© Copyright 2004. Optech Incorporated. All rights reserved

© Copyright 2004. Optech Incorporated. All rights reserved.


Airborne Laser Technology for Hydrography and Coastal Mapping

(LIDAR)

Grady Tuell, Ph.D.

ftp://moray.dms.usm.edu/beyond_navigation_workshop


• Introduction to Optech

• Introduction to SHOALS

• Characterization of SHOALS performance• Depth accuracy• Depth penetration• Horizontal accuracy

• Beyond Safety of Navigation• Auto-extraction of shoreline• Topo/bathy visualizations• Active bottom images (pseudoreflectance)• 3D Benthic Mapping• Water Column Data


Introduction to Optech


Optech: 30 years of LIDAR technology

Optech Incorporated

Space and atmospheric Industrial

Laser Imaging

Terrestrial MarineOptech

International


ALTM and SHOALS pulse repetition rates

1

10

100

1000

10000

100000

1000000

1984 1988 1992 1996 2000 2004

0.01 MW

500 MW


Global Deployment of Optech Airborne Systems

1. Japan Coast Guard

2. JALBTCX

3. Fugro Pelagos


Introduction to SHOALS


Near shore

Niche: shoreline Niche: shoreline andand shallow water shallow water

SHOALS-1000T

Deep waterOn shore


• 1-kHz hydro laser•4 mJ @ 532 nm•3 mJ @ 1064 nm

• 9-kHz topo laser•6 uJ @ 1064 nm

• 4-channel receiver•10 cm aperture

SHOALS-1000T Sensor


SHOALS-1000T Consoles

Power Distribution

Laser Power Supply

Laser Electronics

Laser Chiller

18” LCD Display

Mirrored RHDs

Compact Flash

(Or Floppy Drive)


SHOALS: Typical Installation


SHOALS: Operational Concept

0

20

40

60

80

100

120

140

1 21 41 61 81 101 121 141 161 181

time (ns)

ph

oto

ele

ctr

on

s


4 Waveforms per Pulse

0

20

40

60

80

100

120

140

160

1 51 101

151

201

251

301

351

401

451

020406080

100120140

1 51

101

151

0

50

100

150

200

1 51 101

151

010203040506070

1 26 51 76

IR Surface Raman

APD Green PMT Green


Design Scan Pattern


Altitude

(m)

Swath

(m)

Lateral Spot Spacing

(m)

Forward Spot Spacing

(m)

Flight Speed (knots)

Scanner Cycle Rate

(Hz)

Area Coverage (nm2/hr)

400 60 2 2 124 16.0 4.0 300 60 2 2 124 15.9 4.0

400 130 3 3 127 10.9 8.9 300 125 3 3 128 11.0 8.7

400 215 4 4 126 8.1 14.7 300 165 4 4 162 10.5 14.5

400 230 5 5 180 9.2 22.4

Scan Patterns for Hydrographic Mode


Performance Characterization

Depth Measurement Accuracy

Underwater Horizontal Accuracy

Depth Penetration


SHOALS 1000T Specifications

• Measurement Rate - - hydro

- topo• Measurement Depth• Depth Penetration• Operating Altitude• Aircraft Speed• Laser Spot Spacing• Swath Width• Measurement Accuracy• Airborne System Weight

1000 Hz9 kHz50 m

kD > 3 (daytime)

200 - 400 m

125 - 175 knots

2x2, 3x3, 4x4, 5x5 m

up to 0.58 x altitude

IHO Order 1

210 kg


SFOTC – Ft. Lauderdale (8/03)


1 2 3 10 4 9

5 6 7 8

11

Extinction depth = 39m


Acoustic depths – SHOALS depths

10386 points; mean difference = 0.145m; sigma = 0.188m


IHO-1 Depth Accuracy (95% confidence)

Depth (m)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 10 20 30 40 50

)*13.0()5.0( 22 d


Underwater Horizontal Accuracy

Ten 2x2x2 m cubes were placed in the project area


Underwater Horizontal Position Accuracy

• Example waveform for 2m cube in 26m depth


Multiple detections of a 2m cube at 18m depth

• Grid is 1m x1m

• Yellow and Black squares are averages of 14 eastbound and westbound flights

• Separation of averages is 1.3 meters

eastbound westbound

Avg eastbound Avg westbound


Depth Penetration Test

0

20

40

60

80

100

120

140

0 50 100 150 200 250 300 350 400 450 500

PMTReal and simulated pulses:

Kd=0.085 m-1; Albido=0.62

real signal

simulated signal

real signal

simulated signal

0

20

40

60

80

100

120

0 50 100 150 200

APDReal and simulated pulses:

Kd=0.085 m-1; Albido=0.62

real signal

simulated signal

real signal

simulated signal

Courtesy of Viktor Feigels (Optech Int.) and Alan Weideman (NRL)


Extinction depth = 39m

Diffuse Attenuation Coefficient:

Kd = 0.09 m-1

Extinction Depth = 39m

Kd * D = 3.5


Beyond Safety of Navigation

Auto-extraction of shoreline

Topo/bathy datasets

SHOALS seafloor images (pseudoreflectance)

3d Benthic mapping and water column data


MLLW Shoreline

MHW Shoreline

Private uplands

Inland Waters; Tidelands

Territorial Seas; EEZ; and High Seas

Shoreline Mapping is a 3-D problem


Seal Rocks

( Courtesy of Jason Woolard at NOAA/NGS )

LIDAR-derived MHW Shoreline (ALTM)


Topo/bathy datasets

Ft. Lauderdale

Beach Front


SHOALS Bottom Images (pseudoreflectance)


Pseudoreflectance

sec),,(2

2

20

)(

cos)( kDsn

w

rPTr e

DHn

AFPmP

020406080

100120140

1 51

101

151


44 flightlines

APD/PMT merged at 12 m

13 Km x 3 Km

6.8 M points

5.0 m pixels

Max D = 37 m



Laser Data Spectral Data+ =

3D Coastal Landcover and Benthic information

Water column information

Active/Passive Fusion


SHOALS-1000TH

D,

La

Ls

Lb


CASI-2 LwaterHomogeneous areas in

SHOALS pseudoreflectanceCASI-2 K

Spatial Variation in Water Column


Spectrometer 534 SHOALS 532 DEPTH

Signal level fusion yields 3 data sets for classification


SHOALS Fusion Software

SHOALS

spectrometer

waveforms

waveforms

waveforms

depth

radiance

FU

SIO

N P

roce

ssor

SHOALS

Lbottom

Lwater

k


Example: Kaneohe Bay, Hawaii


3-d Benthic Habitat Mapping

Orange = SandGreen = SeagrassViolet = Uncolonized PavementYellow = Colonized PavementBrown = Macroalgae (50-90%)Blue = Macroalgae (10-50%)Black = Not Classified


Evolution of SHOALS

SHOALS-T

UAV

Higher Resolution

3D Environmental

Mapping

Documents

© Copyright 2004. Optech Incorporated. All rights reserved