Science underpinning archaeological detection: DART

School of ComputingFaculty of Engineering

DART – Archaeological detection

Anthony (Ant) Beck

Twitter: AntArch

Potential of satellite images and hyper/multi-spectral recording in archaeology

Poznan – 31st June 2012

Overview

• How do we detect stuff

• Why DART

• Going back to first principles

• DART overview

• Platforms

• Knowledge base – impact on deployment

Archaeological ProspectionWhat is the basis for detection

We detect Contrast: • Between the expression of the remains

and the local 'background' value

Direct Contrast:• where a measurement, which exhibits a

detectable contrast with its surroundings, is taken directly from an archaeological residue.

Proxy Contrast:• where a measurement, which exhibits a

detectable contrast with its surroundings, is taken indirectly from an archaeological residue (for example from a crop mark).

Archaeological ProspectionThese attributes may be masked or accentuated by a variety of other phenomena

http://www.youtube.com/v/UfOi_7Os7kA


Micro-Topographic variations

Soil Marks• variation in mineralogy and

moisture properties

Differential Crop Marks• constraint on root depth and

moisture availability changing crop stress/vigour

Proxy Thaw Marks• Exploitation of different thermal

capacities of objects expressed in the visual component as thaw marks

Now you see meNow you dont

Archaeological ProspectionSummary

The sensor must have:• The spatial resolution to resolve the feature

• The spectral resolution to resolve the contrast

• The radiometric resolution to identify the change

• The temporal sensitivity to record the feature when the contrast is exhibited

The image must be captured at the right time:• Different features exhibit contrast characteristics at different times

A multi-sensor environment:which includes ground survey and excavation

Why DART? Isn’t everything rosy in the garden?

Why DART? ‘Things’ are not well understood

Environmental processes

Sensor responses (particularly new sensors)

Constraining factors (soil, crops etc.)

Bias and spatial variability

Techniques are scaling!• Geophysics!

IMPACTS ON• Deployment

• Management

Why DART? Precision agriculture Using science to maximise crop return

Why DART? Precision agricultureOutlier values are being controlled

Why DART? Traditional AP exemplar

Why DART? Traditional AP exemplar

Significant bias in its application• in the environmental areas where it is

productive (for example clay environments tend not to be responsive)

• Surveys don’t tend to be systematic

• Interpretation tends to be more art than science

What do we do about this?

Go back to first principles:• Understand the phenomena

• Understand the sensor characteristics

• Understand the relationship between the sensor and the phenomena

• Understand the processes better

• Understand when to apply techniques

What do we want to achieve with this?

Increased understanding which could lead to:• Improved detection in marginal

conditions

• Increasing the windows of opportunity for detection

• Being able to detect a broader range of features

What do we do about this? Understand the phenomena

How does the object generate an observable contrast to it's local matrix?• Physical

• Chemical

• Biological

• etc

Are the contrasts permanent or transitory?

What do we do about this? Understand the phenomena

If transitory why are they occurring?• Is it changes in?

• Soil type

• Land management

• Soil moisture

• Temperature

• Nutrient availability

• Crop type

• Crop growth stage

What do we do about this? Understand the relationship between the sensor and the phenomena


Spatial Resolution


Radiometric resolution

determines how finely a system can represent or distinguish differences of intensity

Radiometric Resolution


Temporal Resolution


http://www.youtube.com/v/Nh-ZB5bxPhc

Spectral(?) Resolution

What do we do about this? Understand the processes better

So what causes these localised variations?• Local conditions structure how any

contrast difference is exhibited:

• Soil type

• Crop type

• Moisture

• Nutrients

• Diurnal temperature variations


Expressed contrast differences change over time• Seasonal variations

• crop phenology (growth)

• moisture

• temperature

• nutrients

• Diurnal variations

• sun angle (topographic features)

• temperature variations


Exacerbated by anthropogenic actions• Cropping

• Irrigation

• Harrowing

What do we do about this? Example from multi or hyper spectral imaging

DART - Collaborators

DART: Ground Observation Benchmarking

Try to understand the periodicity of change• Requires

• intensive ground observation

• at known sites (and their surroundings)

• In different environmental settings

• under different environmental conditions

DART: Ground Observation Benchmarking

Based upon an understanding of:• Nature of the archaeological residues

• Nature of archaeological material (physical and chemical structure)

• Nature of the surrounding material with which it contrasts

• How proxy material (crop) interacts with archaeology and surrounding matrix

• Sensor characteristics

• Spatial, spectral, radiometric and temporal

• How these can be applied to detect contrasts

• Environmental characteristics

• Complex natural and cultural variables that can change rapidly over time

DART: Sites

Location• Diddington, Cambridgeshire

• Harnhill, Gloucestershire

Both with• contrasting clay and 'well draining'

soils

• an identifiable archaeological repertoire

• under arable cultivation

Contrasting Macro environmental characteristics

http://prezi.com/_tntxlrctptg/dart-sites/

DART: Probe Arrays

DART: Field Measurements

Spectro-radiometry• Soil

• Vegetation

• Every 2 weeks

Crop phenology• Height

• Growth (tillering)

Flash res 64• Including induced events


Resistivity

Weather station• Logging every half hour

DART: Probe Arrays


Aerial data• Hyperspectral surveys

• CASI

• EAGLE

• HAWK

• LiDAR

• Traditional Aerial Photographs

DART: Laboratory Measurements

Geotechnical analyses

Particle size

Sheer strength

etc.

Geochemical analyses

Plant Biology

DART: Laboratory Measurements

Plant Biology• Rate of germination

(emergence)

• Growth analysis

• Number of Leaves

• Number of Tillers

• Stem length

• Total plant height

• Drought experiment

• A - Ci Curve

• Chlorophyll a fluorescence

• Soil and leaf water content

• Root studies

• Root length and density.

• Root – Shoot biomass ratio.

• Total plant biomass

• Biochemical analysis: Protein and chlorophyll analysis.

• Broad spectrum analysis of soil (Nutrient content) and C-N ratios of leaf.

DART

ERT

B’ham TDR

Imco TDR

Spectro-radiometry transect

DitchRob Fry

DART – exemplars

Hyperspectral (400-2500nm)

High resolution Vertical

ERT

B’ham TDR

Imco TDR

Spectro-radiometry transect

DitchRob Fry

DART – exemplars

Airborne Laser Scanning

Discrete Echo and Full Waveform ERT

DitchRob Fry

DART – exemplars

Obliques

UAV

ERT

B’ham TDR

DitchRob Fry

DART: Data so far - Temperature

DART: Data so far - Permittivity

TDR - How does it work• Sends a pulse of EM energy

• Due to changes in impedance, at the start and at the end of the probe, the pulse is reflected back and the reflections can be identified on the waveform trace

• The distance between these two reflection points is used to determine the Dielectric permittivity

• Different soils have different dielectric permittivity

• This needs calibrating before soil moisture can be derived from the sensors

DART: Data so far - Permittivity

Further analysis of permittivity and conductivity against rainfall

Linking the changes to the weather patterns

Comparisons can be made between• Soils at different depths

• Archaeological and non-archaeological features

• Different soil types at the different locations

Conversion to moisture content is also a priority

DART: Data so far – Earth Resistance

R

DART: Data so far – Earth ResistanceProbe Separation (m)

0.25 0.5 0.75 1

June 18.04742552 18.88545 18.896896 16.79403

July 19.13517794 17.15205 17.081613 15.01906

August #N/A #N/A #N/A #N/A

September 8.841189868 13.255 14.512463 15.53069

October 7.988128839 10.97714 12.217018 11.6229

June July August September October

0.25 18.0474255247753

19.1351779351603

0 8.84118986817586

7.98812883944877

0.5 18.8854489164087

17.1520465259726

0 13.2550009710624

10.9771430226832

0.75 18.8968963893818

17.0816126928928

0 14.5124626121635

12.2170179547229

1 16.7940349425365

15.0190573579995

0 15.5306917565003

11.6228978543617

7.5

12.5

17.5

Change of Contrast Factors with Seasons

0.250.50.75

Twin Probe Electrode

Seperation (m)

Co

ntr

ast

Facto

r (%

)

Difference in magnitude

DART: Data so far – Earth Resistance

Spectro-radiometry: Methodology

• Recorded monthly

• Twice monthly at Diddington during the growing season

• Transects across linear features

• Taken in the field where weather conditions permit

• Surface coverage evaluated using near-vertical photography

• Vegetation properties recorded along transect

• Chlorophyll (SPAD)

• Height

http://prezi.com/-oaoksqr09gx/dart-hyperspectral-the-driest-spring/

DART: Plant Biology

Lab experiments conducted in collaboration with Leeds Plant Biology in 2011 and repeated in 2012

From soils at Quarry Field

Soil structure appears to be the major component influencing root penetration and plant health

http://prezi.com/v5kahvg2zmyz/dart-plant-biology/

DART: Knowledge Base

http://prezi.com/ef_aud--i00t/dart-knowledge-base

DART: Communication

http://prezi.com/yo-pijkatt0a/dart-communication-infrastructure/

http://dartproject.info/WPBlog/



Open Data: Server (in the near future)

The full project archive will be available from the server

Raw Data

Processed Data

Web Services

Will also include

TDR data

Weather data

Subsurface temperature data

Soil analyses

spectro-radiometry transects

Crop analyses

Excavation data

In-situ photos ETC.

Why are we doing this – spreading the love

Why are we doing this – it’s the right thing to do

DART is a publically funded project

Publically funded data should provide benefit to the public

Why are we doing this – IMPACT/unlocking potential

More people use the data then there is improved impact

Better financial and intellectual return for the investors

Why are we doing this – innovation

Reducing barriers to data and knowledge can improve innovation

Why are we doing this – education

To provide baseline exemplar data for teaching and learning

Why are we doing this – building our network

Find new ways to exploit our data

Develop contacts

Write more grant applications

Discussion

SFM

Pushbroom

High resolution frame

Oblique and UAV

Topographic

From SFM

Full Waveform LiDAR

Detection

Hyperspectral (including thermal)

Spectral Analysis

Visualization

ERT and tomography

Complex data!

Plant Biology

Phenology

Differential growth parameters

Data mining (process from measurements)

Environmental

Soils

Temperature

Questions

Overview

There is no need to take notes:

Slides – http://goo.gl/ZHYaB

Text – http://goo.gl/osQZi or http://goo.gl/M5Eu1

There is every need to ask questions

The slides and text are release under a Creative Commons by attribution licence.

http://goo.gl/ZHYaB

http://goo.gl/osQZi

http://goo.gl/M5Eu1

Science underpinning archaeological detection: DART

Education

Transcript of Science underpinning archaeological detection: DART