自从SRTM成功实施以后,各国都加大了对于SAR技术的研究,美国、欧盟等相继发射了相关卫星,目前的公开的标称精度已达到
DEM是USGS制定的数字高程官方标准,网上可以公开下载,加起来100多页 USGS制定的DEM标准,为了与讨论的话题接近,我就画繁为简,通俗简单的描述一下,以1度区域的数据为例子:1度==3600秒,SRTM-1(1弧秒)精度的数据是将1度的面积分成了3600x3600个小区域,每一个小区域的大小是1弧秒(约30x
SRTM与DEM的关系,SRTM仅仅是获取地形数据的方法之一,而且SRTM的数据结构与DEM类似,转换起来很容易。其他的如立体像对也能获取DEM数据,如ASTER的DEM水平采样精度大约
SRTM的数据是用16位的数值表示高程数值的(-/+/
关于DEM数据的精度,USGS有相关的数据可以作参考,大体上1度的幅面(1度、30分、15分、7.5分等是地图幅面的区别,幅面越小,精度越高)采用的是3弧秒精度的数据,精度是1:250000,30分幅面的数据用的2弧秒精度的数据,精度是1:100000,15分的数据用2弧秒精度(Alaska:阿拉斯加州用)1:63366,7.5分的数据用1弧秒或1/3弧秒(水平采样精度
National Imagery and Mapping Agency’s(NIMA )国家图像和测绘局:主管军用测绘和照相侦察两方面的事务,受美国国防部指挥。他制定DIGITAL TERRAIN ELEVATION DATA(DTEM)的标准包括了SRTM:
现摘录部分章节如下:
Scope. This specification defines the requirements within
National Imagery and Mapping Agency’s (NIMA) Digital Terrain Elevation Data
Base which supports various weapon and training systems. This edition
includes the Shuttle Radar Topography Mission (SRTM) DTED Level 1 and Level 2
requirements.
3.3.1.1 Absolute accuracy.
3.3.1.1.1 Absolute horizontal accuracy.
90% Circular Error (C.E.) World Geodetic System (WGS) < 50 meters
3.3.1.1.2 Absolute vertical accuracy.
90% Linear Error (L.E.) Mean Sea Level (MSL) ≤ 30 meters
3.3.1.2 Relative vertical accuracy (point-to-point).
90% L.E. MSL ≤20 meters over a 1° cell
3.3.2 DTED Level 2 accuracy.
3.3.2.1 Absolute accuracy.
3.3.2.1.1 Absolute horizontal accuracy.
90% Circular Error (C.E.) World Geodetic System (WGS) ≤ 23 meters
3.3.2.1.2 Absolute vertical accuracy.
90% Linear Error (L.E.) Mean Sea Level (MSL) ≤ 18 meters
3.3.2.2 Relative vertical accuracy (point-to-point).
90% L.E. MSL ≤ 12 meters over a 1° cell for low and medium
terrain (0 to 20% predominant slope).
90% L.E. MSL ≤ 15 meters over a 1° cell for high relief terrain
er than 20% predominant slope).
T3.10.9.4SRTM Accuracies. The SRTM DTED Level 2 has a system design 16
meter absolute vertical height accuracy, 10 meters relative vertical height
accuracy and 20 meter absolute horizontal circular accuracy. All accuracies
are at the 90% level. Individual SRTM DTED Level 2 cells have an accuracy
recorded in the ACC record calculated from the collection parameters. These
values will differ from the system design accuracies.(系统的设计精度更高一些)
说明:Level 2是1弧秒的SRTM,Level 1是3弧秒的SRTM数据
可以点击链接选择
Performance Specification Digital Terrain Elevation Data (DTED®)或者
直接点击链接 因为MIL的后缀,与军事有关可能部分地区上不了所以我特意选择了部分同精度有关的部分。