无边界游程编码及其矢栅直接相互转换算法

NONBOUNDARY RUNLENGTH ENCODING SYSTEM FOR RASTER AND ITS RELEVANT ALGORITHMS

本文提出了无边界游程（ＮＢＲＬ）编码的栅格压缩格式及其与矢量格式之间直接相互转换的算法。无边界游程编码具有无矩形边框限制的特点，可随意扩展而无须改变整体参数，特别适合范围不同的两个栅格的各种组合运算。提出的提取多边形算法，可直接在游程上作标记，而不必先还原成非压缩格式，从而节省了内存，提高了速度。

A new runlength encoding system for compression of raster data, NonBoundary RunLength(NBRL) encoding system, together with algorithms for direct transformation between vector data and compressed raster, are proposed in this paper. The code eliminates the limitation of rectangle boundary, which makes it easy for two raster of different size to fulfill various combination operations. The algorithm of directly extracting polygon from the compressed raster, taking the advantage of to label on runlength freely, leaves out the step of restoring NBRL to noncompressed format and gains high efficiency.