Design And Compilation Of The Global Land Cover (GL30) Spationtemporal Change Atlas With Consideration Of The Multi-level Organization Of Information

The land cover and its temporal and spatial changes can reflect the distribution and changes of various types of substances on the earth's surface.They are important basic data for global natural resource surveys and ecological environment research,and have important influences on the research of geographic national conditions monitoring,environmental changes and sustainable development.There are multiple sets of land cover atlas for different topics at home and abroad,but there is still a lack of atlases generated by high-resolution basic data.Furthermore,available atlases mainly focus on a single land cover type and a single spatial or time scale so as to be difficult to support the analysis and research of temporal and spatial changes for different fields and different application purposes.In addition,digital atlases in actual use usually adopt information structure organized based on a topic,which is similar to traditional paper atlases.For instance,the information of a provincial traffic atlas is organized based on a "province-city-county" hierarchical structure.In other words,the form of these digital atlases is only a digital-version paper atlas,so as to ignore the different spatial,temporal,and semantic relationships of the land cover information.When using such atlases,users can only obtain information following a fixed hierarchical structure,and unable to obtain much information organized by different structures,e.g.the information organized by different time or spatial scale or semantic hierarchy.Hence,this study proposes an interactive atlas design and compilation method for multilevel information organization with consideration of space,time and semantics,including the visual representations of high,middle and low semantic information designed according to different information types,multi-semantic hierarchical interactive design,and multi-timelevel and multi-space-level related information interaction design,multi-information hierarchical interaction design,and interface interaction design.By the design method,we compiled a global spatiotemporal change digital atlas using Globe Land30(GL30)data with three years(2000 year,2010 year,and 2020 year),which aims to provide a basic and more comprehensive atlases in order to satisfy the requirements from different fields and different users.The research work was supported by a grant from the national Ministry of Science and Technology Fundamental Resources Survey Project "Compilation of Digital Maps of SpatioTemporal Changes in Global Land Cover ".For the complication of global land cover atlas,the specific design work includes:(1)map visualization design based on high,medium,and low semantic levels;(2)relevant information interaction design,including support for multiple spatial levels of global,continent,country,and temperature zone scales,and support for multiple time levels of time points and time periods;(3)the map configuration design,including forward hierarchical layout,radial hierarchical layout and combined hierarchical layout with consideration of the depth of different information levels and the number of multiple information units;(4)digital interface design with consideration of arrangement of interface content considering visual flow and behavioral dynamic interaction.The compilation of the atlas in this study mainly includes:(1)overall design,including content design,map basic layer expression design,appendix and other page design;(2)land cover data processing,including statistic of change types of the land and areas at various scales through cartographic data,by multiprocessing and Arc GIS Python API technologies to generate framing raster category data for three times,and extracting the distribution information of three time(2000 year,2010 year,2020 year)and the change information of three periods(2000-2010 year,2010-2020 year,2000-2020 year)by calculating the value differences among times for same region;(2)basic map generation,including 420 thematic maps generated according different spatial scales(global,continent,temperature zone,and country),and different time(2000 year,2010 year,and 2020 year),and three time periods(2000-2010 year,2010-2020 year,2000-2020 year),and ten types of land cover(Wetland,Water,Artificial,Tundra,Bareland,Forest,Ice,Shrub,Corpland,Grass);(3)digital atlas generation,including: using Arc GIS and HTML technology to product map,using a hierarchical structure to build an atlas data system,through the front-end presentation of atlas content,atlas background management and database management through the backend and other technologies to produce digital environment atlas.The evaluation of the usability of the atlas generated in this study mains consider three aspects,i.e.effectiveness,efficiency,and users' satisfaction,for the interactive functions,and user interface respectively.A structured questionnaire survey method was used in this evaluation experiment and includes 30 questions and participants are asked to give a score for each question according to a 5-grade level.The experiment results indicated that the representations and interactive function of the digital are effective and have high user's satisfaction because the scores given by participants are all more than 4.