| In the era of Web 2.0,the concept of co-construction,co-governance and sharing has penetrated into all walks of life.In the field of geographic information science,great changes have taken place in the mode of spatial data acquisition and geographic information service,and the general public is gradually involved in the collection of spatial data,which promoted the Volunteer Geographic Information.OpenStreetMap is the geographic information sharing platform with the largest number of volunteers and the richest geographic information in the world.With the advantages of large amount of data,abundant information,high current situation and open-source sharing,it has been widely used.The unique data collection method brings abundant data resources,but also brings many data quality problems.For a long time,many experts and scholars in the field of geographic information science have devoted themselves to the research of OpenStreetMap spatial data quality.A large number of data quality evaluation results show that OpenStreetMap data has little quality problems in terms of location accuracy and data integrity.The main problem lies in the insufficient geometric accuracy of graphic data,which is mainly reflected in the abnormal shape of building objects footprints data.These abnormal figures will not only interfere with map users’ cognition and judgment of actual objects,but also easily lead to the inconsistency between them and adjacent space objects.Therefore,the modification of OpenStreetMap building objects footprints data is a necessary measure to improve its spatial data quality and usability.Through the discussion of OpenStreetMap building objects data,based on the principles and methods of geo-spatial graphics such as geometric calculation method,spatial objects description and similarity,aiming at the general geometric shape problems and special geometric shape problems of building objects,the main contents and contributions of our research are as follows.1.A right angle correction method of building objects based on wall direction is proposed.Introducing the wall direction as a constraint into the right-angle correction process of building objects can not only meet the needs of right-angle correction of building objects,but also keep some non-right-angle features of the building itself.2.A method of building objects arc outline correction based on least square fitting is proposed.Based on the geometric characteristics of the circular arc outline,a set of rules are established to capture its nodes,and then the least square model with restricted conditions is used to fit the circular curve of the nodes,which effectively realizes the modification of the circular arc outline of the building objects.3.The software of building target contour correction is designed.Under the development environment of Microsoft Visual Studio 2012,a set of building target outline correction software was developed by integrating embedded component library AE and visual development language C#. |
