Data quality of Global Map and some possibilities/limitations for its wide utilisation for global issues

摘要

Global Map (GM) was born as a product to replace previous IMW (1:1 000 000) with a new map in digital form with the homogeneous standards for entire globe. The primary objective of GM is to contribute to the sustainable development through the provision of base framework geographic dataset as necessary for better understanding the current situation and changes of environment at a global level. The GM datasets encompass the entire globe at a scale of 1 :1 000 000 (for vector data) and spatial resolution of 30 arc seconds (for raster data). Global Map with its consistent quality and data standards is a handy tool to monitor the environmental status at regional and global scale, which may have limited uses at national and local scales. It also provides a framework within which the local environmental problems can be modelled and analysed with appropriate data. Disaster prevention, disaster mitigation, preserving biodiversity, promoting regeneration processes of the ecosystem, etc. are some of GM targets. Due to fact that the GM data from geometrical point of view are basically partially topological and non-harmonised data coming from different sources (NMOs), our efforts for its utilisation for map compilation and spatial analyses resulted with limitations because of overlaps and gaps between the polygons, as well as non-spatial joint between the line objects. The GM specification allows to each participant to use different sources with different quality for different areas of their countries and for different layers. This type of definition of non-homogeneous accuracy without any process of data harmonisation in some way allows overlaps, gaps, and non-spatial joint of data not only between different countries, but the data within the same country and between different layers. The relation between the data of raster and vector layers, resulted with big differences, basically because of non-homogenous accuracy between the vector and raster data, and non-harmonised data, as well as because of the differences on the defining of the level zero from the participant countries. The above situation can be overcome by including the data harmonisation process as a necessary step during the process of preparing the GM data, which should be defined in GM specification. This process might be very difficult, because of some mentioned political problems above; however, it is a necessary step for better future of Global Mapping project and wide utilisation of GM data.