Theories And Methods Of Data Quality Control In Construction And Management GIS

Data quality issue and quality control technique of GIS data are the most focusing problems in current research and application of GIS. The contents of data quality control are very comprehensive,including all the technologies and activities to meet the requirements of data quality. In this paper,the theories and techniques of data quality control are thoroughly studied by taking Pudong construction and management Geographic Information System(JS-GIS),including error analysis and accuracy evaluation of digitized data,sample tests of housing surveying product,the principle and method of disfigurement measurement of attribute data based on sampling theories,and total quality control techniques of GIS data. These methods are implemented in the construction of JS-GIS. The main contents are as follow:1. The components of JS-GIS are introduced,and data sources and data capture methods are in JS-GIS are analyzed.2. The characters between scan map digitization and manual digitization are compared. The error sources of cadastral map digitization are analyzed. The error analysis and error distribution tests shows that the error in scan map digitization is almost the same as that in manual digitization. The error distribution in scan digitization may not obey the normal distribution,and is greatly affected by the systematic error.The correlation of digitized coordinates in cadastral map digitization is analyzed by calculating the coefficients among the grids composed of the digitized coordinates.Based on this,the digitized data are adjusted by considering their correlation. The results show that the correlation between digitized coordinates is obvious. Therefore,in order to evaluate the accuracy of digitized data pertinently,it is necessary to process them by correlation adjustment.3. The methods of check and inspection of newly added housing surveying data are studied. According to the characters of housing surveying,the quality elements of inspection are determined,the method of division of the sample unit is proposed to inspect the digital housing flat map,and the sample inspection themes are presented to check the housing surveying products. The normal theme is provided,and the detailed measures of inspection are established in JS-GIS.4. The disfigurements of the attribute data are defined as four kinds. The calculation formulas and sampling themes are derived. Based on the sampling error in the normal random sampling and layered sampling,the methods of determining sample volume and selecting of sampling themes are studied. By analyzing the attribute data in JS-GIS,the attribute data types are divided,and the corresponding sampling themes are presented.5. According to the view of total quality control,the quality control techniques in data capture,data maintenance and data update are proposed,and the procedures of total quality control in JS-GIS data construction are discussed.