Research On Integration Of Land Polygon And Multi-source Online Maps Based On Multi-scale Matching

land polygon is a single land type block divided by administrative boundary,ownership boundary and single linear feature.It is an important land resource information,which is closely related to people's production and life.On the one hand,the country has spent a lot of manpower and material resources to conduct land surveys for many times,and each land management departments have accumulated massive,accurate and abundant land polygon data which have not been fully socialized.At the same time,there are many open,free and real-time online map services on the network,which integrate massive geographic information resources.but the way of combine these online maps with land polygon is not convenient at present.On the other hand,relevant government departments and the public need the integration information of land polygon and multi-source online maps,but the acquirement way is relatively lacking.Therefore,study a way to integrate land polygon with multi-source online maps can reduce the above limitations effectively.Aiming at the integration requirements of land polygon and multi-source online maps,this paper takes Tianditu,Baidu map and Google Earth as examples to carry out multi-scale matching integration research on land polygon and three online maps.Based on the research and analysis of coordinate matching and visual scale matching,a snapshot tool was designed and developed to obtain the integratedinformation of multi-scale matching integration land polygon and three online maps.The main research and conclusions of this paper are as follows:(1)the integration of land polygon and three online maps could not be performed because of coordinate mismatch,rough matching was studied under the condition of accuracy of 10 meters.The rough coordinate matching between land polygon and Tianditu is realized by using gaussian inverse calculation.This paper focuses on the influence of five grid size and five coordinate matching methods on the coordinate matching accuracy of land polygon and Baidu map,and through comparison,it is concluded that 8×8 grid combined with second-order polynomial method should be used to achieve coordinate rough matching between land polygon and Baidu map.It is verified that when the accuracy requirement is meter level,the coordinate is basically compatible between land polygon and Google Earth.(2)Based on the coordinate rough matching integration of land polygon and three online maps,in order to obtain multi-scale matching integration information,and a matching method based on view range as the matching basis and the pixel distance as the matching criterion is proposed to realize multi-level visual scale coarse matching of three online maps.The results show that longitude has basically no effect on the visual scale matching relationship of the three online maps,whilelatitude has a greater influence on the visual scale matching relationship between Tianditu,Baidu Map and Google Earth.The visualization scale of Tianditu and Baidu map has a constant proportional relationship,and the scale coefficient is about 1.673.In the latitude of a city,the Google Earth height corresponding to the upper level is basically twice that of the next level whether Tianditu or Baidu map.The Google Earth height corresponding to the 18th-level Tianditu decreases linearly with the increasing latitude,Baidu map is the same.By synthesizing the visualization scale empirical formulas of three online maps,it is possible to simultaneously realize visualization scale matching of three online maps at different latitudes and different longitudes and different levels.(3)Based on the research results of coordinate matching and visualization scale matching.In the Microsoft Visual Studio 2013 development environment,using C# as the development language,the author designed and developed a snapshot tool to obtain multi-scale matching integrated information of land polygon and three online maps,mainly including multi-type snapshot,multi-scale snapshot,snapshot picture meta data acquisition,manual intervention and traversal quality inspection four functions.