On the use of historical archive of aerial photographs for the discovery and interpretation of ancient hidden linear cultural relics in the alluvial plain of eastern Henan, China

Hidden linear ancient cultural relics were discovered in the alluvial plain of Eastern Henan province (China) using historical archive of aerial photographs and further confirmed by regional features, historical documents and recent archaeological progress. The discovered relics included large-scale man-made ditches, canals and dock relics in Shangqiu and circular moat relics in Luyi. According to historical documents and archaeological researches, we discussed the cultural types and natures of the relics discovered by remote sensing images. On this basis, more pertinent and operable interpretation marks were proposed focusing on hidden linear ancient cultural relics in the alluvial plain. To improve the interpretation of the traditional crop, soil and shadow marks, we also included indexes of scale, continuity, shape and clustering. Our research highlights the macroscopic and spectrographic observation capability of remote sensing in discovering large-scale, massive, surface distribution of ancient cultural relics. In the test area, the solution of image interpretation was proposed through a combined feature identification of scale, continuity, shape and clustering. The derived thematic map demonstrated that the proposed solution is effective for discovering ancient remains in the alluvial plain of eastern Henan, China.