Ensuring the Semantic Correctness of Complex Regions

Ensuring the semantic and topological correctness of spatial data is an important requirement in geographical information systems and spatial database systems in order to preserve spatial data quality and enable correct operation execution. Spatial objects like complex regions are usually represented as an ordered sequence of segments (sequence view) to support and ease the computation of spatial operations by means of plane sweep algorithms. The semantic correctness of such a sequence is usually simply assumed but is not easy to see.