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WORKING WITH LIDAR DATA IN ARCGIS 10.1
Dave TewksburyDepartment of Geosciences
Hamilton CollegeClinton, NY
On the Cutting Edge Albuquerque 2013
Seeing the Earth in unprecedented detail.
On the Cutting Edge 2013
To assess risk and drive research
Toe Jam Hill fault scarp
Waterman Point scarp
beach uplifted
during 900 AD
earthquake
15 km west of Seattle
Haugerud, Weaver, and Harless (http://pugetsoundlidar.ess.washington.edu/About_LIDAR.htm)
On the Cutting Edge 2013
LiDAR – Light Distance and Ranging
Aircraft location known to within
few cm using GPS base
stations.Aircraft attitude determined by Inertial Measurement Unit.
Laser scans the surface at 100,000 to 200,000 pulses per second
Oregon LiDAR Consortium (http://www.oregongeology.org/sub/projects/olc/default.htm#use)
On the Cutting Edge 2013
15 - 20 cm
Direction of
Flight
GPS ReferenceBase Station
Laser
Laser PulseLaser
Spot Size
Scan Line
Crosby, Christopher, 2009 (opentopography.org/index.php/resources/education)
Travel time combined with known location and attitude of laser platform plus scan angle allows calculation of precise location of each return point.
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Variable(1 - 30 m)
Spot 1
Spot 2
Spot 3
Spot 4
Spot 5
Spot 9
Spot 17
Spot 25
Spot 12
Crosby, Christopher, 2009 (opentopography.org/index.php/resources/education)
LiDAR data
Aircraft flight results in laser scans in zig-zag pattern within swath. Points not arranged in a grid. Pulse rate high; point spacing commonly 1 m or less. Swaths overlap; data density highest in overlaps.
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Each laser pulse can produce multiple returns by reflecting off several surfaces in its path
red= 1st return yellow = 2nd return green = 3rd return
Oregon LiDAR Consortium (http://www.oregongeology.org/sub/projects/olc/default.htm#use)
Each return defines a point in space with a unique set of X-Y-Z coordinates
At left, point cloud view of tree, colorized by LiDAR return:
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Jason Stoker, USGS EROS
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Key Concept
Data is a Point Cloud with each point occupying a specific X, Y, Z position in 3D space
http://facility.unavco.org/software/idv/IDV_datasource_point_cloud.html
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Point Cloud with each point occupying a specific X, Y, Z position in 3D space
Point cloud symbolized by elevation
Florence Oregon LAS data downloaded from OpenTopography viewed in ArcGIS 10.1 with 3D Analyst extension On the Cutting Edge 2013
ASPRS Classification Codes
Class Meaning0 Never Classified1 Unassigned2 Ground3 Low Vegetation4 Medium Vegetation5 High Vegetation6 Building7 Noise8 Model Key9 Water10 Reserved for ASPRS Definition11 Reserved for ASPRS Definition12 Overlap13-31 Reserved for ASPRS Definition
Class numbers are not necessarily return numbers
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Hamilton College hillshaded raster
derived from first return points
Hamilton College hillshaded raster
derived from classified
ground points
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LiDAR Data Sources
http://www.opentopography.org/
The handout is a “cookbook” for processing the data
All the data is on the DVD which should be copied to the C drive
Work at your own pace and I’ll be around to answer questions/solve issues
You really cannot learn this by watching someone do it.
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NOAA Digital Coast LiDAR – Bathy data
Hillshade with semi-transparent orthophoto in ArcScene On the Cutting Edge 2013
http://www.jaypeakresort.com/skiing-riding/the-mountain
www.firsttracksonline.com
On the Cutting Edge 2013
