Post on 12-Feb-2018
National Mapping Agency
www.osi.ie
OSi Airborne Terrestrial LIDAR
INFOMAR Annual Seminar 2013
University of Limerick 9th October 2013
Ciaran Bruton
Remote Sensing Operations Manager
Ordnance Survey Ireland
National Mapping Agency
www.osi.ie
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
National Mapping Agency
www.osi.ie
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
National Mapping Agency
www.osi.ie
Flying Operations
• Based in Ennis R/O
• Flying out of Shannon airport
with Westair
• Two adapted Piper Aztecs
– Laser Scanner ALS50
– Digital camera ADS80
National Mapping Agency
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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
National Mapping Agency
www.osi.ie
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
National Mapping Agency
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Aircraft Configuration
Pilot
Display
GPS
Antenna
Camera/Se
nsor
Operator
Controls
National Mapping Agency
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GPS Referencing
National Mapping Agency
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Post Mission
• Storage devices
removed from aircraft
• Data downloaded in
Ennis office and sent to
Dublin HQ
National Mapping Agency
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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
National Mapping Agency
www.osi.ie
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
National Mapping Agency
www.osi.ie
Digital Terrain Model (DTM)
National Mapping Agency
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DSM (Digital Surface Model)
National Mapping Agency
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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
National Mapping Agency
www.osi.ie
Shannon Estuary 1
National Mapping Agency
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Shannon Estuary 2
National Mapping Agency
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Intensity Image
National Mapping Agency
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Isometric View
National Mapping Agency
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Webcam JPG
National Mapping Agency
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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
National Mapping Agency
www.osi.ie
Thank You