"栅格数据结构压缩存储教案及块码编码原理"

栅格数据是一种常用的地理数据存储形式，栅格PPT学习教案中介绍了栅格数据的压缩存储方法。地理数据通常具有较强的相关性，即相邻像元的值往往是相同的，因此需要进行压缩存储以节省空间。游程编码是一种常用的栅格数据压缩方法，其核心思想是将具有相同属性值的邻近栅格单元合并成一个游程，用一对数字表示，第一个值表示游程长度，第二个值表示游程属性值。每一行都以一个新的游程开始。另一种压缩方法是块码，即将游程扩展到两维情况，将多边形范围划分成具有相同属性的正方形，然后对各个正方形进行编码，数据结构由初始位置、半径和属性代码组成。块码采用方形区域作为记录单元，数据编码由初始位置行列号加上半径，再加上记录单元的属性组成。通过这些压缩存储方法，可以有效地减少地理数据的存储空间，提高数据的传输和处理效率。Traveling Coding - Raster Data Compression SSEMINAR ②  Since geographic data often has strong correlation, that is, the values of adjacent pixels are often the same. Therefore, in order to save storage space, it is necessary to compress and store raster data5 Merging adjacent raster units with the same attribute value together, each merge is called a run. The run is expressed with a pair of numbers, where the first value represents the run length, and the second value represents the run attribute value. Each new row begins with a new run6☞ Block Code (Expanding Run Code to 二D)☞ Block Coding expands the run to two-dimensional situation, divides the polygonal range into several squares with the same attribute, and then encodes each square. ☞ The data structure of block coding consists of the initial position (row and column numbers), radius, and attribute code.块码采用方形区域作为记录单元，数据编码由初始位置行列号加上半径，再加上记录单元的属性组成。0 2 2 5 5 5 5 52 2 2 2 2 5 5 50 0 0 0 0 3 3 32； Through these compression and storage methods, Geographic data can be effectively reduced Storage space to improve data transmission and processing efficiency.