平面影像到QTM像元的转换算法及精度分析

平面影像数据到四元三角网(Quaternary Triangular Mesh,QTM)像元的转换是实现全球QTM格网影像无缝建模的首要任务。提出基于面积权的数据转换方法,给出不同类型的权重及格网值的计算,并利用ArcGIS中256级灰度的Wsiearth.tif图像数据分析了转换精度。结果表明:将4 km分辨率的影像数据转换到12层的QTM像元时,转换误差在0~2灰度内占96.27%,对一般应用的影响可以忽略不计。

An Algorithm and Its Precision Analysis for the Transforming of Image into QTM Pixels

Transforming image to QTM pixels is the base of global seamless image model with QTM data structure.A transforming algorithm based on the weights of QTM and image pixel intersection areas is developed in this paper.The detailed transformation steps is as follows:firstly,QTM is projected onto image projection plane;then according to the relation of QTM vertexes and plane pixels,four intersection cases of QTM and pixels are presented and the intersection areas of QTM and pixels are computed respectively;next,the values of QTM are computed based on intersection area weights.In the end,the experiment on data transformation error by using of Wsiearth.tif data with 256 grey levels in ArcGIS is done.The results indicate that the transformation error in two grey levels is 96.27% at 12-level QTM,which is available for general applications.