OSi Airborne Terrestrial LIDAR INFOMAR Annual Seminar … LiDAR for coastal... · National Mapping Agency OSi Airborne Terrestrial LIDAR INFOMAR Annual Seminar 2013 University of

National Mapping Agency

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OSi Airborne Terrestrial LIDAR

INFOMAR Annual Seminar 2013

University of Limerick 9th October 2013

Ciaran Bruton

Remote Sensing Operations Manager

Ordnance Survey Ireland


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OSi & INFOMAR

• GSI request to OSi Nov 2011

• Difficulty in capturing data in shallow water for INFOMAR

• Requirement to provide airborne terrestrial LiDAR

• To be captured at Low Water Spring Tide

• 3 priority areas and 26 priority bays identified

• Shannon Estuary initial priority

• Fitting in with OSi National Height Model Remit


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Light Detection And Ranging

• A remote sensing technology

that uses laser scanning to collect height data.

• The Laser emits a light pulse, the time taken for the light to return to the sensor is recorded, giving the distance between the object and the sensor


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Flying Operations

• Based in Ennis R/O

• Flying out of Shannon airport

with Westair

• Two adapted Piper Aztecs

– Laser Scanner ALS50

– Digital camera ADS80


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Laser Scanner

• ALS 50

– 150 kHz pulse rate

– MPIA

– 4 return range detection

system

– Inbuilt IMU

– Airborne GPS Receiver

– Nighttime capability


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Flight Planning

Project Requirements – Low Water Spring Tides

– 2 hour window for low water time

– 3 day window for Spring Tide

– ASCII 1m 1k tile in IG

Project Set Up – Point Density 2 per m²

– Flying Height = 1500m

– Swath = 800m

– Cover at least 1k inland


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Aircraft Configuration

Pilot

Display

GPS

Antenna

Camera/Se

nsor

Operator

Controls


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GPS Referencing


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Post Mission

• Storage devices

removed from aircraft

• Data downloaded in

Ennis office and sent to

Dublin HQ


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Post Processing

• Raw data downloaded to server

• Basestation GPS is combined with

airborne GPS and IMU data to

generate flight line trajectory

• Trajectories applied to raw data to

create georeferenced point-cloud

• Point-cloud contains all laser hits in a

default layer


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Point Classification

• Obvious blunders removed

• Macro run to generate ground

model

• Cross sections run to further edit

and correct ground model

• Vector mapping, stereo images

and intensity images used to

assist

• Only raised objects now left in

default layer

• Further classification carried out

to building and/or vegetation

layers to create DSM’s


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Digital Terrain Model (DTM)


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DSM (Digital Surface Model)


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Output & Verification

• Irregular point cloud output to

regular lattice grid

• Lattice grid output to ASCII,

ESRI Grid etc

• Cluster of ground control

points selected on hard

surfaces

• Ground control heights

compared to laser heights and

verification report created


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Shannon Estuary 1


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Shannon Estuary 2


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Intensity Image


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Isometric View


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Webcam JPG


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Current Project Status • Flying

– Commenced Feb 2012

– 5 bays/areas completed • Shannon Estuary, Waterford, Dungarvan,

• Ballyferriter/Murreagh, Caherdaniel/Waterville

– 6 bays/areas in progress • Shannon Mouth, Wexford, Clonakilty,

• Dingle, Skibbereen/Crookhaven,

• Killary/Mannin

– 1800 km² approx.

• Processing – 5 bays/areas delivered

• Shannon Estuary, Waterford, Dungarvan,

• Ballyferriter/Murreagh, Caherdaniel/Waterville

– ASCII 1m 1k tiles in IG

– Estimated water line

– Webcam JPG’s


www.osi.ie

Thank You

OSi Airborne Terrestrial LIDAR INFOMAR Annual Seminar … LiDAR for coastal... · National Mapping Agency OSi Airborne Terrestrial LIDAR INFOMAR Annual Seminar 2013 University of

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