ZY3-02 is the first satellite equipped with a laser altimeter for earth observation in China.This laser altimeter is an experimental payload for land elevation measurement experiment. The new technical production system has been successfully implemented in national campaign to update 1: 50 000 topographic database. Based on the above, a technical system for large scale updating production, mainly including image based updating software and data generalization based updating software, has been developed and equipped to a large number of production units. High resolution image-based updating and large-scale data generalization-based updating were developed and used as two majors updating techniques, a series of technical production specifications were made. This paper outlines the master design and technical development of this national updating engineering, which adopts a full coverage updating strategy characterized by all element topographic data modeling, change detection in all related areas, and whole process data quality controlling. In order to improve the quality of geographic information service, State Bureau of Surveying and Mapping of China had launched a five year's national campaign to update 1: 50 000 topographic database. The currency of geographic data refers to its consistency with respect to the real world, and plays a critical role in geographic information service and applications. We also believe that the conclusions we got in this paper are valuable for how to select an appropriate classifier in the similar applications. Therefore, we make the land cover classification test over China using DTC and MLC methods and compare them again. Through the comparison, we got the conclusions: DTC is the best, and MLC as one of the classical methods is more stable than other three methods. Then, we compare the four classifiers through different aspects. The emphasis is placed on the comparison of the four classification methods and the techniques used for improving classification accuracy. Therefore, the four broadly used classification methods, which are Maximum Likelihood Classification (MLC), Self-Organized neural network (SONN), Support Vector Machine (SVM) and Decision Tree Classification (DTC) are firstly applied for the land cover Remote Sensing classification based on the multitemporal Moderate Resolution Imaging Spectroradiometer (MODIS) images of Heilongjiang area. In recent years, non-parametric classifiers such as the neural network, the decision tree classifier and other classifiers have developed increasingly. Since the first resource satellite was launched in 1972, the remote sensing community has witnessed the impressive progress in image classification methods, which is primarily driven by the advancement of remote sensing technology and computer technology. ![]() Land cover classification is a complex process that may be affected by many factors.
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