QUALITY ASSESSMENT – EXAMPLE OF DIGITAL PRODUCTS OF FUNDAMENTAL GEOGRAPHIC INFORMATION OF CHINA
Digital products of fundamental geographic information are the main components of Digital China Geo-spatial Framework (DCGSF for short). More and more mass data were produced and distributed to various users by different agencies and organizations with continuous implementation of fundamental surveying and mapping activities and various specified projects within national Administration of Surveying, Mapping & Geoinformation. Therefore, what about the description and quality assessment used for these products will directly effect the acquisition, delivery, share, and application of data. A quality model, by which quality is assessed through 3 levels of classification of quality elements, quality subelements, and check items, was built in this paper based on ISO 19113 and ISO 19114 so that to make the quality of digital products of fundamental geographic information to be assessed reasonably, and to make the quality assessment tools to be operable in practice. Quality assessment methods respectively for each of quality elements, quality subelements, and check items are presented. Fundamental data of Digital Line Graphs, Digital Elevation Models, Digital Orthophoto Maps, and Digital Raster Maps at the scale of 1:50,000 in DCGSF were used as examples to determine the quality of 9 quality elements, 24 quality subelements, and 68 check items considering the contents and the requirements of various users for these data, as well as the practical experiences in quality assessment. 300 DLGs selected from national key projects of surveying and mapping engineering were used for testing to validate the operability of the results mentioned in this paper. Random sampling is used, when sampling, for each layer, which is layered based on production unit and level of difficulty. Quality checking and quality assessment, and statistical analysis was done for samples in terms of item product and lot products respectively. The results from this test indicated that quality model and quality assessment methods introduced in this paper is of good operability, and results from it are reasonably good. Finally, the quality model and quality assessment methods introduced in this paper is applied in the development of national standards.