GeoTiff中GeoTag域解析

Analysis of GeoTag Fields in GeoTiff

GeoTiff是Tiff格式的一种特殊形式 ,1.0版的GeoTiff在Tiff格式的基础上增加了 6个GeoTag(地理标志 )域来描述栅格影像对应的地理坐标信息和投影信息 ,并利用像元比例、结点、投影类型、坐标系统、椭球参数等 ,准确地实现了影像栅格坐标与地理坐标之间的相互转换 .首先介绍了GeoTiff所支持的 3种坐标空间 ,并在剖析其六大地理标志域间相互关系的基础上 ,详细描述了各个标志域的具体含义及其在影像中的存储组织 ;其后根据GeoTiff的影像数据地理编码的原理 ,给出了栅格空间与模型空间之间坐标转换的方法和步骤 ;结合GeoTiff的应用 ,阐述了GeoTiff的优点 ,并对它的应用前景做出了展望 .

GeoTiff is a special form of Tiff spec. GeoTiff 1.0 adds six GeoTags provided to describe all geographic coordinate information and projection information on the base of Tiff. Using the tags, such as pixel scale, tie points, projection types, coordinate systems etc., you can easily get the latitude and longitude from the raster space of GeoTiff image, and vice versa. Firstly, this thesis introduces three kinds of coordinate systems GeoTiff supporting and discusses the relationships of the six GeoTags; next it describes the meanings and the storing method of them. Then, the thesis gives the method and steps of the conversion between coordinates of raster space and model space according to the principle of GeoTiff image data encoding. Finally, considering the application of GeoTiff, the thesis discusses its merits and forecasts its development scope.