A talk to the UNCG Archaeology, Anthropology and Geography Societies / departments, April 2013

1. UNC Greensboro 5th April 2013
Beyond the Visible -
maximising the potential of airborne remote sensing data for
archaeological feature detection
Rebecca Bennett
Postdoctoral Associate, Wired! Lab
Art, Art History and Visual Studies, Duke University
rebecca.bennett@duke.edu
www.pushingthesensors.com

2. UNC Greensboro 5th April 2013
Historic landscapes and airborne remote sensing data

3. UNC Greensboro 5th April 2013
Image: Stonehenge, 1906 © English Heritage NMR
‘The surface of England is a document that has been written on and erased over
and over again; and it is the business of the archaeologist to decipher it’
OGS
Crawford 1953

4. UNC Greensboro 5th April 2013
Airborne Remote Sensing for Archaeology
Two types of features detectable from the air:
Direct
e.g. changes in topography
Proxy
e.g. changes in soil or
vegetation properties

5. UNC Greensboro 5th April 2013
Spot the features...
Direct
topographic
change
associated
with a
Neolithic
henge
monument
Knowlton Circles Complex, Dorset UK © NMR

6. UNC Greensboro 5th April 2013
National Mapping Programme, English Heritage
Mapping and
archaeological
interpretation of all archive
aerial photography from
1945 onwards
Began in the 1990s
By 2009 40% of England
mapped, 50% increase in
known sites
www.english-heritage.org.uk/professional/research/landscapes-and-
areas/national-mapping-programme/

7. UNC Greensboro 5th April 2013
Issues of vegetation cover
Cropmarks at a protohistoric site at Grézac, France
http://archaero.com/Arch%E9ologie-a%E9rienne.htm

8. UNC Greensboro 5th April 2013
Issues of seasonality
11 July 1989 25 July 1990
Etton, Peterborough UK, reproduced with kind permission of R Palmer

9. UNC Greensboro 5th April 2013
Timing Critical!
17 June 1976 – parts of two vertical photographs taken 6 seconds apart
Etton, Peterborough UK, reproduced with Kind permission of R Palmer

10. UNC Greensboro 5th April 2013
Information can only be captured when it is visible...
Region of higher stress sensitivity
Standard AP
Topography visible dependent of sun angle
and azimuth
Vegetation stress is best identified in non-
visible wavelengths (NIR)

11. UNC Greensboro 5th April 2013
Incorporating “New” technologies for Archaeological Survey
Direct Features (topographic change): Airborne Laser Scanning / Lidar

12. UNC Greensboro 5th April 2013
Welshbury Hillfort, Gloucestershire
Images courtesy of the Forestry Commission © Cambridge University ULM

13. UNC Greensboro 5th April 2013
Proxy Features (vegetation and soil change): Airborne Spectral Imaging
Digital Spectral Imaging
Many materials,
including vegetation
and soils, reflect more Standard AP
energy outside the
visible spectrum,
particularly in the NIR

14. UNC Greensboro 5th April 2013
Project Aims
Contribute to understanding of ‘new’ sensors non-arable landscapes
Why?
- Unique and challenging landscapes
- Overlooked in favour of arable areas
- Wealth of information about past human
environmental interaction
- Impact on modern landscape management
What?
- Proof of concept for archaeological
prospection using airborne laser
scanning and digital spectral data
How?
- Quantitative analysis of archive ARS
data

15. UNC Greensboro 5th April 2013
The Pilot Study Everleigh, Salisbury Plain, UK
Archive Airborne Data - Lidar data (1m resolution)
- Multispectral data (14 bands, 450- 980nm), January and May
- 4-band vertical AP, 2006 and 2007

16. UNC Greensboro 5th April 2013
All data sources
were assessed
against the baseline
of the Wiltshire
Historic
Environment
Record
(transcription of
archive aerial
photography) in two
ways:
Binary Visibility
and
% percentage
recovery of
individual features

17. UNC Greensboro 5th April 2013
Upavon, Salisbury Plain, UK - Mission (Almost) Impossible
4th March 2010 - Natural Environment Research Council, Airborne Remote
Survey Facility
- Lidar and spectral bespoke data acquisition
Earth Resistance Survey
Ground Penetrating Radar
Spectral survey
Soil Samples
Topography Survey
All contemporary to the flight

18. UNC Greensboro 5th April 2013
Spectral Data Lidar Data
Impact of
Visualisation
Techniques
Vegetation
Indices
Feature Profile
Analysis
Seasonal
Comparison
Digital Data Stack
Land use
Assessment

19. UNC Greensboro 5th April 2013
Existing Visualization Methods
Airborne Laser Scanning
1. Slope, aspect, curvature
2. Shaded relief modeling
3. Principle Components Analysis
4. Horizon modeling (Sky View Factor)
5. Local Relief Modeling
Bennett, R., Welham, K., Hill, R.A., Ford, A., 2012. A Comparison of Visualization Techniques for Models Created from Airborne Laser Scanned
Data. Archaeol. Prospect. 19, 41–48.

20. UNC Greensboro 5th April 2013
Bennett, R, K Welham, R A Hill, and A Ford. 2013. ‘Using Lidar as Part of a Multisensor Approach to
Archaeological Survey and Interpretation’. In Interpreting Archaeological Topography – Airborne Laser Scanning,
Aerial Photographs and Ground Observation, ed. D C Cowley and R Opitz, 198–205. Oxford: Oxbow Books.

21. UNC Greensboro 5th April 2013

22. UNC Greensboro 5th April 2013
Existing Visualization Methods
Airborne Spectral data
1. Individual bands
2. True and False Color composites
3. Principle Components Analysis
4. Vegetation Indices
5. Spectral Separability
Bennett, R., Welham, K., Hill, R.A., Ford, A.L.J., 2012b. The Application of Vegetation Indices for the Prospection of Archaeological Features in
Grass-dominated Environments. Archaeol. Prospect. 19, 209–218.

23. UNC Greensboro 5th April 2013

24. UNC Greensboro 5th April 2013

25. UNC Greensboro 5th April 2013
Comparison of Sensors

26. UNC Greensboro 5th April 2013
The traditional view: aerial imagery
2002 2004

27. UNC Greensboro 5th April 2013
Seeing More...
Airborne Laser Scanner (ALS): Hyperspectral sensor:
topographical features Proxy soil and vegetation change

28. UNC Greensboro 5th April 2013
Summary of findings
• Archive airborne lidar and spectral data can be used to identify
features in non-arable environments
• NIR region highly sensitive to vegetation change representing
archaeological features in both January and May
• More features seen in January than May, indicating that for
environments where vegetation is less prone to stress (i.e.
cropmark formation) off-season data collection may be of equal
or greater value to peak-season data
• Suite of visualization methods, assessed quantitatively to provide
a toolkit for the use of ARS data for archaeological prospection
• High complementarity of the sensors
http://www.pushingthesensors.com/publications

29. UNC Greensboro 5th April 2013
Research and Teaching at Duke
Airborne Remote Sensing of Exmoor National Park
3D Interactive environments for exploring ARS

30. UNC Greensboro 5th April 2013
Desk based assessment of lidar, historic maps and aerial photography
GIS Feature Records
Features assessed during fieldwork
http://sites.duke.edu/vms551ls_01l_s2013/student-blog/

31. UNC Greensboro 5th April 2013
3D Interactive Environments
Exploration, Education and Outreach
Immersive Duke DiVE
Web-based open-GL module

32. UNC Greensboro 5th April 2013
Thank you for listening!
For the PhD research thanks are also due to…
The Ministry of Defence and Defence Estates for facilitating
access, especially Richard Osgood & Martin Brown, Senior
Historic Environment Advisors &
Chris Waldren and Chris Maple DE Geospatial Services
Wiltshire HER and Roy Canham
NERC ARSF, FSF and GEF for data and equipment loans
The Superstar Field Team:
Dr Kayt Armstrong, James ABCD Bennett, Barney.B.Bennett, Kimberly Briscoe,
Roy Canham, Justine Cordingley, Katie Hess, Kuro Kuma Hess, Heather Papworth,
Matthew Sumnall, Rachel Stacey, Kate Ward, Matthew Webster and Sarah Yarnall
This research was supported by a Bournemouth University Doctoral Research Bursary
For the postdoc research thanks are also due to…
Exmoor National Park Authority, especially Rob Wilson-North, Lee Bray and Catherine Dove
The Wired! Lab
The David.L.Paletz Innovative Teaching Fund
The Exmoor Student Field Team:
Nathan Bellis, Jordan Noyes, Lindsey Mazurek, Kelsey Richards, Crystal Terry