Transcript
Airborne Bathymetric Lidar Systems and the Challenge of Water Turbidity
The Optech Solution
Maxime Elbaz, President Optech Inc. © Copyright 2013, Optech. All rights reserved. E&OE.
May 9, 2014
Growing Need for Coastal Information Over 40% of the world’s population and ¾ of all urban centers are in or near the coastal environment
Understanding near shore habitats is critical for management decisions, disaster planning, environmental impacts and the challenges from growing populations and rising sea levels. © Copyright 2013, Optech. All rights reserved. E&OE.
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Fundamental Questions Why do we need Airborne Bathymetric Lidar systems? Where do we need Airborne Bathymetric Lidar systems?
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The Coastal Water Clarity Challenge
Diffuse Attenuation Coefficient (K (Kd)*
* Based on Spring 2013 NASA Aqua-MODIS space satellite derived diffuse attenuation coefficients (Kd) at 490nm and recalculated at 532nm © Copyright 2013, Optech. All rights reserved. E&OE.
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Concept of Topographic Lidar
GPS
INS
H (Xg,Yg,Zg)
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Concept of Bathymetric Lidar
Assumptions Sea surface is static Homogenous water column Illuminated sea floor is assumed lambertian
Atmospheric losses
H 400 m Sea surface
(a+bb), ß(p ), bf, m
h Seafloor
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© Copyright 2013, Optech. All rights reserved. E&OE.
© Copyright 2013, Optech. All rights reserved. E&OE.
CZMIL System Laser Rack Operator Rack
Lidar Sensor Head
Digital Camera (16MP)
Control Rack
Thermal Rack
Hyperspectral Camera (CASI-1500)
2012-14: Four awards for best bathy technology
Designed by Optech for the U.S. Army Corps of Engineers, US Navy and USGS and in collaboration with the University of Mississippi © Copyright 2013, Optech. All rights reserved. E&OE.
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CZMIL System Sensor Fusion: Integrates several sensors
Data Fusion: HydroFusion software fusing Lidar, hyperspectral, and digital camera data
3D Environmental seamless topo and bathymetry system enabling bottom classification & water column characterization and object detection © Copyright 2013, Optech. All rights reserved. E&OE.
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CZMIL Concept of Operation 140 kts
400 m
~300 m
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CZMIL Enabling Technology One Laser for Deep and Shallow Water Depth Measurement • • • • •
Laser power: 30 W (532nm) High pulse rate: 10KHz Laser pulse length: 2.0ns Aperture: 20 cm Fast PMT receiver
Field of view for the Deep Channel receiver (40mrad)
Laser spot (2.9m on water surface)
Field of view for the Shallow Channel receiver (1.9mrad)
Topo & Shallow water:
Deep water: 10,000 soundings per sec.
70,000 soundings per sec. © Copyright 2013, Optech. All rights reserved. E&OE.
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CZMIL Night Flight Video (5/7/2012)
14 © Copyright 2013, Optech. All rights reserved. E&OE.
CZMIL Survey in Clear Water
Maui, Hawaii © Copyright 2013, Optech. All rights reserved. E&OE.
CZMIL Survey in Clear Water
Depth 45 meters
Maui, Hawaii © Copyright 2013, Optech. All rights reserved. E&OE.
CZMIL Survey in Clear Water
Ocean Jeju Island, Korea © Copyright 2013, Optech. All rights reserved. E&OE.
Mouth of River
CZMIL Survey in Clear Water
River bottom Jeju Island, Korea
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Power line
CZMIL Survey in Clear Water
South Sea, Korea © Copyright 2013, Optech. All rights reserved. E&OE.
CZMIL Survey in Clear Water
Power lines
Fish cages
South Sea, Korea
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CZMIL Survey in Turbid Water
Water Conditions off the MS Gulf Coast in US Digital Camera image 20cm resolution © Copyright 2013, Optech. All rights reserved. E&OE.
Turbid Water Lidar Waveform
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Sharp Waveforms Matters
Smoothed and sharp waveform generation is critical to improve accuracy of depth and penetration in optically deep/turbid water. © Copyright 2013, Optech. All rights reserved. E&OE.
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CZMIL Unique Capabilities in Turbid waters Key parameters for optically deep (turbid) waters and muddy seafloors Specific hardware design High Laser Power Short pulse length Big aperture mirror Fast response receiver
Higher valid point density
Clear and smoothed waveforms ABL Waveforms from shallow turbid water can be generated by well defined optical design, good receiver characterizations and noise reduction techniques
Water Turbid Algorithm module to extract depth information from muddy bottoms
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CZMIL Survey in Turbid Water Turbid Water Module Performance
Transition point from traditional to mud bottom detection
Depth of ~ 2-4m in the newly detected areas
Mississippi Gulf Coast, US
Increase in coverage with the Turbid Water algorithm. Kd ~ 0.8 – 1.5 © Copyright 2013, Optech. All rights reserved. E&OE.
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CZMIL Survey in Turbid Water Turbid Water Module Performance
Draining channel from Lake Calumet
Boundary showing the area with sediments Boundary showing the area contaminated
Draining channel from Lake Calumet, US. Courtesy of USACE © Copyright 2013, Optech. All rights reserved. E&OE.
CZMIL Survey in Turbid Water Turbid Water Module Performance
Depth of ~12m in the newly detected areas Kd >0.3
With Turbid Water Module
Spatial profile plot: Green = with mud bottom detection Red = without Draining channel from Lake Calumet, US. Courtesy of USACE
Color coded elevation image © Copyright 2013, Optech. All rights reserved. E&OE.
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Mapping bathy data with bottom features. Korea Kd>0.2 with depth >25m. Courtesy of KHOA
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CZMIL Bathymetric System - Conclusion
CZMIL system with the new Turbid Water Module enables use of airborne bathymetric lidar for turbid and muddy waters, which are 80% of populated coastal zones.
CZMIL in operational use for critical coastal management decisions by several US and Foreign Government Agencies in a variety of water conditions and depths
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[email protected]
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