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Luo L.,CAS Institute of Remote Sensing | Luo L.,University of Chinese Academy of Sciences | Luo L.,International Center on Space Technologies for Natural | Wang X.,CAS Institute of Remote Sensing | And 13 more authors.
Remote Sensing | Year: 2014

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. © 2014 by the authors.

Luo L.,International Center on Space Technologies for Natural | Luo L.,CAS Institute of Remote Sensing | Wang X.Y.,International Center on Space Technologies for Natural | Wang X.Y.,CAS Institute of Remote Sensing | And 4 more authors.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2015

The aim of this study was to give a comprehensive archaeological investigation for Penghu's stone tidal weirs (STWs) based on both Google Earth and GIS. Firstly, this study uses GoogleEarth Pro tools to clip a GeoEye-1 image (acquisition date: 22/07/2013) and a WorldView-2 image (acquisition date: 25/01/2014) for Chipei Island and Husi Island, respectively, and save them at a "premium resolution" of 4800 dpi. More, using 15 m panchromatic orthorectified Landsat images as a base, two clips were geo-referenced in ENVI 5.1 with minimal root mean square error. Furthermore, the STWs were manual extracted from the two GoogleEarth images in ArcGIS 10.1. Category and size statistics are presented; construction structure and weir function are discussed. Lastly, by using GIS analyses, STWs characteristics of intertidal flats across Penghu archipelago have been mapped and related to key geographical environmental variables. From spring to summer of 2015 our research team conducted investigations into Penghu's STWs based on different seasons and time periods of GoogleEarth historic images. Our results showed that, distributed amongst Penghu's coastline, there are 503 STWs. Compared with the official survey results (around 592 STWs), the counts are similar but the GoogleEarth-based method is more time-saving and efficient.

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