A Hand-drawn Map Retrieval Method Based on Open Area Spatial Direction Relation
AN Xiaoya, LIU Pingzhi, JIN Cheng, XU Daozhu, WANG Feng
Acta Geodaetica et Cartographica Sinica . 2017, (11): 1899 -1909 .  DOI: 10.11947/j.AGCS.2017.20170001