Satellite Exploration of Thailand > General

Shuttle Radar Topography Mission

SRTM Homepage http://www.jpl.nasa.gov/srtm/ Data File Download ftp://edcsgs9.cr.usgs.gov/pub/data/srtm/

The NASA provides for free download the topographic data of the whole earth, measured by the radar mounted on the Space Shuttle.

The original data is called SRTM-1 (1 second mesh) and has a resolution of 30m. This data is accessible by researchers only. Somewhat reduced version of the data called SRTM-3 (3 second mesh) with a 90m-resolution is provided for public download.

One SRTM data file covers a mesh of 1^o x 1^o (longitude x latitude). It is in the hgt format, and its size is 2,818KB. For download, the data file is compressed in the zip format, and its size varies from 600KB to 2,000KB, depending on the complexity of the topography.

To cover whole Thailand, you need to download some 80 SRTM data files which amount to about 100MB. If your interest and needs are limited to a specific area, downloading one or two data files may suffice.

Example - Around Khao Yai Download File: N14E101.hgt.zip ... 1,404KB Unzipped File: N14E101.hgt ... 2,818KB Area Coverage: N14 - N15 x E101 - E102 Area Coverage Resolution 3D Display

Data Processing

To make any use of SRTM data files, you need some kind of a graphic/GPS/GIS software that can handle the hgt format. Images on this page are processed with a freeware called Kashmir 3D.


Application

The SRTM data itself can produce detailed topographic maps. However, it is best utilized in conjunction with other forms of geo-spatial data.

Example The topographic data can be overlayed on maps. [eg. SmartMap/Thailand, Chiangmai - Samoeng area] + = Example The topographic data can be overlayed on satellite images. [eg. Landsat, Bhumiphol Dam] + =