Bulletin of Surveying and Mapping ›› 2023, Vol. 0 ›› Issue (4): 93-98.doi: 10.13474/j.cnki.11-2246.2023.0110

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Matching pair retrieval method of UAV images based on the graph structure bag of words model

LIU Sikang1, GUO Bingxuan1, JIANG San2, YAN Maosheng1   

  1. 1. State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China;
    2. School of Computer Science, China University of Geosciences, Wuhan 430074, China
  • Received:2022-05-11 Published:2023-04-25

Abstract: Matching pair selection is a key technology to improve feature matching efficiency and 3D reconstruction reliability of UAV images. However, the classical tree index structure word bag model has low efficiency in finding words, low precision in similarity calculation, and high time cost in image retrieval. This study designs the navigation small world (NSW) graph index structure and TF-IDF-Match4 algorithm, and proposes matching pair retrieval method based on the Graph Structure Bag of Words (GSBoW) model. Firstly, the SIFT GPU algorithm is used to extract features of UAV images, which are used to generate visual words through hierarchical K-means clustering. Secondly, visual words are indexed by using a NSW graph index structure, which is achieved by iteratively selecting a random word and inserting it into the NSW graph, and searching its M nearest vertices that are used to build the edge connection. Finally, the NSW graph structure is implemented on GPU for nearest word searching, and match pair selection is achieved by an efficient algorithm, termed TF-IDF-Match4, for the calculation image similarity scores. The experiments are carried out using three large-scale UAV datasets and compared with the bag of words model algorithms in Colmap and DBoW. The results show that the proposed match pair retrieval algorithm can respectively achieve the speed up ratio of 45 and 18 times compared with Colmap and DBoW, which is provided matching pairs for higher accurate 3D reconstruction.

Key words: image retrieval, vocabulary tree, navigation small world, TF-IDF-Match4 weighted, GPU, the nearest neighbor search

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