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Remote Sens. 2014, 6(12), 11956-11976;

Automated Extraction of the Archaeological Tops of Qanat Shafts from VHR Imagery in Google Earth

1,3,* , 1,3
Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China
University of the Chinese Academy of Sciences, Beijing 100049, China
International Centre on Space Technologies for Natural and Cultural Heritage under the Auspices of UNESCO, Beijing 100094, China
Gansu Provincial Institute of Urban Development, Lanzhou 730070, China
These authors contributed equally to this work.
Author to whom correspondence should be addressed.
Received: 27 August 2014 / Revised: 26 October 2014 / Accepted: 12 November 2014 / Published: 1 December 2014
(This article belongs to the Special Issue New Perspectives of Remote Sensing for Archaeology)
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Qanats in northern Xinjiang of China provide valuable information for agriculturists and anthropologists who seek fundamental understanding of the distribution of qanat water supply systems with regard to water resource utilization, the development of oasis agriculture, and eventually climate change. Only the tops of qanat shafts (TQSs), indicating the course of the qanats, can be observed from space, and their circular archaeological traces can also be seen in very high resolution imagery in Google Earth. The small size of the TQSs, vast search regions, and degraded features make manually extracting them from remote sensing images difficult and costly. This paper proposes an automated TQS extraction method that adopts mathematical morphological processing methods before an edge detecting module is used in the circular Hough transform approach. The accuracy assessment criteria for the proposed method include: (i) extraction percentage (E) = 95.9%, branch factor (B) = 0 and quality percentage (Q) = 95.9% in Site 1; and (ii) extraction percentage (E) = 83.4%, branch factor (B) = 0.058 and quality percentage (Q) = 79.5% in Site 2. Compared with the standard circular Hough transform, the quality percentages (Q) of our proposed method were improved to 95.9% and 79.5% from 86.3% and 65.8% in test sites 1 and 2, respectively. The results demonstrate that wide-area discovery and mapping can be performed much more effectively based on our proposed method. View Full-Text
Keywords: qanats; extraction; archaeological traces; circular Hough transform; Google Earth; very high resolution qanats; extraction; archaeological traces; circular Hough transform; Google Earth; very high resolution

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Luo, L.; Wang, X.; Guo, H.; Liu, C.; Liu, J.; Li, L.; Du, X.; Qian, G. Automated Extraction of the Archaeological Tops of Qanat Shafts from VHR Imagery in Google Earth. Remote Sens. 2014, 6, 11956-11976.

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