{'fraction_non_alphanumeric': 0.01845018450184502, 'fraction_numerical': 0.0007380073800738007, 'mean_word_length': 5.135746606334842, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
AN ALGEBRA FOR OPENGIS ® COVERAGES BASED ON TOPOLOGICAL PREDICATES

Map algebra is a collection of functions for handling spatial datasets where each data contains a set of geometries of the same type which bound to a geographical reference. The current theory for Map Algebra uses ad hoc operators proposed by Dana Tomlin. His proposal has had great practical success, and most GIS implementations provide its operations. However, there is a lack of theoretical foundations for the operations proposed in Tomlin’s map algebra. This is a limitation for the proposal of international standards for map algebra. Specifically, the Open Geospatial Consortium’s proposal for handling a map (the coverage data type) lacks a set of functions to manipulate its content. To address this problem, our work proposes a specification for an algebra for Open GIS coverages which uses a dimension-extended version of Egenhofer and Herring’s 9-intersection predicates to express spatial operations. The proposed coverage algebra includes all Tomlin’s functions, as well as operations that are not part of Tomlin’s algebra, but are useful in practice. Our proposal could be the basis for setting up standard for operations on Open GIS coverages. The use of standards for operations in coverages would be a significant advance for increased interoperability of spatial data