**2. Satellite remote sensing in archaeology**

This section introduces current remote sensing satellite data which are available for archaeo‐ logical research along with a historical background of remote sensing applications in archae‐ ology. As well, satellite sensors, such as Landsat, EO – Hyperion, QuickBird, IKONOS, etc., are also briefly outlined.

#### **2.1. Historical review**

The first aerial photographs used for archaeological purposes were taken just before the be‐ ginning of World War I in UK and Italy (Capper, 1907; Parcak, 2009; Bewley et al., 1999; Riley, 1987). Mesopotamia and the Levant were traditionally photographed until the 1940s (see Keneddy, 1925; Crawford, 1923, Glueck, 1965, Keneddy, 2002). After the end of World War II, new archaeological sites were explored due to aerial reconnaissance during the war. The scientific interest has been currently shifted to the Middle and Far East, as well as other areas in Europe and America (Parcak, 2009). During the Cold War in the 1960's, several sat‐ ellites, including CORONA, Argo, Lanyard and COSMOS, were used for military purposes. However, these data were only accessible after their declassification in 1995 (Parcak, 2009).

Spatial resolution of CORONA spy images taken during the Cold War could reach up to 0.6m (Lock, 2003). Fowler & Fowler (2005) explored the potentials of CORONA images for archaeological purposes and concluded that such images can be used as an alternative way in many European archaeological sites, where traditional aerial photography is very limited. Grosse et al., (2005) used CORONA images for mapping geomorphological features in NE Siberia. The combination of ASTER and CORONA images in northern Mesopotamia was al‐ so studied by Altaweel (2005).

tribute to the investigation of an archaeological site before, during and after excavation periods. At the micro-level scale, geophysical surveys and ground spectroscopy can pro‐ vide information about subsurface relics, while at the macro-scale, aerial photographs and satellite remote sensing can identify traces of the human past. Concurrently, these techniques can monitor the surroundings of a cultural heritage site and record any changes due urban expansion and/or changes of land use (Rowlands & Sarris, 2007; Ma‐ sini & Lasaponara, 2007; Hadjimitsis et al., 2009; Ventera et al., 2006; Negria & Leucci,

Satellite remote sensing has become a common tool of investigation, prediction and forecast of environmental change and scenarios through the development of GIS-based models and decision-support instruments that have further enhanced and considerably supported deci‐ sion-making (Ayad, 2005; Douglas, 2005; Hadjimitsis et al., 2006; Cavalli et al., 2007). By blending together satellite remote sensing techniques with GIS, the monitoring process of archaeological sites can be efficiently supported in a reliable, repetitive, non-invasive, rapid

This chapter presents a brief overview of the evolution of remote sensing in archaeologi‐ cal research. Several applications of applied remote sensing techniques, including satellite remote sensing, GIS, laser scanning, atmospheric pollution, spectroscopy, webGIS and ge‐ ophysical prospection will also be examined through different case studies in Cyprus and

This section introduces current remote sensing satellite data which are available for archaeo‐ logical research along with a historical background of remote sensing applications in archae‐ ology. As well, satellite sensors, such as Landsat, EO – Hyperion, QuickBird, IKONOS, etc.,

The first aerial photographs used for archaeological purposes were taken just before the be‐ ginning of World War I in UK and Italy (Capper, 1907; Parcak, 2009; Bewley et al., 1999; Riley, 1987). Mesopotamia and the Levant were traditionally photographed until the 1940s (see Keneddy, 1925; Crawford, 1923, Glueck, 1965, Keneddy, 2002). After the end of World War II, new archaeological sites were explored due to aerial reconnaissance during the war. The scientific interest has been currently shifted to the Middle and Far East, as well as other areas in Europe and America (Parcak, 2009). During the Cold War in the 1960's, several sat‐ ellites, including CORONA, Argo, Lanyard and COSMOS, were used for military purposes. However, these data were only accessible after their declassification in 1995 (Parcak, 2009).

Spatial resolution of CORONA spy images taken during the Cold War could reach up to 0.6m (Lock, 2003). Fowler & Fowler (2005) explored the potentials of CORONA images for

2006; Cavalli et al., 2007; Altaweel 2005; Aqdus et al., 2008; Bassani et al., 2009).

and cost-effective way (Hadjimitsis and Themistocleous, 2008).

58 Remote Sensing of Environment: Integrated Approaches

**2. Satellite remote sensing in archaeology**

Greece.

are also briefly outlined.

**2.1. Historical review**

KVR-100 images from the Russian space program have been available since 1987 and have a high spatial resolution of 2-3 m. Such data are valuable in areas where the landscape has changed dramatically as a result of human activity, such as urban expansion. Even though KVR-100 has been used by several researchers (Fowler and Curtis, 1995; Comfort, 1997), their application is still limited due to their high cost (Parcak, 2009). CORONA and KVR im‐ ages have been also used to monitor cultural heritage sites in Iran (Kostka, 2002).

Since the 1970s, the launch of new satellite systems coincided with the technological progress of the sensors. In 1972, the Landsat space program was initiated and was fol‐ lowed by the launch of other satellites, including the SPOT satellite in France (Parcak, 2009; Sarris, 2008). The Landsat sensor has been in continuous orbit since 1972 and pro‐ vides multispectral data for archaeological research. Despite the medium spatial resolu‐ tion (from 15-80m) Landsat images have a relatively low cost while covering a large area (180 x 180 km) in both the visible - infrared and thermal wavelengths. Landsat images were used to study archaeolandscapes in many archaeological projects and surveys. Vaughn and Crawford (2009) used predictive models in order to identify new areas with potential settlements of Mayans. Barlindhaug et al., (2007) found that Landsat satellite images can be used for monitoring purposes of archaeological sites. Neolithic settlements in Greece were detected using archive Landsat images (Alexakis, 2009; Agapiou et al., 2012a; 2012b). Landsat images were also used for monitoring purposes of the surround‐ ings of monuments in Cyprus (Hadjimitsis et al., 2009; 2008).

During the 1980's, thermal and radar sensors were also added to satellite sensors (Bewley et al., 1999). In the late 1980's, India launched the IRS 1A, 1B, 1C, 1D and IRS P2 sensors (Tripa‐ thi 2005a). Although these data have been used for archaeological purposes in India, such as the identification of the mythic site *Dvaraka* (Tripathi 2005b) and the observation of *Hampi* site (Raj et al., 2005), their use is very limited in other regions.

From the 1990's, remote sensing and Geographical Information Systems (GIS) have been used systematically for archaeological research and newer satellites with higher spatial reso‐ lution are now available. Indeed, Quickbird, IKONOS, WorldView and GeoEye are capable of providing satellite images with spatial resolution up to 0.5 m.

In addition to the above, hyperspectral images, such as those from EO-HYPERION, have re‐ cently made their appearance. Hyperspectral remote sensing analysis is performed over hundreds of narrow bands. The key characteristics of hyperspectral images are its fine spec‐ tral and radiometric resolution. Hyperspectral data provides a variety of spectral informa‐ tion, which can be used for the identification of archaeological remains. Alexakis et al., (2009) stated that these new technologies can support the detection of archaeological sites, although it is not always possible to extract a unique archaeological spectral signature due to the heterogeneous presence of vegetation and soil.

1960's. The Landsat program, which began in 1972 and continues to today, is considered a

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61

Prior to the Landsat program, satellite sensors such as CORONA and Zenit 2-8 sensors ac‐ quired only panchromatic photographs. These satellites were characterized by non-perio‐ dicity; therefore, some areas of archaeological interest may not have been photographed by these sensors. In contrast, the Landsat program has given further capabilities for research since the sensor is able to recover information in the visible, infrared and thermal part of the spectrum. Furthermore, the sun-synchronous orbit of the Landsat satellite enables research‐ ers to study many archaeological sites and monuments in a systematic way. From the begin‐ ning of the Landsat program until the end of the century, new multispectral satellite sensors were launched from different countries, including the USA, USSR, France, and Japan, and the spatial resolution of the images was significantly improved. In 1999, the first high-reso‐ lution satellite imagery with a spatial resolution of less than 4m was available through the IKONOS space program. The IKONOS satellite was the first satellite operated by a private organization (Space Imaging). In 2000, NASA launched the first hyperspectral receiver, the EO-1 Hyperion, which had the ability to record electromagnetic radiation into 220 different

In the decade that followed, new satellites with higher spatial resolution were available to the scientific community and other countries became actively involved in space technology. Brief descriptions of different satellite sensors characteristics are highlighted in Table 1 and more specific information related to the most popular satellite platforms used in archaeolog‐

**Landsat (MSS / TM / ETM +)**: The Landsat program was the result of the combined efforts of NASA and USGS to monitor Earth from space using remote sensing techniques. The first satellite launch was performed in 1972 (Landsat 1) and, since then, another 6 satellites were sent into orbit. According to Parcak (2009), the Landsat satellite program is the most well known satellite used for archaeological purposes due to its relative low cost, global coverage of the satellite data and access to archive data since the 1970's. Landsat satellite images cover an area of about 185 x 185 km. The multispectral bands of the sensor cover both the visible and infrared region of the spectrum while one sensor is able to produce thermal images. The panchromatic band of an ETM+ Landsat image has a spatial resolution of 15 m, while for the rest of the bands the resolution is set to 30 m with the exception of the thermal region (60 m). Landsat data can be obtained via FTP upon request from USGS (http://glovis.usgs.gov/).

**CHRIS Proba:** The Proba satellite belongs to a relatively new space program of the Europe‐ an Space Agency (ESA). The Compact High Resolution Imaging Spectrometer (CHRIS) sen‐ sor was launched on 2001 and provides hyperspectral images from 63 separate bands at a spatial resolution of 18 m. The objective of the CHRIS Proba is to evaluate new technologies for supporting future satellite sensors (experimental satellite) and to use the data for envi‐ ronmental purposes. The satellite data are acquired in HDF format after approval of ESA

committee. A single satellite image covers an area of 13 x 13 km.

significant component of remote sensing applications in archaeology.

spectral bands.

ical research are provided in the paragraphs below.

Lasaponara and Masini (2007a) highlighted the potential benefits of high resolution satellite images in order to detect subsurface monuments through the use of vegetation indices and edge detection techniques. Cavalli et al., (2007) introduced the use of airborne hyperspectral scanner Multispectral Infrared Visible Imaging Spectrometer ( MIVIS) for the detection of subsurface monuments based on spectral anomalies. The study found that the detection of subsurface monuments is possible employing both visible and near infrared part of electro‐ magnetic radiation, and can concurrently detect anomalies using the thermal infrared spec‐ trum. Using QuickBird satellite imagery, Lasaponara and Masini (2007b) examined the Metaponto archaeological sites in the South of Italy, using sophisticated spectral techniques such as the Tasselled Cap Transformation and Principal Component Analysis. The combina‐ tion of hyperspectral data and several remote sensing processing techniques (Principal Component Analysis, vegetation indices, etc.) for the detection of subsurface monuments in eastern Scotland was also presented by Aqdus et al., (2009).

Beck (2007) and Beck et al., (2007) conducted a detail study of the archaeological site of *Homs* in Syria, using CORONA and IKONOS images. The results indicated that areas with archaeological interest tend to have different spectral signatures from the surround‐ ing area. Rowlands and Sarris (2007) used airborne hyperspectral scanners (Airborne Thematic Mapper –ATM and Compact Airborne Spectrographic Imager -CASI) and LI‐ DAR data in order to study the Hellenistic settlement of *Itanos* in Crete. The data were post-processed using object-oriented analysis. Although the study found several difficul‐ ties in relation to the identification of archaeological remains, the continuing use of such methods and applications along with other remote sensing techniques such as geophysi‐ cal surveys was recommended. In the ancient city *Sagalassos*, Laet et al., (2007) applied object-oriented techniques and several satellite images (ASTER, SPOT, IKONOS) in order to identify archaeological remains. The results from investigations , in the Piramide Nar‐ anjada in Cahuachi (Peru), based on high resolution satellite imagery, geomagnetic sur‐ veys and Ground Probing Radar was recently presented by Lasaponara et al., (2011). Currently, several archaeological investigations are carried out using combined remote sensing techniques, such as satellite images, aerial photographs, ground geophysical sur‐ veys, and LIDAR measurements. The next section provides an outline of the characteris‐ tics of the most important satellite data available today for archaeological research.

#### **2.2. Satellite image data**

Currently, there is a plethora of satellite images which may be used for supporting archaeo‐ logical research. However, these images have different resolutions depending on the sensor characteristics. Moreover, many of these satellite systems are nowadays inactive, but their data can be still be used for research. Table 1 summarizes some of the general characteristics of several satellite data regarding spatial, spectral and temporal resolution. As indicated in Table 1, as a result of the space race, satellites have been able to monitor Earth since the 1960's. The Landsat program, which began in 1972 and continues to today, is considered a significant component of remote sensing applications in archaeology.

although it is not always possible to extract a unique archaeological spectral signature due

Lasaponara and Masini (2007a) highlighted the potential benefits of high resolution satellite images in order to detect subsurface monuments through the use of vegetation indices and edge detection techniques. Cavalli et al., (2007) introduced the use of airborne hyperspectral scanner Multispectral Infrared Visible Imaging Spectrometer ( MIVIS) for the detection of subsurface monuments based on spectral anomalies. The study found that the detection of subsurface monuments is possible employing both visible and near infrared part of electro‐ magnetic radiation, and can concurrently detect anomalies using the thermal infrared spec‐ trum. Using QuickBird satellite imagery, Lasaponara and Masini (2007b) examined the Metaponto archaeological sites in the South of Italy, using sophisticated spectral techniques such as the Tasselled Cap Transformation and Principal Component Analysis. The combina‐ tion of hyperspectral data and several remote sensing processing techniques (Principal Component Analysis, vegetation indices, etc.) for the detection of subsurface monuments in

Beck (2007) and Beck et al., (2007) conducted a detail study of the archaeological site of *Homs* in Syria, using CORONA and IKONOS images. The results indicated that areas with archaeological interest tend to have different spectral signatures from the surround‐ ing area. Rowlands and Sarris (2007) used airborne hyperspectral scanners (Airborne Thematic Mapper –ATM and Compact Airborne Spectrographic Imager -CASI) and LI‐ DAR data in order to study the Hellenistic settlement of *Itanos* in Crete. The data were post-processed using object-oriented analysis. Although the study found several difficul‐ ties in relation to the identification of archaeological remains, the continuing use of such methods and applications along with other remote sensing techniques such as geophysi‐ cal surveys was recommended. In the ancient city *Sagalassos*, Laet et al., (2007) applied object-oriented techniques and several satellite images (ASTER, SPOT, IKONOS) in order to identify archaeological remains. The results from investigations , in the Piramide Nar‐ anjada in Cahuachi (Peru), based on high resolution satellite imagery, geomagnetic sur‐ veys and Ground Probing Radar was recently presented by Lasaponara et al., (2011). Currently, several archaeological investigations are carried out using combined remote sensing techniques, such as satellite images, aerial photographs, ground geophysical sur‐ veys, and LIDAR measurements. The next section provides an outline of the characteris‐ tics of the most important satellite data available today for archaeological research.

Currently, there is a plethora of satellite images which may be used for supporting archaeo‐ logical research. However, these images have different resolutions depending on the sensor characteristics. Moreover, many of these satellite systems are nowadays inactive, but their data can be still be used for research. Table 1 summarizes some of the general characteristics of several satellite data regarding spatial, spectral and temporal resolution. As indicated in Table 1, as a result of the space race, satellites have been able to monitor Earth since the

to the heterogeneous presence of vegetation and soil.

60 Remote Sensing of Environment: Integrated Approaches

eastern Scotland was also presented by Aqdus et al., (2009).

**2.2. Satellite image data**

Prior to the Landsat program, satellite sensors such as CORONA and Zenit 2-8 sensors ac‐ quired only panchromatic photographs. These satellites were characterized by non-perio‐ dicity; therefore, some areas of archaeological interest may not have been photographed by these sensors. In contrast, the Landsat program has given further capabilities for research since the sensor is able to recover information in the visible, infrared and thermal part of the spectrum. Furthermore, the sun-synchronous orbit of the Landsat satellite enables research‐ ers to study many archaeological sites and monuments in a systematic way. From the begin‐ ning of the Landsat program until the end of the century, new multispectral satellite sensors were launched from different countries, including the USA, USSR, France, and Japan, and the spatial resolution of the images was significantly improved. In 1999, the first high-reso‐ lution satellite imagery with a spatial resolution of less than 4m was available through the IKONOS space program. The IKONOS satellite was the first satellite operated by a private organization (Space Imaging). In 2000, NASA launched the first hyperspectral receiver, the EO-1 Hyperion, which had the ability to record electromagnetic radiation into 220 different spectral bands.

In the decade that followed, new satellites with higher spatial resolution were available to the scientific community and other countries became actively involved in space technology. Brief descriptions of different satellite sensors characteristics are highlighted in Table 1 and more specific information related to the most popular satellite platforms used in archaeolog‐ ical research are provided in the paragraphs below.

**Landsat (MSS / TM / ETM +)**: The Landsat program was the result of the combined efforts of NASA and USGS to monitor Earth from space using remote sensing techniques. The first satellite launch was performed in 1972 (Landsat 1) and, since then, another 6 satellites were sent into orbit. According to Parcak (2009), the Landsat satellite program is the most well known satellite used for archaeological purposes due to its relative low cost, global coverage of the satellite data and access to archive data since the 1970's. Landsat satellite images cover an area of about 185 x 185 km. The multispectral bands of the sensor cover both the visible and infrared region of the spectrum while one sensor is able to produce thermal images. The panchromatic band of an ETM+ Landsat image has a spatial resolution of 15 m, while for the rest of the bands the resolution is set to 30 m with the exception of the thermal region (60 m). Landsat data can be obtained via FTP upon request from USGS (http://glovis.usgs.gov/).

**CHRIS Proba:** The Proba satellite belongs to a relatively new space program of the Europe‐ an Space Agency (ESA). The Compact High Resolution Imaging Spectrometer (CHRIS) sen‐ sor was launched on 2001 and provides hyperspectral images from 63 separate bands at a spatial resolution of 18 m. The objective of the CHRIS Proba is to evaluate new technologies for supporting future satellite sensors (experimental satellite) and to use the data for envi‐ ronmental purposes. The satellite data are acquired in HDF format after approval of ESA committee. A single satellite image covers an area of 13 x 13 km.


**EO-1 HYPERION**: HYPERION was the first satellite of a new generation space program which was launched by NASA in 2000. The satellite's main objective was to collect experi‐ mental data for future receivers. The main feature of the HYEPRION satellite was the ac‐ quisition of hyperspectral data (a total of 220 separate bands) at a spectral range from 356 nm to 2577 nm. The spatial resolution of the data was 30 m. HYPERION data can be ob‐

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**IKONOS**: IKONOS is a commercial satellite with high spatial resolution. It was sent into or‐ bit in 1999 and can provide images with spatial resolution up to 1m for panchromatic im‐ ages and 4m in multispectral bands. The spectral resolution of the sensor extends from the visible to near infrared. Although IKONOS images are widely available to the research com‐ munity, they are not recorded on a regular basis. The radiometric resolution of the satellite is 11 bit and a single image can cover an area of about 13 x 13 km. IKONOS satellite can provide stereo images in order to support the production of Digital Terrain Models and Sur‐ face Terrain Models (DEM, DSM). IKONOS data are available from GeoEye upon request

**QuickBird**: Quickbird is owned by the commercial satellite company DigitalGlobe and was sent into sun-synchronous orbit in 2001. The satellite is currently one of the few satellites with the highest spatial resolution (e.g. OrbView-2, OrbView-3, WorldView-1, WorldView-2 and GeoEye-1). The spatial resolution is up to 0.60 m in the panchromatic wavelength while multispectral bands are acquired at a resolution of 2.4 m. The spectral capacity is equivalent to the IKONOS satellite (visible and near infrared). Moreover, QuickBird images cover a ground area of 16.5 x 16.5 km. QuickBird data is available from DigitalGlobe after request

**WorldView:** WorldView satellite were launched in 2007 (WorldView -1) while a second sen‐ sor followed a few years later (WorldView-2). These sensors have a very high spatial resolu‐ tion (0.5m). The WorldView-2 sensor provides a high resolution panchromatic band and eight Multispectral bands; four standard colors (red, green, blue, and near-infrared) and four new bands (coastal, yellow, red edge, and near-infrared). WorldView data is available

**GeoEye-1**: GeoEye is the latest high spatial resolution satellite that was sent into space (2008). The spatial resolution of the satellite is 0.41 m and 1.65 m (panchromatic / multispec‐ tral bands). The spectral resolution is limited to visible and near infrared wavelength. A Ge‐

**CORONA:** From 1960 until 1972, the CORONA satellite acquired over 860,000 panchro‐ matic images for US Intelligence. The photographic capsule from the spy satellite was dropped to earth with the help of parachute and then was collected by a special aircraft (Figure 1). The CORONA images were declassified in 1995, and are now available in digi‐

Remote sensing has been able to assist archaeological research in several ways during the past years, including detection of subsurface remains, monitoring archaeological sites and monuments, archaeolandscapes studies, etc. The next section presents recent developments

tained via FTP upon request from USGS (http://glovis.usgs.gov/).

from DigitalGlobe upon request (http://www.digitalglobe.com).

(http://www.satimagingcorp.com/).

(http://www.digitalglobe.com).

oEye-1 image covers an area of 15 x 15 km.

tal form upon request.

**Table 1.** List of available satellite sensors for archaeological purposes.

**EO-1 HYPERION**: HYPERION was the first satellite of a new generation space program which was launched by NASA in 2000. The satellite's main objective was to collect experi‐ mental data for future receivers. The main feature of the HYEPRION satellite was the ac‐ quisition of hyperspectral data (a total of 220 separate bands) at a spectral range from 356 nm to 2577 nm. The spatial resolution of the data was 30 m. HYPERION data can be ob‐ tained via FTP upon request from USGS (http://glovis.usgs.gov/).

**Satellite Sensor Acquisition period**

62 Remote Sensing of Environment: Integrated Approaches

Cartosat-1 (IRS-P5)

IRS

**Spatial resolutions Spectral Resolution**

**Pan VIS-NIR**

2005-Today 2.5 Panchromatic under req.

ALOS PRISM 2006-Today 2.5 10 420 -890 46 days CBERS HRCC 2003-Today 20 450 - 890 26 days

CARTOSAT-1 2005-Today 2.5 Panchromatic 116 days EO-1 ALI 2000- Today 10 30 433-890 under req. EO-1 Hyperion 2000-Today 10 356-996 under req. FORMOSAT-2 2004-Today 2 8 450 -900 under req. GeoEye-1 2008-Today 0.41 1.65 450 -920 under req. IKONOS 1999-Today 1 4 450 -950 under req.

IRS Cartosat-2B 2010-Today 1 Panchromatic under req. IRS Resourcesat-1 (IRS-P6) 2003-Today 5.8 23.5 520 -860 under req. IRS Resourcesat-2 2011-Today 5.8 23.5 520 -860 under req. IRS 1C / 1D 1996/7-Today 5.8 23.5 520 -860 under req. KOMPSAT-2 2006-Today 1 4 450 -900 under req.

Landsat 5 TM 1984-Today 15 30 450 -900 16 days Landsat 7 ETM+ 1999-Today 15 30 450 -900 16 days Orbview-3 2003-Today 1 4 450 -900 under req. Pleiades-1 2011-Today 0.5 2 430-950 under req. Proba CHIRS 2001-Today 17-34 415-1050 under req. QuickBird - 2001-Today 0,60 2,4 450 -900 under req. RapidEye 2008-Today 5 440 - 850 under req.

SPOT-4 HRVIR 1998-Today 10 20 500-890 under req. SPOT-5 HRG 2002-Today 5 10 500-890 under req. Terra ASTER 1999-Today 15 520-860 under req.

WorldView-1 2007-Today 0.5 Panchromatic under req. WorldView-2 2009-Today 0.5 1.8 400-1040 under req.

CORONA 1960-1972 1.8 – 12 Panchromatic

Kometa KVR-1000 1981-2005 2-3 Panchromatic Kometa TK-350 1981-2005 2-3 Panchromatic Landsat 4 MSS 1982-1993 60 520 - 900

SPOT-1 HRV 1986-2003 10 20 500-890 SPOT-2 HRV 1990-2009 10 20 500-890 SPOT-3 HRV 1993-1996 10 20 500-890

Kometa KVR-1000 1981-2005 2-3 Panchromatic TK-350 2-3 Panchromatic

Zenit 2-8 1961-1994 15-2 Panchromatic

**Table 1.** List of available satellite sensors for archaeological purposes.

**(nm) (only VIS-VNIR are listed)** **Temporal Resolution**

**IKONOS**: IKONOS is a commercial satellite with high spatial resolution. It was sent into or‐ bit in 1999 and can provide images with spatial resolution up to 1m for panchromatic im‐ ages and 4m in multispectral bands. The spectral resolution of the sensor extends from the visible to near infrared. Although IKONOS images are widely available to the research com‐ munity, they are not recorded on a regular basis. The radiometric resolution of the satellite is 11 bit and a single image can cover an area of about 13 x 13 km. IKONOS satellite can provide stereo images in order to support the production of Digital Terrain Models and Sur‐ face Terrain Models (DEM, DSM). IKONOS data are available from GeoEye upon request (http://www.satimagingcorp.com/).

**QuickBird**: Quickbird is owned by the commercial satellite company DigitalGlobe and was sent into sun-synchronous orbit in 2001. The satellite is currently one of the few satellites with the highest spatial resolution (e.g. OrbView-2, OrbView-3, WorldView-1, WorldView-2 and GeoEye-1). The spatial resolution is up to 0.60 m in the panchromatic wavelength while multispectral bands are acquired at a resolution of 2.4 m. The spectral capacity is equivalent to the IKONOS satellite (visible and near infrared). Moreover, QuickBird images cover a ground area of 16.5 x 16.5 km. QuickBird data is available from DigitalGlobe after request (http://www.digitalglobe.com).

**WorldView:** WorldView satellite were launched in 2007 (WorldView -1) while a second sen‐ sor followed a few years later (WorldView-2). These sensors have a very high spatial resolu‐ tion (0.5m). The WorldView-2 sensor provides a high resolution panchromatic band and eight Multispectral bands; four standard colors (red, green, blue, and near-infrared) and four new bands (coastal, yellow, red edge, and near-infrared). WorldView data is available from DigitalGlobe upon request (http://www.digitalglobe.com).

**GeoEye-1**: GeoEye is the latest high spatial resolution satellite that was sent into space (2008). The spatial resolution of the satellite is 0.41 m and 1.65 m (panchromatic / multispec‐ tral bands). The spectral resolution is limited to visible and near infrared wavelength. A Ge‐ oEye-1 image covers an area of 15 x 15 km.

**CORONA:** From 1960 until 1972, the CORONA satellite acquired over 860,000 panchro‐ matic images for US Intelligence. The photographic capsule from the spy satellite was dropped to earth with the help of parachute and then was collected by a special aircraft (Figure 1). The CORONA images were declassified in 1995, and are now available in digi‐ tal form upon request.

Remote sensing has been able to assist archaeological research in several ways during the past years, including detection of subsurface remains, monitoring archaeological sites and monuments, archaeolandscapes studies, etc. The next section presents recent developments and applications of several remote sensing techniques for supporting archaeological re‐ search. The section includes detection of subsurface remains at the Thessalian plain based on both satellite and ground spectroradiometric measurements. Moreover, remote sensing and GIS analysis as means for monitoring purposes in the area of Cyprus are also examined. Geophysical surveys from various archaeological sites are also presented as well as the re‐ sults of a study aiming to analyse the impact of atmospheric pollution on archaeological sites. The section ends with discussion of low-altitude airborne systems, as well as 3D laser scanner documentation of cultural heritage site.

cant problem of extensive urbanization in the vicinity of cultural heritage sites. Almost 50% of the CH sites are under severe urban pressure and a percentage of 37.5% of the sites are within a radius of 500m from the urban centers. In similar studies, Carlon et al., (2002) and (Alexakis and Sarris, 2010) used both anthropogenic and natural factors to cre‐ ate a risk assessment model concerning archaeological monuments in Venice and West‐ ern Crete respectively. Moreover, Urhus et al (2006) emphasized the human driven agents, such as camping, hunting and woodcutting, for assessing the modern threats to heritage resources and Lanza (2003) addressed the potential threat that is posed at the

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65

This section presents the contribution of remote sensing for monitoring the surroundings of archaeological sites in order the managing authorities or governmental related bodies to be able to conduct a risk assessment analysis of cultural heritage sites in Cyprus. Figure 2 presents some of the most indicative threat parameters. Special attention in this section is given to urban expansion during the past 50 years. Anthropogenic factors, such as urban ex‐ pansion and air pollution contribute significantly to the destruction of cultural heritage sites. Remote sensing and GIS provide synoptic views of cultural heritage sites which enable poli‐ cy makers to make appropriate decisions regarding the preservation of cultural heritage

historical center of Genoa in the case of failure of the urban drainage system.

**Figure 2.** Risk assessment analysis for cultural heritage sites (Hadjimitsis et al., 2011)

**3.1. Urban expansion and other hazards as a threat to archaeological sites**

In order to study and map urban expansion, a number of significant archaeological sites of Cyprus were examined. These cultural heritage sites are located in the southern coast‐

sites.

**Figure 1.** Film capsule of the CORONA satellite collected from aircrafts. (Photos from Wikipedia and CSNR collection)
