中国地区SRTM DEM数据集（2000）

SRTM的传感器有两个波段，分别是C波段和X波段，我们现在使用的SRTM都自于C波段。公开发布的SRTM数字高程产品包括三种不同分辨率的DEM 数据:
* SRTM1 覆盖范围仅仅包括美国大陆,其空间分辨率为1s ;
* SRTM3 数据覆盖全球, 空间分辨率为3s,这是目前使用最为广泛的数据集，SRTM3的高程基准是EGM96的大地水准面，平面基准是WGS84；标称绝对高程精度是±16m，绝对平面精度是±20m。
* SRTM30 数据同样覆盖全球 ,分辨率是30s.
SRTM数据存在多个版本，早期的SRTM数据由NASA“喷气推进实验室”(JPL ,Jet Propulsion Laboratory)地面数据处理系统( GDPS)来完成的，数据被称为SRTM3-1。美国国家地理空间情报局对数据做了更进一步的处理，缺少情况得到明显改进，数据称为SRTM3-2。
该数据集主要是第四版本由 CIAT（国际热带农业中心）利用新的插值算法得到的SRTM地形数据，此方法更好的填补了SRTM 90的数据空洞。插值算法来自于Reuter et al.（2007） SRTM的数据组织方式为：每5度经纬度方格划分一个文件，共分为24行（-60至60度）和72列（-180至180度）。文件命名规则为srtm_XX_YY.zip，XX表示列数（01-72），YY表示行数（01-24）。
数据分辨率90米
数据使用:SRTM的数据是用16位的数值表示高程数值的（-/+/32767米），最大的正高程9000米，负高程（海平面以下12000米）。空数据用-32767标准

The SRTM sensor is equipped with two bands: C-band and X-band. All currently deployed SRTM datasets originate from the C-band. The publicly released SRTM digital elevation products include three DEM datasets with varying spatial resolutions:
* SRTM1: Covers only the contiguous United States, with a spatial resolution of 1 arc-second.
* SRTM3: Covers the entire globe, with a spatial resolution of 3 arc-seconds. This is the most widely used dataset to date. The elevation datum of SRTM3 is the EGM96 geoid, and its horizontal datum follows WGS84. Its nominal absolute elevation accuracy is ±16 m, with an absolute planar accuracy of ±20 m.
* SRTM30: Also covers the entire globe, with a spatial resolution of 30 arc-seconds.

There are multiple versions of SRTM data. Early SRTM data were processed via NASA's Jet Propulsion Laboratory (JPL) Ground Data Processing System (GDPS), and the resulting dataset was designated SRTM3-1. The United States National Geospatial-Intelligence Agency further processed the data, which significantly mitigated data voids, and the revised dataset was named SRTM3-2.

The primary version of this dataset is the 4th iteration of SRTM topographic data developed by the International Center for Tropical Agriculture (CIAT) using a novel interpolation algorithm, which better fills the data gaps in SRTM 90. The interpolation method is derived from Reuter et al. (2007).

The SRTM data are organized by dividing the global grid into 5°×5° latitude-longitude tiles, totaling 24 rows (ranging from -60° to 60° latitude) and 72 columns (ranging from -180° to 180° longitude). The file naming convention is "srtm_XX_YY.zip", where XX denotes the column number (01-72) and YY denotes the row number (01-24).

The data has a spatial resolution of 90 meters.

For data usage: SRTM uses 16-bit signed integers to represent elevation values, with a value range of -32767 m to +32767 m. The maximum recorded positive elevation is 9000 m, and the minimum negative elevation (below sea level) is -12000 m. Missing data is standardized as -32767.