A Similarity Metric Method for Contour Line Groups Considering Terrain Features

Contour lines, as the primary elements of fundamental geospatial data, have long been a research focus for similarity measurement. With the evolution of cartographic generalization, the representation of contour lines across varying scales must maintain the consistency of specific information. Typically, the rationality of the generated results is assessed based on their similarity values. However, current measurements for measuring contour similarity predominantly focus on geometric and topological aspects, and are often less concerned with the terrain-specific similarities that are intrinsic to contour lines. Contour line groups contain a wealth of topographic information, and the similarity of their terrain features reflects both the variations in relief and the intrinsic nature of landform development. In this study, we propose a novel metric for assessing the similarity of contour line groups by considering topographic features, aiming to evaluate the similarity of contour line groups from a holistic perspective. First, we analyze and define the geometric, topological, and topographic similarity calculation metrics for contour line groups. Next, we apply the Analytic Hierarchy Process using ten criteria, which are encompassed by these three similarity metrics. To validate the effectiveness of the proposed metric, we select hillock areas within Suide County, China, as a case study for examining the similarity of contour line groups. The results demonstrate that the proposed metric provides a more precise quantitative framework for delineating the subtle differences and similarities among multi-source and multi-scale contour line groups within the overall similarity. Moreover, the metric also establishes a foundation for the quantitative assessment of surface morphology and the classification of geomorphological types.