SRTM 90 m elevation data for the department of Tolima, Colombia
PROCESSED SRTM DATA
The data distributed here are in ARC GRID format, in decimal degrees and datum WGS84. They are derived from the USGS/NASA SRTM data. CIAT have processed this data to provide seamless continuous topography surfaces. Areas with regions of no data in the original SRTM data have been filled in using interpolation methods. A full technical report on this method is in preparation.
The SRTM data will cover the entire globe with a 3 arc second (approx. 90m) digital elevation model. A 1 arc second data product also exists, but is not available on general release. The data is currently available for small regions for download from the National Map Seamless Data Distribution System, or is available for the entire globe from an ftp site. The vertical error is said to be less than 16m.
The data currently being distributed by NASA contains no data holes where water or heavy shadow prevented the quantification of elevation. These are generally small holes, which nevertheless render the data less useful, especially in fields of hydrological modeling.
The Land Use project, in collaboration with Robert Hijmans (University of California, Berkeley) and Andy Nelson (University of Leeds), have imported the SRTM data, and performed some processing to fill in these no data. This process involved the production of contours, and the re-interpolation of these derived contours back into a DEM. We then used the interpolated DEM values to fill in the original no data holes from the crude SRTM data. This was done using Arc/Info and an AML script which is available for download. Questions regarding the use of this AML should be directed to Andy Jarvis.
Users are prohibited from any commercial, non-free resale, or redistribution without explicit written permission from CIAT. Users should acknowledge CIAT as the source used in the creation of any reports, publications, new data sets, derived products, or services resulting from the use of this data set. CIAT also request reprints of any publications and notification of any redistributing efforts.
NO WARRANTY OR LIABILITY
CIAT provides these data without any warranty of any kind whatsoever, either express or implied, including warranties of merchantability and fitness for a particular purpose. CIAT shall not be liable for incidental, consequential, or special damages arising out of the use of any data downloaded.
We kindly ask any users to cite this data in any published material produced using this data, and if possible link web pages to the CIAT SRTM website (http://gisweb.ciat.cgiar.org/sig/90m_data_tropics.htm).
Citations should be made as follows:
Hole-filled seamless SRTM data V1, 2004, International Centre for Tropical Agriculture (CIAT), available from http://gisweb.ciat.cgiar.org/sig/90m_data_tropics.htm.
