Auto-Extraction of Linear Archaeological Traces of Tuntian Irrigation Canals in Miran Site (China) from Gaofen-1 Satellite Imagery

Abstract

This paper describes the use of the Chinese Gaofen-1 (GF-1) satellite imagery to automatically extract tertiary Linear Archaeological Traces of Tuntian Irrigation Canals (LATTICs) located in the Miran site. The site is adjacent to the ancient Loulan Kingdom at the eastern margin of the Taklimakan Desert in western China. GF-1 data were processed following atmospheric and geometric correction, and spectral analyses were carried out for multispectral data. The low values produced by spectral separability index (SSI) indicate that it is difficult to distinguish buried tertiary LATTICs from similar backgrounds using spectral signatures. Thus, based on the textual characteristics of high-resolution GF-1 panchromatic data, this paper proposes an automatic approach that combines joint morphological bottom and hat transformation with a Canny edge operator. The operator was improved by adding stages of geometric filtering and gradient vector direction analysis. Finally, the detected edges of tertiary LATTICs were extracted using the GIS-based draw tool and converted into shapefiles for archaeological mapping within a GIS environment. The proposed automatic approach was verified with an average accuracy of 95.76% for 754 tertiary LATTICs in the entire Miran site and compared with previous manual interpretation results. The results indicate that GF-1 VHR PAN imagery can successfully uncover the ancient tuntian agricultural landscape. Moreover, the proposed method can be generalized and applied to extract linear archaeological traces such as soil and crop marks in other geographic locations.

Identifying Linear Traces of the Han Dynasty Great Wall in Dunhuang Using Gaofen-1 Satellite Remote Sensing Imagery and the Hough Transform

“…where µ 1(λ) and µ 2(λ) are the means of two different classes (such as linear traces and their surroundings), and σ 1(λ) and σ 2(λ) represent the corresponding standard deviations. A greater M value means a higher separability between the two classes since the intra-class variance is minimized and the inter-class variance is maximized [61]. Based on our previous study [61], M < 1.0 and M > 1.0 represent poor and good class separation, respectively.…”

“…For RS specialists and archaeologists, obtaining spatial information about AOIs from various sources of data is the original and primary goal of archaeological remote sensing research [59]. In general, AOIs can be detected in RS imagery as grid data or vector data using visual or automatic interpretation following image enhancement and data fusion [61]. However, there are some long-standing problems pointed out by Luo et al [47], such as low level of automation and extremely limited range of spatial scales and spectral contrasts in AOIs' identification.…”

“…The Dunhuang Section of the GH was an important part of the overall GH defense system in the Hexi Corridor, as well as being symbolic of the defense system in northwest China during the Han Dynasty. interpretation following image enhancement and data fusion [61]. However, there are some longstanding problems pointed out by Luo et al [47], such as low level of automation and extremely limited range of spatial scales and spectral contrasts in AOIs' identification.…”

“…The Dunhuang Section of the GH was an important part of the overall GH defense system in the Hexi Corridor, as well as being symbolic of the defense system in northwest China during the Han Dynasty. The strategic position of ancient Dunhuang and the convenient communication that it enjoyed favored continuous anthropogenic activity [19,61] from pre-historic times to the imperial period, The strategic position of ancient Dunhuang and the convenient communication that it enjoyed favored continuous anthropogenic activity [19,61] from pre-historic times to the imperial period, especially during the Han-Tang period, as has been confirmed by various excavated archaeological materials, monuments, historical remains and ancient documents [9,10,[14][15][16]. The Dunhuang Section of the GH, distributed about 80 km north of the modern oasis city of Dunhuang, is now one of the most significant pieces of large-scale linear cultural heritage, and the best-preserved section of the GH in China [4].…”

“…All of the data pre-processing was carried out in ENVI5.4 [63]. Additionally, the 10 corrected PAN images used in this paper were also enhanced using the joint morphological transformation approach that was proposed in our previous study [61].…”