictions this site can only be accessed by USACE employees).
3-10 Laser Induced Fluorescence.
a. Laser fluorosensors detect a primary characteristic of oil, namely their characteris-
tic fluorescence spectral signature and intensity. There are very few substances in the
natural environment that fluoresce, those that do, fluoresce with sufficiently different
spectral signatures and intensities that they can be readily identified. The Laser Environ-
mental Airborne Fluorosensor (LEAF) is the only sensor that can positively detect oil in
complex environments including, beaches and shorelines, kelp beds, and in ice and snow.
In situations where oil contaminates these environments, a laser fluorosensor proves to be
invaluable as a result of its ability to positively detect oil