Quality Assessment Of Building Footprints In OpenStreetMap And Characteristic Of Its Contributors

The development of Web 2.0 and location technology has made it possible for Internet users to share information based on location.This information is called Volunteer Geography Information(VGI).The emergence of volunteer geographic information provides a wealth of location data and promotes the rapid development of VGI projects,and the most successful VGI project is OpenStreetMap(OSM).OpenStreetMap is the largest opensource geographic information platform with the most users and the most abundant data in the world.It has the advantages of rich data,free openness and high timeliness.However,the lack of a strict and uniform quality control program also causes OSM to have problems such as uneven data quality and uneven data completeness distribution,which affects the application of data.Therefore,it is necessary to deeply understand and grasp the characteristics of OSM data quality.Building footprint is an important layer of OSM and an important basic geographic data.However,the data quality of building footprints,especially completeness of the data,limits its scope of application.At present,the e,valuation method of OSM building footprints completeness only considers the number and area of buildings,but ignores the geometry of the building and cannot fully express the completeness of the building footprints.As producer of data,OSM contributors directly affect the quality of OSM data.At present,there is a lack of analysis and discussion about the relationship between the characteristics of OSM contributors and the completeness of OSM building footprints.In view of this,this paper takes the OSM building footprints as research object,selects southern Finland as research area,proposes an improvement on the OSM building footprints completeness evaluation method,and analyzes the distribution characteristics of completeness.On this basis,the relationship between the characteristics of the OSM contributors of building footprints and the data completeness is explored from the perspective of quantitative features and spatial location characteristics.In general,the main contents of this study include:First,the evaluation method of OSM building footprints completeness is improved,the evaluation index of synthetical completeness is proposed,and the distribution characteristics of synthetical completeness are analyzed.The existing OSM building footprints completeness evaluation methods are sorted out,and pointed out that it only considers the quantity,area or other indicators and ignores the deficiencies of the shape differences.In this regard,based on the area completeness,the shape complexity is introduced as the weight,and a synthetical completeness evaluation method is constructed.Then,combined with the map information measurement method,the quantitative calculation method of synthetical completeness is designed,and the advantages of synthetical completeness are illustrated by the comparison of synthetical completeness and area completeness.On this basis,the distribution characteristics of the synthetical completeness of OSM building footprints are analyzed.Second,the OSM building contributor quantity index system is constructed,and the geographic weighted regression method is used to model the contributor quantity characteristic index system and the synthetical completeness relationship.The index of OSM contributors ignores the insufficiency of contributor contribution imbalance.Starting from the overall characteristics and grouping characteristics of contributor s'contribution,the OSM building contributor quantity characteristic index system is constructed.Then,based on the geographical weighted regression method,the relationship between the number of OSM contributors of building footprints and the synthetical completeness is analyzed,and the influence of each quantitative indicator on the synthetical completeness is analyzed.Third,the spatial location of the OSM contributors of building footprints in the study area are extracted,the spatial location characteristics of the contributors are analyzed,and the correlation between the contributor spatial location characteristics and the synthetical completeness is tested.Based on the phenomenon that the spatial position of the OSM contributors are separated from the drawing area,the spatial position of the contributor of OSM building foorpsints in study area is extracted,and the location extraction efficiency of the OSM contributor is improved by using changesets instead of the node and filtering changesets.By analyzing the location characteristics of OSM building contributors,the global collaboration characteristic in OSM data production are revealed.Non-local contributors also have a non-negligible contribution rate,but have no significant impact on synthetical completeness,while local contributors will significantly improve the synthetical completeness in there nearby regions.