A Siamese neural network for learning the similarity metrics of linear features

Abstract Measuring similarity is essential for classifying, clustering, retrieving, and matching linear features in geospatial data. However, the complexity of linear features challenges the formalization of characteristics and determination of the weight of each characteristic in similarity measurements. Additionally, traditional methods have limited adaptability to the variety of linear features. To address these challenges, this study proposes a metric learning model that learns similarity metrics directly from linear features. The model’s ability to learn allows no pre-determined characteristics and supports adaptability to different levels of complex linear features. LineStringNet functions as a feature encoder that maps vector lines to embeddings without format conversion or feature engineering. With a Siamese architecture, the learning process minimizes the contrastive loss, which brings similar pairs closer and pushes dissimilar pairs away in the embedding space. Finally, the proposed model calculates the Euclidean distance to measure the similarity between learned embeddings. Experiments on common linear features and building shapes indicated that the learned similarity metrics effectively supported retrieving, matching, and classifying lines and polygons, with higher precision and accuracy than traditional measures. Furthermore, the model ensures desired metric properties, including rotation and starting point invariances, by adjusting labeling strategies or preprocessing input data.