Aerial Archaeology in Ireland - The Heritage Council

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Satellites The potential for using satellite imagery in archaeology has been recognised for over ten years (Fowler 1996), though it is only in the last five years that the availability and cost of high-resolution imagery has made it an obvious alternative to aircraft-based vertical photography. As discussed below, and as with conventional aircraft, satellites can be used to provide imagery based on optical (visible light, near infrared, shortwave infrared), thermal and radio wavelengths. A range of satellites is used to provide such imagery. They are generally positioned at altitudes of 400km to 700km in polar, sun synchronous orbit, with a typical repeat overpass of one to 16 days. Depending on the particular satellite and the services offered, they can provide imagery at low resolution (c. 1km or more), medium resolution (c. 100m to 1km), high resolution (c. 5m to 100m) and very high resolution (c. 5m or less). Although medium resolution can provide valuable general vegetational mapping, it is the high (and more particularly very high) resolution systems that are of most value for archaeological applications, as outlined below. Available High Resolution Satellite Imagery (Source: M. Critchley, ERA-Maptec Ltd) Satellite Resolution (m) Bands Type QuickBird colour infrared (pan merge) 0.60m NIR, R, G Colour QuickBird multispectral 2.44m NIR, R, G, B Colour IKONOS colour infrared (pan merge) 1m NIR, R, G Colour IKONOS multispectral 4m NIR, R, G, B Colour Spot 5 (pan merge) 2.5m NIR, R, G Colour Spot 5 (pan merge) 5m NIR, R, G Colour Spot 5 (multispectral) 10m SWIR, NIR, R, G Colour Landsat ETM 15m SWIR, NIR, R, G Colour Radarsat 10m C-Band Radar ASTER 18m/30m SWIR, NIR, TIR Colour, Thermal Abbreviations for wavebands: SWIR = shortwave band infrared, NIR = near infrared, TIR = thermal infrared; R = red; G = green; B = blue; C-Band = C-band radar As noted earlier, the Google Earth internet site now offers basic cover of most of the world, but with blocks of much higher quality resolution of about 1-2m which can be of some use archaeologically. For Ireland, this imagery now covers major population centres and various other areas and swathes of landscape including, for example, a significant part of Kerry. It compares well with relatively high-level vertical photography. Very Low-level Aerial Imagery At the most detailed, low-level end of the scale, the use of remote-controlled cameras (less often other scanners) mounted on small, unmanned aircraft (i.e. balloons, kites and radio controlled model aircraft) or on top of manoeuverable poles and masts has been an established, though not mainstream, form of aerial archaeological photography since the 1970s. This continues to be developed by some practitioners, and is becoming increasingly refined as the technology of remote controlled photography and control of miniature flying platforms improves (e.g. Knisely-Marpole 2001 on kites; Schönherr 2001 on model aircraft). For example, in recent years, the Discovery Programme has been making good use of both balloons and telescopic masts (Figures 19, 20), though others said they had experimented with kites for site photography without much success. 43
44 Figures 20 a-b: The use of balloons for low-level aerial photography a: Acquisition of aerial imagery using a Skyshot kite/balloon on an excavation trench at Carns, Co. Roscommon (Discovery Programme Medieval Rural Settlement Project) b: Ortho-rectified balloon-mounted imagery created using Topcon PI- 3000 photogrammetry software (Discovery Programme Medieval Rural Settlement Project, 2007) Figure 21: Vertical photograph of a souterrain at Roestown, Co. Meath, on the route of the M3 motorway. This was taken using a remote controlled Nikon D2X camera on a Jeep mounted telescopic mast at a height of approximately 23m (Hawkeye Photography for Meath County Council/National Roads Authority and Archaeological Consultancy Services, 27 October 2006)
Page 1 and 2: A I R A N D E A R T H A E R I A L A
Page 3 and 4: © An Chomhairle Oidhreachta / The
Page 5 and 6: 3.9 Integration with other Types of
Page 7 and 8: Figure 14: The Discovery Programme
Page 9 and 10: Figure 39: This vertical photograph
Page 11 and 12: 10 Foreword One of the initiatives
Page 13 and 14: 12 Acknowledgements It would not ha
Page 15 and 16: 14 Key Priorities for Aerial Archae
Page 17 and 18: 16 • A practical handbook in arch
Page 19 and 20: 18 • A series of pilot studies co
Page 21 and 22: 20 5. Any new strategy for reconnai
Page 23 and 24: 22 As a means of discovering archae
Page 25 and 26: 24 Drawing on the work of O.G.S. Cr
Page 27 and 28: 26 2 PRINCIPAL SOURCES OF AIR PHOTO
Page 29 and 30: 28 National Museum of Ireland While
Page 31 and 32: 30 Other material held by the GSI i
Page 33 and 34: 32 Figure 9: An infrared vertical i
Page 35 and 36: 34 The aims and objectives of these
Page 37 and 38: 36 2.5 Private Collections Dr Daphn
Page 39 and 40: 38 2.6 Commercial Collections Two w
Page 41 and 42: 40 Figure 18: Google Earth satellit
Page 43: 42 3.2 Aerial Platforms The equipme
Page 47 and 48: 46 Figure 23: The true form of the
Page 49 and 50: 48 Figure 25: The cumulative impact
Page 51 and 52: 50 3.4 Conventional Photography: Di
Page 53 and 54: 52 Vertical versus Oblique Photogra
Page 55 and 56: 54 Metrical Survey As Doody observe
Page 57 and 58: 56 shoreline and topography (ground
Page 59 and 60: 58 The fieldwork showed that the ge
Page 61 and 62: 60 Sonar Bathymetry Although there
Page 63 and 64: 62 Both Kelleher (1995) and Redfern
Page 65 and 66: 64 Interpreting Chronology and Sequ
Page 67 and 68: 66 While the Archaeological Survey
Page 69 and 70: 68 County No. Ringforts No. identif
Page 71 and 72: 70 Figure 36: Newly identified crop
Page 73 and 74: 72 Figures 38 a-b: Contrasts in urb
Page 75 and 76: 74 Roles and potential for historic
Page 77 and 78: 76 4.2 Roles in Supporting Archaeol
Page 79 and 80: 78 Figures 41 a-b: Gillian Barrett
Page 81 and 82: 80 The Archaeology of Lakes, Coast
Page 83 and 84: 82 Whole Landscape Approaches Perha
Page 85 and 86: 84 Figure 45: Drumlin landscape nea
Page 87 and 88: 86 Roads The National Roads Authori
Page 89 and 90: 88 Pipelines The general principles
Page 91 and 92: 90 General Development Where there
Page 93 and 94: 92 ‘…numerous sites in pasture
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94 • • Earthen monuments are co
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96 Designed Landscapes and Conserva
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98 showing the clear benefits of in
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100 Figure 55: Aerial photograph of
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102 5 QUALITY, RESOURCES AND ORGANI
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104 Estimates of costs per site or
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106 ago in England, may have meant
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108 6 TEACHING AND TRAINING 6.1 Cov
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110 6.2 Other Provisions for Traini
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112 Benson, D and Miles, D 1974. Th
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114 Doody, M G, 1995. ‘Ballyhoura
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116 Twohig and M. Ronayne (eds) Pas
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118 Raftery, J, 1951. Prehistoric I
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120 Colin Shell Cambridge Universit
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Aerial Archaeology in Ireland - The Heritage Council

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