SRTM Converter

This addon is for LandSerf 2.0 only. It has been incorporated into later versions so you should not need download it. It is retained here for users who need to use version 2.0 but would like the extra functionality.

For the latest release please visit

Utility to convert Shuttle Radar Topography Mission (SRTM) DEMs into LandSerf format.

SRTM DEM of Northern England


SRTM DEMs at a 3 arc-second resolution (~90m at the equator) are freely available for most of the globe. Additionally, 1 arc second (~30m at the equator) SRTM DEMs are available in various formats for the continental United States.

SRTM data are often distributed in '.hgt' format as described in the SRTM documentation. Data for the United States are also distributed in other raster formats from the USGS seamless data server. HGT format data for Europe, Asia, North and South America can be found at

Installation Instructions

To install the SRTM converter download the appropriate file below and uncompress into your LandSerf installation folder (e.g. c:\landserf200). This should create a sub-folder called addons with several files including SRTMConvert.bat and

Running SRTMConvert

To run SRTMConvert, open a command prompt in Windows (Start menu->Run...->cmd) and then change to the directory in which the converter is installed (e.g. cd \landserf200\addons) and type SRTMConvert srtmFileName [removeVoids] where srtmFileName is the SRTM '.hgt' file to convert. If you wish to remove voids (missing data) from the surface, you can optionally include the removeVoids parameter. This will interpolate any missing values based on known neighbouring cell values.


SRTMConvert c:\data\surface.hgt (Windows)
SRTMConvert c:\data\surface.hgt removeVoids (Windows)

./ ~/data/surface.hgt (Unix)
./ ~/data/surface.hgt removeVoids(Unix)

Running the converter will create a new file called surface.srf in the same directory as the .hgt file. Note that the name of the file is important since this contains information about the location of the DEM. For example, N55W003.hgt refers to a DEM with an origin at 55 degrees North, and 3 degrees West.


You will probably need to reproject the converted surfaces into UTM or OSGB coordinate systems in order to perform useful analysis within LandSerf. When reprojecting within LandSerf, make sure the interpolate to new resolution box is selected. Note that the unprojected north-south resolution of the original data is fixed (e.g. about 92m for the 3 arc-second data), but the east-west resolution dependent on latitude (e.g. varying from about 90-40m for the 3 arc-second data).

SRTM .hgt data are provided as tiles. To combine more than one tile into a single LandSerf raster, convert each one separately, load at least two of them into LandSerf making sure one is selected as the primary raster, the other as secondary raster and then select Edit->Combine Rasters.... Make sure you select the Union option for combination. The new combined raster from this process can then be combined with further converted tiles. It is recommended that you project the data onto UTM/OSGB after combining tiles. The figure above shows 9 tiles of Northern England combined into a single DEM.