LiDARchaeology - University of British Columbiagis.sites.olt.ubc.ca/files/2012/03/Waber-LiDAR-2013_02_27.pdf · LiDARchaeology: Archaeological GIS applications of airborne LiDAR data

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.