The use of high resolution digital surface models for change detection and viewshed analysis in the area around the pyramids of Giza, Egypt

One of the biggest threats to cultural heritage is related to their rapidly changing and developing surroundings. The Giza pyramid plateau is a prime example of this phenomenon, as it is threatened by the enormous urban expansion of Cairo over the last decades. Documenting, monitoring and modelling such a pressure requires accurate and detailed geographic data, which can be derived from recent up-to-date, high resolution satellite images. Remote sensing techniques have proven to be very useful to visualize and analyze urban sprawl and land use changes in two dimensions. The impact assessment of urban sprawl near specific heritage sites, however; needs to be complemented with accurate 2.5D-information. In an attempt to do so, digital surface models (DSMs) from Ikonos-2 (2005) and GeoEye-1 stereoscopic images (2009 and 2011) have been computed in order to analyze recent urban changes. Change detection methods are mainly developed for large scale high resolution aerial images; however this paper focuses on the one hand DSM creation and its challenges resulting in an improvement of 2.5D change detection method for small scale satellite imagery in mainly informal areas. On the other hand a view shed evolution is presented. The combination of the enhanced digital terrain extraction (eATE) module of Erdas Imagine® and ground control points collected in the field provides accurate and high resolution DSMs. The impact of shadow and different urban morphologies however influence the pixel-wise comparison of the two DSMs, which results in different approaches for different city districts. The resulting 2.5D change model clarifies not only the urban sprawl, but also the increase in building levels, directly related to pressure on the famous pyramids. This pressure is furthermore analyzed by creating different view sheds through time from the plateau towards the city and vice versa. An integration of population statistics complements the model, hence allowing it to become a useful policy instrument

Overview of the SBS 2016 Mining Track

Abstract. In this paper we present an overview of the mining track in the Social Book Search (SBS) lab 2016. The mining track addressed two tasks: (1) classifying forum posts as book search requests, and (2) linking book title mentions in forum posts to unique book IDs in a database. Both tasks are important steps in the process of solving complex search tasks within online reader communities. We prepared two data collections for the classification task: posts from the LibraryThing (LT) forum and a smaller number of posts from Reddit. For the linking task we used annotated LT threads. We found that the classification task was relatively straightforward, achieving up to 94% classification accuracy. The book linking task on the other hand turned out to be a difficult task: here the best system achieved an accuracy of 41% and F-score of 33.5%. Both the automatic classification of book search requests as the automatic linking of book mentions could next year be part of the pipeline for processing complex book searches

Using surface models to analyze and detect urban pressure around the Pyramids of Giza, Egypt

One of the largest threats to cultural heritage is their rapidly changing surroundings. The Giza pyramid plateau (Egypt) is a prime example of this phenomenon, asitis threatened by the enormous urban expansion of Cairo over the last decades. Geographic data derived from satellite images is very important for documenting and detecting suchan expansion especially urbanareas without accurate cadaster and population statistics like Cairo. Remote sensing techniques have proven to be very useful to visualize and analyze urban sprawl and land use changes in two dimensions. However, the impact assessment of urban sprawl needs to be complemented with accurate elevation data, because this urban sprawl is not only limited to planimetric growth. To create this accurate elevation data, digital surface models (DSMs) from Corona (1970), Ikonos (2005) and GeoEye (2009 and 2011) images have been computed using photogrammetric software and ground control points. This work focuses first of all on a procedure to improve 2.5D change detection from satellite imagery in mainly informal areas. A pixel-wise subtraction is performed on the 2009 and 2011 DSMs resulting in an automated change detection workflow. The proposed workflow is validated in the Hada‘iq al-Ahram or Pyramid Gardens stretching west of the Giza Pyramid plateau. Based on statistical analyses of these change maps, it can be concluded that the proposed 2.5D change detection workflow using raster DSMs is the closest to reality. The resulting change maps for western Cairo do not only clarify the horizontal urban sprawl, but also the increase in building levels increase, i.e. the vertical urban expansion. Since horizon pollution is a major factor in heritage protection, a second focus is on the evolution of the view towards and from the famous pyramids during the last four decades. A viewshed analysis is performed on all DSMs resulting in change maps indicating the evolution throughout the past 40 years. With this work we proved that surface model s are very useful for analyzing urban pressure on cultural heritage sites and we hope that this work will be used in the protection and conservation of our world heritage. This abstract fit within the APLADYN project: a Belgian Science Policy project on anthropogenic and landscape dynamics in large fluvial systems

Landscape evolution in the Nile Valley: physical and anthropogenic 3D changes in the last 40 years in Dayr al-Barsha

The last four decades, worldwide, the landscape rapidly evolved in both a physical and anthropogenic sense. Here, the Nile valley is used as a prime example of how human impact may influence the physical environment. Due to its rich heritage, the cultural and environmental history of the Nile valley has already tremendously been studied. Studies focusing on the cultural history of the Nile valley are mostly field based and pinpointed towards specific target sites. These sites however were implanted in the regional landscape, and as such, information on these sites and their regional landscape are of equal importance. Digital surface models (DSMs), extracted from very high resolution stereoscopic satellite images, are a perfect tool to gain knowledge on this regional landscape aspect. In this study Corona images from 1970 and a Worldview-1 images (WV-1) from 2009 have been used in order to reveal not only environmental changes over the last four decades. In addition it also gets information on the natural landscape before the construction of the Aswan Dam, which was finished in 1970 blocking the famous natural Nile floods and major human impact could began. In this paper the challenges of DSM extraction from Corona and WV-1 images is discussed together with the detection of palaeo river channels and the evolution of anthropogenic features like villages all in the surroundings of Dayr-al Barsha (Middle-Egypt). The combination of the enhanced digital terrain extraction (eATE) module of Erdas Imagine and ground control points collected in the field provides accurate and high resolution DSMs. These surface models revealed potential palaeo river channels, and their presence has been confirmed by targeted geomorphological fieldwork in the region. Comparison between the Corona and the WV-1 DSM revealed that human impact on the landscape has been significant over the last four decades. All villages are grown in size and height. Even a number of new villages have been constructed over the last forty years. In the near future these models will be integrated with geomorphological an archaeological data in order to better understand the environmental as well as cultural evolution of the landscape in the region under study

The use of high resolution digital surface models for change detection and viewshed analysis in the urban area around the pyramids of Giza, Egypt

One of the biggest threats to cultural heritage is related to their rapidly changing and developing surroundings. The Giza pyramid plateau is a prime example of this phenomenon, as it is threatened by the enormous urban expansion of Cairo over the last decades. Documenting, monitoring and modelling such a pressure requires accurate and detailed geographic data, which can be derived from recent up-to-date, high resolution satellite images. Remote sensing techniques have proven to be very useful to visualize and analyze urban sprawl and land use changes in two dimensions. The impact assessment of urban sprawl near specific heritage sites, however; needs to be complemented with accurate 2.5D-information. In an attempt to do so, digital surface models (DSMs) from Ikonos-2 (2005) and GeoEye-1 stereoscopic images (2009 and 2011) have been computed in order to analyze recent urban changes. Change detection methods are mainly developed for large scale high resolution aerial images; however this paper focuses on the one hand DSM creation and its challenges resulting in an improvement of 2.5D change detection method for small scale satellite imagery in mainly informal areas. On the other hand a view shed evolution is presented. The combination of the enhanced digital terrain extraction (eATE) module of Erdas Imagine® and ground control points collected in the field provides accurate and high resolution DSMs. The impact of shadow and different urban morphologies however influence the pixel-wise comparison of the two DSMs, which results in different approaches for different city districts. The resulting 2.5D change model clarifies not only the urban sprawl, but also the increase in building levels, directly related to pressure on the famous pyramids. This pressure is furthermore analyzed by creating different view sheds through time from the plateau towards the city and vice versa. An integration of population statistics complements the model, hence allowing it to become a useful policy instrument