A metadata-based approach to define a standard to visual queries in GIS

This article proposes a framework that creates a standard to formulate visual queries in geographical information systems (GIS). The queries use visual elements and visual spatial operators, where each element is represented according to a geographic data visual standard. This standard is proposed to be based on a digital geospatial metadata standard, and based on it we define a new geographic visual query language to be used in GIS. The main objective of the proposed framework is to improve the friendliness of a GIS interface, which is achieved by using pictorial information to build query clauses and by reducing the differences among GIS internal structures, using this visual standard.