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SRTM data and Digital Elevation Model anyone??

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  • 28-07-2009 7:38pm
    #1
    WithCheesePlease
    Registered Users Posts: 1,006 ✭✭✭


    Not sure if this is the correct forum for this, may belong in a science forum but I'll try anyway...

    Does anyone know about the Shuttle Radar Topography Mission (SRTM) elevation data?? Basically, I'm just wondering how I can look at the raw binary .hgt files if anyone has any clue? I don't want to view them in ArcView or whatever, would just like some way to pretty much double click in to view the raw binary data that's contained within. Like to view it in notepad with all the lat / long points and elevation (in binary or whatever).

    Can anyone help me out with this??
    Tagged:


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    #2
    Alun
    Registered Users Posts: 21,466 ✭✭✭✭Alun


    They're just binary files ... 1201 x 1201 (for the 3 arc second tiles) 16 bit signed integers in big-endian format (AKA 'motorola' format, most significant byte first, i.e. the opposite of 'Intel' format). Values are the height in metres above the WGS84 reference ellipsoid. The values are stored in row major format, i.e. first 1201 integers are row 1, next 1201 are row 2 etc. -32767 represents a void. Each file represents a 1x1 degree tile.

    The 1 arc second version is bigger, i.e. 3601 x 3601 integers.

    EDIT: OP, what are you trying to do with the data exactly?


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    #3
    WithCheesePlease
    Registered Users Posts: 1,006 ✭✭✭WithCheesePlease


    Thanks Alun.

    But yeah, I know what's in the file, I just want to see into the file. Actually see the binary.

    The reason being - just a project I'm working on myself. I know there are web services and other things available to pass coordinates to that will return the elevation data. I was just hoping to get the info myself from the files - converting it from binary in the process.


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    #4
    Alun
    Registered Users Posts: 21,466 ✭✭✭✭Alun


    It should be a pretty trivial task to write a small program to convert these files into some kind of readable ASCII format if that's what you're after?


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    #5
    WithCheesePlease
    Registered Users Posts: 1,006 ✭✭✭WithCheesePlease


    Alun wrote: »
    It should be a pretty trivial task to write a small program to convert these files into some kind of readable ASCII format if that's what you're after?

    I would have thought so, but back to my original problem of not being able to see into the file to see what I'm trying to convert...


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    #6
    Alun
    Registered Users Posts: 21,466 ✭✭✭✭Alun


    gearoid_healy wrote: »
    I would have thought so, but back to my original problem of not being able to see into the file to see what I'm trying to convert...
    I'm not sure I understand what you're trying to achieve. It's just a binary file, a bunch of numbers representing elevation at points on a matrix, nothing to see really. As long as you know the format the file is in, you can write your application based on that knowledge. If you're that interested, just use any old hex viewer or editor, or as I said write a 5 line program to convert it to ASCII first and view it with notepad.


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