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I've heard it is possible to use NASA elevation model to determine approximate elevation at (lat;lng) point. This might be really useful for my upcoming project since Google Elevation API has weird limitations...and I don't really like USGS Elevation Query Web Service because of its speed. I'd want to have elevation query tool/framework on local computer, which works with local file.

I did my homework, and found GeoTiff files might be downloaded with no problem. But I've failed to find any useful documentation or framework.

Can somebody share a link to the specs, or example or tutorial on how to work with GeoTiff files? Is there any frameworks to get this done (.NET,Java,C++,C - doesn't really matter)?

According to what I see in the GeoTiff files and its header files, I assume each tiff represents small area and pixel color (16 bit value) indicates elevation there in meters. Is that correct?

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I didn't know there's a GIS section. How do I move my question there? –  Alex D Dec 30 '11 at 15:38
    
Interesting question, but voting to close and move to GIS. –  Perception Dec 30 '11 at 15:59
    
@AlexD Since it's not one of the most common alternate topics, I think a moderator has to do it. I have flagged the question to get the moderators' assessment. –  erickson Dec 30 '11 at 16:18
    
@erickson Thanks! meanwhile, I've found framework in C#, which pretends it can handle GeoTiffs. –  Alex D Dec 30 '11 at 18:48
    
I am not sure which Tiff's you're talking about and what resolution you need but ASTER GDEM seems to be most detailed DEM for FREE :) Check gis.stackexchange.com/questions/17989/…. ASTER is 30m. SRTM is 90m. –  Tomek Jan 2 '12 at 20:41
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migrated from stackoverflow.com Jan 2 '12 at 12:39

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2 Answers

If you're referring to NASA's SRTM dataset, there is an alternative to GeoTIFF file format - you can download HGT files, which are simpler to decode (see the Quickstart PDF and the rest of the SRTM documentation).

You can also check out my answer to a similar question: How to get an elevation profile for a gps track?

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thanks! your answer is really helpful! –  Alex D Jan 3 '12 at 9:14
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digging deep enough I've found framework that can handle GeoTiff files . it is http://www.gdal.org/ I didnt try to use this whole framework, but it has a lot of source code that explains how to use geo data, geo algorithms and standards. I was even able to build my simple app which works perfect for me so far. That's a win!

This framework answers my original question. I can see how to handle and convert GeoTiff files and implement my own light-weight "engine" that fit my needs.

digging even deeper, check out http://freegis.org/database/?cat=1 there's a lot of frameworks, data sets and geo tools listed there. This website might be a good start point if you're working on any kind of geo (geo dependent) project.

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