Satellite archaeology

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A presentation given by Anthony Beck at the Archpro workshop1 in Vienna. The workshop was instigated by the Ludwig Boltzmann Institute.This presentation covers the applications of satellite platforms for archaeological prospection and heritage management.

Text of Satellite archaeology

  • 1. Satellite ArchaeologyAnthony (Ant) BeckTwitter: AntArchIC ArchPro Workshop 1 - Airborne Remote SensingVienna - 30th November 2011School of ComputingFaculty of Engineering

2. Some background I dont like the term satellite archaeology 3. OverviewThe Satellite PlatformArchaeological ProspectionLandscape Survey in data poor environmentsExemplar: Homs, SyriaThe FutureConclusions 4. OverviewThere is no need to take notes:Slides Text http://dl.dropbox.com/u/393477/MindMaps/Events/ConferencesAndWorkshops.htmlThere is every need to ask questions 5. Characteristics of the satellite platformSensor Types Active and Passive 6. Characteristics of the satellite platformSynoptic Footprint and Spatial Resolution 7. Characteristics of the satellite platformSpatial Resolution - 20cm Aerial PhotographyDetailedmappingField backdropSmall area 8. Characteristics of the satellite platformSpatial Resolution - 1m IkonosDetailedmappingField backdropLarge area 9. Characteristics of the satellite platformSpatial Resolution - 30m LandsatLandscapemapping Soils Geology Vegetation Land use etcLong historyMulti-spectralMulti-temporal 10. Characteristics of the satellite platformSpatial Resolution - 30m Landsat (geology bands)Landscapemapping Soils Geology Vegetation Land use etcLong historyMulti-spectralMulti-temporal 11. Characteristics of the satellite platformTemporal Resolution 12. Characteristics of the satellite platformTemporal Resolution 13. Characteristics of the satellite platformSpectral Resolution 14. Characteristics of the satellite platformA large archive 15. Problems of the satellite platformAtmospheric Attenuation 16. Problems of the satellite platformTopographic Distortion 17. Problems of the satellite platformPixel Mixing 18. Problems of the satellite platformClassification 19. Characteristics of the satellite platformPerceived issues for archaeologistsCost Its perceived to be expensiveComplexity Its perceived to be complex tounderstand and processTemporal constraints Revisits are frequent. Times of collection are fixedThe Google Earth effect 20. Characteristics of the satellite platformMy issues with satellite applicationsA solution searching for a problem Does it have a place in well understoodlandscapes?Cropmarks Unless youve got lots of money, whywould you want to prospect for spatio-temporally ephemeral cropmarks with asensor with a large synoptic footprintEveryone focuses on prospectionat the expense of The Landscape Integrated Cultural ResourceManagement 21. Archaeological ProspectionWhat is the basis for detection 22. Archaeological ProspectionWhat is the basis for detection 23. Archaeological ProspectionWhat is the basis for detectionAt the small scale: The archaeological record can beconsidered as a more or lesscontinuous spatial distribution ofartefacts, structures, organicremains, chemicalresidues, topographic variations andother less obvious 24. Archaeological ProspectionWhat is the basis for detectionAt the large scale: The distribution is far from even, withlarge areas where archaeologicalremains are widely and infrequentlydispersed. There are other areas,however, where materials and otherremains are abundant and clustered.It is these peaks of abundance thatare commonly referred to as sites,features, anomalies (whatever!). 25. Archaeological ProspectionWhat is the basis for detectionDiscovery requires the detection of one or more siteconstituents.The important points for archaeological detection are: Archaeological sites are physical and chemical phenomena. There are different kinds of site constituents. The abundance and spatial distribution of different constituents varyboth between sites and within individual sites. These attributes may be masked or accentuated by a variety of otherphenomena. Importantly from a remote sensing perspective archaeological site donot exhibit consistent spectral signatures 26. Archaeological ProspectionWhat is the basis for detection 27. Archaeological Prospection What is the basis for detectionMicro-Topographic variationsSoil Marks variation in mineralogy andmoisture propertiesDifferential Crop Marks constraint on root depth andmoisture availability changingcrop stress/vigourProxy Thaw Marks Exploitation of different thermalcapacities of objects expressedin the visual component asthaw marksNow you see medont 28. Archaeological ProspectionWhat is the basis for detectionWe detect Contrast: Between the expression of the remainsand the local background valueDirect Contrast: where a measurement, which exhibits adetectable contrast with its surroundings,is taken directly from an archaeologicalresidue.Proxy Contrast: where a measurement, which exhibits adetectable contrast with its surroundings,is taken indirectly from an archaeologicalresidue (for example from a crop mark). 29. Archaeological ProspectionWhat is the basis for detection 30. Archaeological ProspectionWhat is the basis for detection 31. Archaeological ProspectionWhat is the basis for detection 32. Archaeological ProspectionWhat is the basis for detection 33. 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 isexhibitedThe image must be captured at the right time: Different features exhibit contrast characteristics at different times 34. Satellite images archaeologists useHigh spatial resolution opticalEssentially large footprint vertical photographsLower spatial resolution than aerial (0.5 4m)Panchromatic (higher spatial resolution)4 band multi-spectral (lower spatial resolution) Blue Green Red Near Infra-Red 35. Satellite images archaeologists useHigh spatial resolution opticalThats it. 36. Satellite images archaeologists useHigh spatial resolution opticalNothing more to sayreally 37. Satellite images archaeologists useHigh spatial resolution opticalWell theres a bit more Image sources Major providers (GeoEye, DigitalGlobe), archive and bespoke Declassified Cold War spy photography Before modern destructive modificationFree viewers Google, Yahoo, Bing No control over the data 38. Satellite images archaeologists useHigh spatial resolution optical WorldView - 2Has 8 bandsCost for standard 4 band + pan $17 per square kilometer 8 band + pan $32 per square kilometer Minimum order of 25 square kilometersCost for bespoke 4 band + pan $23 per square kilometer 8 band + pan $38 per square kilometer Minimum order of $1800 39. Satellite images archaeologists useHigh spatial resolution optical WorldView - 2New: good water penetrationNew: Yellowness (crop) New: Red-edge (crop) New: NIR (crop/biomass) 40. However, prospection is not everythingWhy use satellites when its already known! 41. However, prospection is not everythingLandscape surveyIts not just about finding stuff Its about placing it in a context where it can be usefulMost countries do not have mature cultural managementframeworks e.g. Homs region of Syria or Vidisha area of India Archaeological inventory is significantly biased towards large andprominent landscape features What about the rest of the landscape? 42. However, prospection is not everythingLandscape surveyThis is an inventory problem OK we need to do more prospection! Bring on the planes! NOIf we were to start from the beginning would we do it all thesame way again Learn from our experiencesThis is what I hope to show in the rest of the presentation 43. However, prospection is not everythingLandscape survey Types of surveyReconnaissance survey: (Detection) primarily designed to detect all the positive and negative archaeologicalevidence within a study area.Evaluation survey: (Recognition) to assess the archaeological content of a landscape using surveytechniques that facilitate subsequent field-prospection, statisticalhypothesis building or the identification of spatial structure. 44. However, prospection is not everythingLandscape survey Types of surveyLandscape research: (Identification) to form theoretical understanding of the relationships betweensettlement dynamics, hinterlands and the landscape itself.Cultural Resource Management (CRM): (Management andProtection) primarily designed for management of the available resources. CRMapplications are not necessarily distinct from other survey objectivesalthough they may be conducted as part of a more general informationcapture system.Improve Reconnaissance Survey and impact on all the others. 45. However, prospection is not everythingLandscape survey Desk Based Assessments 46. However, prospection is not everythingLandscape survey Desk Based AssessmentsSources that are normally considered for reference during aDBA are: Regional and national site inventories. Public and private collections of artefacts and ecofacts. Modern and historical mapping. Geo-technical information (such as soil maps and borehole data). Historic documents. Aerial photography and other remote sensing.How can satellite imagery help in data poor environments. 47. Landscape Survey in data poor environmentsEcological Setting Hinterland Ecofacts Sites Artefacts 48. Landscape Survey in data poor environmentsNature of the evidence DBA resources Regional and national site inventories. Archaeological inventory is significantly biased towards large andprominent landscape features Public and private collections of artefacts and ecofacts Not well documented Modern and historical mapping. Not available, or available at inappropriate scales Geo-technical information (such as soil maps and borehole data). Not available, or available at inappropriate scales Historic documents. ? Aerial photography and other remote sensing. 49. Landscape Survey in data poor environmentsUnderstanding what form of derivatives are required