LiDARchaeology: Archaeological GIS applications of airborne LiDAR data Nick Waber UBC Department of Anthropology February 27 th 2013 UBC GIS Users Group
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LiDARchaeology:Archaeological GIS applications of airborne
LiDAR data
Nick WaberUBC Department of Anthropology
February 27th 2013UBC GIS Users Group
LiDARchaeology:Archaeological GIS applications of airborne
LiDAR data
● LiDAR principles and practices– a very brief intro to LiDAR
● Archaeological Applications of LiDAR● My work with LiDAR● Open LiDAR: online data sources and
opensource software
What is LiDAR?
Light
Detection
And
Ranging
● Focused beams of light (lasers) are directed at a surface
● The time it takes for the light to be reflected a sensor is measured
● The resulting data is used to determine the distance between the sensor and the target
● Dense beam clusters and multiple pulses and returns may be measured
Why is LiDAR useful?
● Fast
● Unaffected by difficult terrain
● Very precise (~5-20cm spatial precision)
● Able to get past the vegetation canopy
LiDAR collection
● Terrestrial– Pulses generated and
measured using a tripod-mounted unit
– Georeferenced via GPS
– Covers a relatively small area
– Can produce the most dense, precise point clouds
● Airborne– Pulses generated and
measured from an airplane-mounted unit
– Georeferenced via GPS
– Can cover large swathes of land very quickly
LiDAR collection
● Airborne– Pulses generated and
measured from an airplane-mounted unit
– Georeferenced via GPS
– Can cover large swathes of land very quickly
NOAA 2012
What is included in a LAS file?
Primary features:– XYZ point cloud
– Return number
– Classification number
– Intensity values
XYZ Point cloud
XYZ Point cloud
XYZ Point cloud
Pulse Return Number
● Multiple pulse returns from reflection off multi-tiered vegetation
● Last pulse return is ground level
● Pulse return differentials permit point classification (next slide...)
NOAA 2012
Classification Number
● 0 never classified● 1 Unclassified● 2 Ground● 3 Low vegetation● 4 Medium Vegetation● 5 High Vegetation● 6 Building
(and more)
Classification Number
● 0 never classified● 1 Unclassified● 2 Ground● 3 Low vegetation● 4 Medium Vegetation● 5 High Vegetation● 6 Building
(and more)
Intensity
©Google 2013
LiDAR Applications
● Forestry
● Petro Industry
● Hydrology
● Disaster Management
● Engineering
● Prospectors
● Archaeologists
Archaeological Applications of LiDAR
● Site survey and identification● Site and feature mapping● 3D modelling and visualization
Site/Feature Survey and Identification
From Chase et al. 2011
● Foliage-concealed surface features may be revealed on high-resolution bare earth models
● No machetes required
Site/Feature Survey and Identification
Images courtesy of Fraser Valley Archaeological Project, SRRMC, SFU, UBC
Site/Feature Survey and Identification
© FVRD 2008
Total Station Map of Village site. Fraser Valley Archaeological Project:Sts'ailes, SFU, UBC, SRRMC
Site/Feature Mapping
Site Modelling and Visualization
Site Modelling and Visualization
LiDAR in the field: Belize
● Chase et al. 2011– Caracol, Belize
– ~200 km2 survey
– Identified new structures, causeways, and LOTS of terraces
– More territory surveyed in 3 weeks than in the previous 85 years
LiDAR in the field: England
● Challis et al. 2011– Intensity data analysis
– Prospecting for ancient landforms in river valleys
– ID paleochannels and earthworks
LiDAR in the field: Mexico (Chiapas)
● Rosenwig et al. 2013– Izapa: Chiapan
piedmont region
– Identified previously unkown mounds
– Refined early topographic surveys
– Moving on to precise mound alignments
LiDAR in the field: Mexico (Chiapas)
My work with LiDAR
● 3D virtual reality– High-resolution DEMs
for high-res imagery
– Integrated feature reconstructions
– Immersive environments...?
The (open) tools of the trade
● SAGA GIS– Free, opensource
– Excellent LAS handling
– Good point cloud control
– Great surface interpolation options
– Easy to learn
– Only Linux/Windows
The (open) tools of the trade
● GRASS GIS– Free, opensource
– Extremely feature-rich
– Great 3D visualization
– Lots of online support
– Mac OSX, Linux, and Windows compatibility
– Steep learning curve
– LAS handling is... complicated
The (open) tools of the trade
● Quantum GIS (QGIS)– Free, opensource
– Intuitive GUI
– Loads of plugins
– GRASS integration
– Lots of online support
– Easiest to learn
– Mac OSX, Linux, and Windows compatibility
– No native LAS handling
Where to get LiDAR data (for free)
● Global: http://www.redarrowmaps.co
m/lidarportal/
Where to get LiDAR data (for free)
● USA: http://www.opentopography.org/
Where to get LiDAR data (for free)
● Oregon: http://www.oregongeology.org/dogamilidarviewer/
● Puget Sound: http://pugetsoundlidar.org/● Idaho: http://www.idaholidar.org/
Where to get LiDAR data (for free)
● BC: http://www.nanaimo.ca/ortho/
● Nova Scotia: http://agrg.cogs.nscc.ca/resources/imagery/LiDAR
● Canada...?
Where to get LiDAR data (for free)
● Global: http://www.redarrowmaps.com/lidarportal/ ● Global: https://www.lidar-online.com/product-list.php
● USA: http://www.opentopography.org/
● USA: http://www.csc.noaa.gov/digitalcoast/data/coastallidar
● BC: http://www.nanaimo.ca/ortho/
● Oregon: http://www.oregongeology.org/dogamilidarviewer/
● Puget Sound: http://pugetsoundlidar.org/● Idaho: http://www.idaholidar.org/
● Other links: http://www.laszip.org
References
Challis, Keith, Chris Carey, Mark Kincey, and Andy J. Howard
2011 Airborne Lidar Intensity and Geoarchaeological Prospection in River Valley Floors. Archaeological Prospection. 18:1-13.
Chase, Arlen, Diane Z. Chase, John F. Weishampel, Jason B. Drake, Ramesh L. Shrestha, K. Clint Slatton, Jaime J. Awe, and William E. Carter
2011 Airborne LiDAR, archaeology, and the ancient Maya landscape at Caracol, Belize. Journal of Archaeological Science. 38:387-398.
National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center
2012 Lidar 101: And Introduction to Lidar Technology, Data, and Applications. Revised. Charleston, SC: NOAA Coastal Services Center.
Rosenwig, Robert M., Ricardo López-Torrijos, Caroline E. Antonelli, and Rebecca R. Medelsohn
2013 Lidar mapping and surface survey of the Izapa state on the tropical piedmont of Chiapas, Mexico. Journal of Archaeological Science. 40:1493-1507.
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