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From: Jody G. <jga...@re...> - 2007-07-17 00:09:51
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Hi Jesse - I am working on putting documentation onto the wiki (on and off when I get time) - have a good steady stream of questions is nice; but having people such as yourself to review the wiki pages is even better :-) I don't have an example of reading a GeoTIFF file right now ... I know you use a the GeoTIFF format and end up with a GridCoverage at the end of the day... GridCoverage has an extent (the bounds of the image) and a coordinate reference system (which you will need to figure out what the points mean). Jesse Sightler wrote: > Is there some tutorial somewhere for those of us who are new to this > world of Geo APIs? Ie, something with some nice examples of how one > might go about solving simple problems given some input file (say a > GeoTIFF file, eg)? > > I've been studying the code for a bit, and have slowly learned how to > get around my earlier issues with a NPE (it should really give a nicer > message when the EPSG data isn't available :) ), but I'm completely > new to all of this. > > Do the APIs provide easy ways to do things like the following: > > * Find the pixel position of a given geographical coordinate? > Translate that position based on scaling the image? > This one will be a bit harder - GridCoverage lets you sample the data at a specific point; I think you can figure out the number of rows and columns > > * Find the distance between two pixels within the raster based > upon the geographical data in the underlying geotiff? > You can find some "distance on spheroid" methods that will tell you the distance between two points. > I apologize if these are questions that get asked often. As I said, > I'm a complete newbie and am trying to pick this stuff up from bits > and pieces on the web. The whole terminology is pretty foreign to > me. :) It is hard to get going; especially since all this stuff deals in data terms and could not care less about pixels :-( Jody |