Conceptually,the theory and implementation of“map projection”in geographic information system(GIS)technology is difficult to comprehend for most introductory students and novice users.Compounding this difficulty is ...Conceptually,the theory and implementation of“map projection”in geographic information system(GIS)technology is difficult to comprehend for most introductory students and novice users.Compounding this difficulty is the concept of a“map projection file”that defines map projection parameters of geo-spatial data.The problem of the“missing projection file”appears ubiquitous for all users,especially in practice where data is widely shared.Another common problem is inadvertent misapplication of the“Define Projection”tool that can result in a GIS dataset with an incorrectly defined map projection file.GIS education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors.A novel pedagogical device is introduced in this paper:the seven possible states of GIS data with respect to map projection and definition.The seven possible states are:(1)a projected coordinate system(PCS)that is correctly defined,(2)a PCS that is incorrectly defined,(3)a PCS that is undefined,(4)a geographic coordinate system(GCS)that is correctly defined,(5)a GCS that is incorrectly defined,(6)a GCS that is undefined,and(7)a non-GCS.Recently created automated troubleshooting tools to determine a missing map projection file are discussed.展开更多
基金This research was funded by the USDA National Institute of Food and Agriculture,Hatch Project 1011533.
文摘Conceptually,the theory and implementation of“map projection”in geographic information system(GIS)technology is difficult to comprehend for most introductory students and novice users.Compounding this difficulty is the concept of a“map projection file”that defines map projection parameters of geo-spatial data.The problem of the“missing projection file”appears ubiquitous for all users,especially in practice where data is widely shared.Another common problem is inadvertent misapplication of the“Define Projection”tool that can result in a GIS dataset with an incorrectly defined map projection file.GIS education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors.A novel pedagogical device is introduced in this paper:the seven possible states of GIS data with respect to map projection and definition.The seven possible states are:(1)a projected coordinate system(PCS)that is correctly defined,(2)a PCS that is incorrectly defined,(3)a PCS that is undefined,(4)a geographic coordinate system(GCS)that is correctly defined,(5)a GCS that is incorrectly defined,(6)a GCS that is undefined,and(7)a non-GCS.Recently created automated troubleshooting tools to determine a missing map projection file are discussed.
