Follow this link for my Microsoft Silverlight Shuttle Radar Topography Mission (SRTM) HGT file viewer web page.

This web page can display 90 metre 3 arc second SRTM HGT files. These are available from . You should download the files you want and unzip them to your local disk before using them. You can also view PNG or JPG image files in this web page. This web page requires Microsoft Silverlight version 3.0 and .Net framework 3.5. For more information about Microsoft Silverlight see the web site. Silverlight version 3.0 is a browser addin that will run in all the main browsers. In my SRTM viewer web page there are a variety of colour schemes available from the Colour Scheme menu. Some give good results for low level land. Others are more suitable for high level land. When using the slider controls drag and release the sliders to redraw the image. This web page is best viewed at a screen resolution of 1280 * 1024 or better.

Screen shot.

strm viewer

To open a SRTM HGT file click the Open SRTM HGT unzipped file button and choose a file that you have previously downloaded and unzipped.

There are several colour schemes available which can be selected with the Colour Scheme dropdown.

colour scheme


The Zoom, Vertical shift and Horizontal shift sliders are operated by dragging and releasing the sliders.  They only effect the view of SRTM files and not PNG files. They allow you to zoom into and view an area of  the SRTM file.  When you save the SRTM as a PNG image file they set the area that is saved. If you click the Zoom or Shift sliders rather than using drag and release you need to click the Redraw button to update the screen. The mouse over info will be misaligned until you do this. Using click of the shift sliders and then the Redraw button can be useful for fine alignment of the image when you are using a lot of zoom.


The Image size slider sets the size of the image on screen.

The Latitude slider adjusts the proportions of the SRTM image to the correct ratio for it's latitude.  SRTM files contain a 1201 by 1201 pixel area regardless of their latitude. The latitude slider is automatically set when you load an SRTM file to the value of the second and third digits of the file name.  If you manually set the Latitude slider then the longitude value displayed for the mouse position will be incorrect. Reload the SRTM file if you want to reset the Latitude slider back to it's auto position.


The Open PNG file button allows you to open and display a PNG image file.  You can not change the colour or zoom into a PNG image or resave it.


The Save as PNG button allows you to save the SRTM as an PNG image file and chose the saved location.    The Zoom and Shift sliders set the contents of the saved PNG image file.


The Save as PNG to IsolatedStorage button allows you to save the SRTM as an PNG image file in the isolated storage area.  Silverlight restricts where the application can save files to on your local drive. The isolated storage area is several folders below \Documents and Settings\...\Local Settings\Application Data\Microsoft\Silverlight\ .  To use your saved PNG file you will need to locate it with a search from the Silverlight folder.  The Local Settings folder is hidden so you may need to change your Explorer settings to show hidden folders.  The Zoom and Shift sliders set the contents of the saved PNG image file.


When you save an SRTM as an PNG image file in the isolated storage area you may be prompted to increase the available storage space.  If you do not want to increase the available storage you could instead delete some of the existing files in the storage yourself or right click the web page and use the Silverlight configuration utility to delete all the files.


When the mouse is over the image the latitude, longitude and height at the mouse position are displayed.  Left clicking the image copies that information into the text box near the top left corner of the window.  The latitude and longitude are WGS84 and the height is in metres.


Right clicking the web page opens the Silverlight configuration dialog or allows you to install the web page as a standalone program on your PC.

To uninstall the web page as a standalone program on your PC. Start the program and then right click on the window and choose Remove this application.

FlashGet a downloader program that I installed on my PC caused IE to crash when I loaded my Silverlight web page. It was ok once I had uninstalled the offending program. So if you find Silverlight crashes check any addins that you have installed. The crash error window should give you an indication to which program is causing the problem.

A utility to fix USB GPS jumping mouse problems.

GPSSC Laptop safety camera detector software.
© Steve Matthews
Last updated 12-July-2009.