| environ. |
raster One of the two major types of internal data organization used in GIS. Raster systems superimpose a regular grid over the area of interest and associate each cell-or pixel, to use the image term- with one or more data records. The values associated with each grid cell may represent either real values or any scalar or nominal data values associated with the cell coordinates. Among the strengths of the raster method is its ability to accept data directly from remote sensing systems and to represent transitional information. Raster systems tend to be relatively storage-intensive and this imposes practical limits on the area of coverage, the resolution, or both of these. Capacity constraints are, however, becoming less significant as computer memory and storage become more powerful and as data compression techniques become more readily available (GIS中用到的两种主要内部数据组织方式中的一种。光栅系统在感兴趣的地方附加有规律的网格并且关联每个单元或像素，使图像能在一个或多个数据记录中使用。与每个网格单元相关联的值能描述真实的值或与单元坐标相关的标量或标定数据。光栅方法的优点是能直接从远处的传感系统接收数据，并能描述过渡性的信息。光栅系统通常要求的储存容量需求度高，并在覆盖范围或分辨率或这两者上有实现上的限制。然而，当计算机存储变得更强大和数据压缩技术更好用的时候，这些能力上的限制就变得不那么重要。) |
