Objectives of the research presented in this book are addressed in the INSPIRE Directive framework and in the European Spatial Data Infrastructure (ESDI) that is characterized from a growing availability of heterogeneous spatial data that will have to be integrated. The author consider the description of spatial data quality through metadata as an essential task for the implementation of an SDI, whereas current INSPIRE recommendations for metadata specifications have not clearly identified data quality as a major issue. Quality is often regarded as one of the metadata labels, that can be addressed by the users without further specifications. The research focuses on the positional accuracy that could help users to make a more correct evaluation about suitable data for their needs and for their intended application. The analysis of the positional accuracy assessment has resulted in the proposal of new metadata fields to report the positional accuracy element. The proposal is illustrated with support of some outstanding examples of geographic data products, i.e. elevation models coming from LiDAR data and satellite images characterized by different spatial resolutions.