The rapid developments in GIS such as data integration, representation, spatial data products, and new spatial data mining methods, are forcing users to deal with data of unknown or ambiguous quality; thus, unpredictable risk in decision making is inevitable. This book addresses some aspects of spatial data quality that have been very scarcely addressed, such as the assessment of quality of products resulting from multiple data sources and quality associated to multi-scale representations. In the era of big data, the mass volume of heterogeneous data and the proper use of the acquired geospatial data remains a significant challenge for GIS users and need to be imediarely investigated.