Study on Sampling Inspection Schemes to Digital Products in GIS

Spatial data is the basis of the GIS and non-spatial data is intention and the description of geographic cell.The quality of data affects greatly on the result of application analysis and the realization of the practical target in GIS.The quality of the GIS data must be taken into accacnt in the procedures of data collection, processing and operation. With the development of digital products and industrialization of GIS, more and more digital products appear on the surveying market and become the basis of applications.But for economical reasons a producer or purchaser of large database cannot perform manual check for the complete amount of data.Nevertheless, he or she should carry out some type of quality control specification and evaluation to the quality of digital products.The inspection can be done by drawing random samples, checking the objects within each sample very carefully and concluding from the result on the complete dataset using statistical method.Very often sampling methods are used for randomly checking purchased geodata, but very seldom these checks are based on solid statistical theory.So with the development of the standard of quality management and quality guaranty, the requirement of scientific inspection to digital products should be update.At present, there are about 20 national standards published on sampling inspection, which play a fine directorial role in practice.The theory of quality of control and inspection can't be used for GIS production perfectly unless the concept, range of the application, method and procedure of these standards have further been studied on making a good basis for the development of the industrialization in GIS. The sampling inspection can provide reliable information for the quality management of products.As a basic means of quality control, it is also very important to study the sampling inspection for quality management of GIS products.For the digital surveying product it is a key component in digital surveying products, adopting a principle of "check-accept for the first rank, inspection for the second rank".This paper briefly discusses the rationale of the sampling inspection method and the sampling inspection schemes to the digital product.The OC curve is also drawn to explain the deficiency of the percent sampling procedures for inspection.Meanwhile, the method of one time limiting quality of count selection is raised as the inspection scheme for production departments while the method of one time after-inspection average percent defective upper limit of count selection is proposed for acceptance departments.These two schemes are in agreement with exiting percent sampling inspection schemes in certain circumstances, and have the advantage that can be easily conducted.More contents and quality characteristics have been involved in the digital product in GIS, and the model of sampling inspections still need a further research.The result of the research can be used in different sampling levels and suited for variant and complex digital products, and ensure the reliability of sampling while make the fee of sampling minimum.