DART - improving the science. Dublin 23022012

DART - Improving the scienceunderpinning archaeological detectionAnthony (Ant) BeckTwitter: AntArchDublin– 23rd February 2012School of ComputingFaculty of Engineering

Overview•How do we detect stuff•Why DART•Going back to first principles•DART overview•Data so far•Open Science

OverviewThere is no need to take notes:Slides –Text –http://dl.dropbox.com/u/393477/MindMaps/Events/ConferencesAndWorkshops.htmlThere is every need to ask questionsThe slides and text are release under a Creative Commons byattribution licence.

Archaeological ProspectionWhat is the basis for detection

Archaeological ProspectionWhat is the basis for detectionAt the small scale:• The archaeological record can be considered as a more or less continuous spatial distribution of artefacts, structures, organic remains, chemical residues, topographic variations and other less obvious modifications

Archaeological ProspectionWhat is the basis for detectionAt the large scale:• The distribution is far from even, with large areas where archaeological remains are widely and infrequently dispersed. There are other areas, however, where materials and other remains are abundant and clustered. It is these peaks of abundance that are commonly referred to as sites, features, anomalies (whatever!).

Archaeological ProspectionWhat is the basis for detectionDiscovery requires the detection of one or more siteconstituents.The important points for archaeological detection are:

Archaeological ProspectionArchaeological sites are physical and chemical phenomena

Archaeological ProspectionThere are different kinds of site constituents

Archaeological ProspectionThe abundance and spatial distribution of differentconstituents vary both between and within individual sites

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

Archaeological ProspectionImportantly from a remote sensing perspective archaeologicalsite do not exhibit consistent spectral signatures

Archaeological ProspectionWhat is the basis for detectionWe detect Contrast:• Between the expression of the remains and the local background valueDirect 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 ProspectionSummaryThe 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 exhibitedThe image must be captured at the right time:• Different features exhibit contrast characteristics at different times

Archaeological Prospection What is the basis for detection 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 marksNow you see me dont

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

Why DART? ‘Things’ are not well understoodEnvironmental processesSensor responses (particularly newsensors)Constraining factors (soil, crops etc.)Bias and spatial variabilityTechniques are scaling!• Geophysics!IMPACTS ON• Deployment• Management

Why DART? Precision agriculture

Why DART? Traditional AP exemplar

Why DART? Traditional AP exemplarSignificant 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 do about this? Understand thephenomenaHow does the object generate anobservable contrast to its localmatrix?• Physical• Chemical• Biological• etcAre the contrasts permanent ortransitory?

What do we do about this? Understand thephenomenaIf transitory why are theyoccurring?• 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 therelationship between the sensor and the phenomena

What do we do about this? Understand therelationship between the sensor and the phenomena Spatial Resolution

What do we do about this? Understand therelationship between the sensor and the phenomena Radiometric ResolutionRadiometric resolutiondetermines how finely a system canrepresent or distinguish differences ofintensity

What do we do about this? Understand therelationship between the sensor and the phenomena Temporal Resolution

What do we do about this? Understand therelationship between the sensor and the phenomena Spectral(?) Resolution

What do we do about this? Example from multi orhyper spectral imaging

DART - Collaborators

DART: Ground Observation BenchmarkingBased 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: Ground Observation BenchmarkingTry 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: SitesLocation• Diddington, Cambridgeshire• Harnhill, GloucestershireBoth with• contrasting clay and well draining soils• an identifiable archaeological repertoire• under arable cultivationContrasting Macro environmentalcharacteristics

DART: Field MeasurementsSpectro-radiometry• Soil• Vegetation • Every 2 weeksCrop phenology• Height• Growth (tillering)Flash res 64• Including induced events

DART: Field MeasurementsResistivityGround penetrating radarEmbedded Soil Moisture andTemperature probes• Logging every hourWeather station• Logging every half hour

DART: Field MeasurementsAerial data• Hyperspectral surveys • CASI • EAGLE • HAWK• LiDAR• Traditional Aerial PhotographsLow level photography• 1 photo every 30 minutes

DART: Probe Arrays

DART: Weather StationDavis Vantage Pro Weather station• Collects a range of technical data e.g. • Wind speed • Wind direction • Rainfall • Temperature • Humidity • Solar Radiation • Barometric Pressure• And derivatives • Wind Chill • Heat Index

DART ERT Ditch Rob Fry B’ham TDR Imco TDR Spectro-radiometry transect

DART: Laboratory MeasurementsGeotechnical analysesGeochemical analysesPlant Biology

DART: Data so far - Temperature

DART: Data so far - TemperatureUseful tool for• Scheduling diurnal thermal inertia flights• Calibrating the TDR readings

DART: Data so far - PermittivityTDR - 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 - PermittivityKey aims• Investigate the propagation of EM radiation in different soil conditions (e.g. temperature, magnetic permeability, moisture content, density) and identify the difference between archaeological residue and the surrounding soil matrix• Attempt to use geotechnical properties (e.g. particle size distribution, moisture content) to predict the geophysical responses of the different EM sensors used in aerial and geophysical work• Link the soil properties to local weather and other environmental factors to enable better planning for collection techniques

DART: Data so far - Permittivity

DART: Data so far - PermittivityFurther analysis of permittivity and conductivity against rainfallLinking the changes to the weather patternsComparisons can be made between• Soils at different depths• Archaeological and non-archaeological features• Different soil types at the different locationsConversion to moisture content is also a priority

DART: Data so far – Earth Resistance

DART: Data so far – Earth Resistancemethodology similar to that employed by Parkyn et al. (2011)Overview• data points • lie within the ditch feature • over the non-archaeological feature• find an average data value for the feature and the surrounding soilThe percentage difference between these two figures canthen be considered the amount of contrast within the testarea.The higher the percentage, the better the feature is able to bedefined.

DART: Data so far – Earth Resistance Probe Separation (m) 0.25 0.5 0.75 1June R 18.04742552 18.88545 18.896896 16.79403July 19.13517794 17.15205 17.081613 15.01906August #N/A #N/A #N/A #N/A Difference in magnitudeSeptember 8.841189868 13.255 14.512463 15.53069 Change of Contrast Factors withOctober 7.988128839 10.97714 12.217018 11.6229 20 Seasons Contrast Factor (%) 15 Twin Probe Electrode Seperation (m) 10 0.2 5 0.5 0.7 5 5 Septemb June July August October er 0.25 18.047426 19.135178 8.8411899 7.9881288 0.5 18.885449 17.152047 13.255001 10.977143 0.75 18.896896 17.081613 14.512463 12.217018 1 16.794035 15.019057 15.530692 11.622898

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

Spectro-radiometry: Methodology• Lab-based, background methodology • Soils • Soil samples taken along transect • Reflectance measured with varying moisture content • Vegetation • Vegetation samples taken during each field visit • Measured under artificial light under controlled conditions

Diddington transect 1: Spectroradiometry June 2011 0.12Rel 0.1ativ 0.08er 0.06efle 0.04ctan 0.02ce 0 400 500 600 700 Wavelength (nm) 27/06/2011 Archaeology 27/6/2011 Outside archaeology 14/06/2011 Archaeology 14/06/2011 Outside archaeology 08/06/2011 Archaeology 08/06/2011 Outside archaeology

Diddington transect 1: Spectroradiometry June 2011 0.4R 0.35ela 0.3tiv 0.25er 0.2efl 0.15ect 0.1anc 0.05e 0 350 450 550 650 750 850 950 1050 1150 1250 1350 1450 1550 1650 1750 1850 1950 2050 2150 2250 2350 2450 Wavelength (nm) 27/06/2011 Archaeology 27/6/2011 Outside archaeology 14/06/2011 Archaeology 14/06/2011 Outside archaeology 08/06/2011 Archaeolgy 08/06/2011 Outside archaeology

DART: Plant BiologyLab experiments conducted in collaboration with Leeds PlantBiology in 2011 and repeated in 2012From soils at Quarry FieldSoil structure appears to be the major component influencingroot penetration and plant health

DART: Knowledge Base

DART: Communication

The case for Open Science from Cameron Neylon

Open Data: Server (in the near future)The full project archive will be available from the server Raw Data Processed Data Web ServicesWill also include TDR data Weather data Subsurface temperature data Soil analyses spectro-radiometry transects Crop analyses Excavation data In-situ photos

Open Data: Server (in the near future)Also: Hyperspectral data Thermal imaging Full Waveform LiDAR UAV data collectionFormats Standard interoperable formatsLicences These are not complete Most data will be made available under an open re-use licence (see server) Creative Commons GPL

Why are we doing this – spreading the love

Why are we doing this – it’s the right thing to doDART is a publically funded projectPublically funded data should provide benefit to the public

Why are we doing this – IMPACT/unlocking potentialMore people use the data then there is improved impactBetter financial and intellectual return for the investors

Why are we doing this – innovationReducing barriers to data and knowledge can improveinnovation

Why are we doing this – educationTo provide baseline exemplar data for teaching and learning

Why are we doing this – building our networkFind new ways to exploit our dataDevelop contactsWrite more grant applications

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DART - improving the science. Dublin 23022012

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