I forgot to add that I do know the scale of the map in the image - meaning I do know the size of each pixel. However, I do not know if that size is constant as I move right or move down, but from what I have read, it seems like the scale just varies over the map based on the projection, so knowing the scale at the starting point, I am thinking, I should be able to find the scale as I move right to another point, or move down to another point.
Adrian Custer wrote: > > Hello, > > Your problem, as you state it, is unfortunately not solvable. (Ha! My > favourite answer in math class: "this problem is impossible"). > > A simple way for you to see this lack of completeness is to make the > thought experiment where you would "cut the outer 50 pixels all around > your image" to make imageB. To calculate the coordinates of the top left > corner of this imageB, you could re-use *all* the info you give us in > your "I have" section. But since nothing has changed between your > original problem and the problem with imageB, you can see that something > is amiss; if you could solve either problem, you could solve both and > you would get the same answer. This is clearly non-sensical; actually > you can't solve either problem because your setup is under-determined > meaning you need more information to solve your issue. > > To approach things the way you are approaching them you would need to > know also (1) the size of each pixel and (2) the number of pixels. > Unfortunately, the ground size of the pixels will not be fixed so you > could not really proceed in the way you have constructed your problem > without a lot of complex math and much more data. > > So you need to really look at what other information you can generate > and set up your problem so you can solve it. Alternatively, you may > decide you can't solve your problem but you can fake it by > rubber-sheeting or some other approximation method. If this is a single > time problem, you might be able to fire up uDig with the experimental > rubber-sheeting plugin to get your image "in the right place". > > good luck, > adrian > > > > On Fri, 2007-11-02 at 20:51 -0700, mzorova wrote: >> Hello, >> >> I am completely new to GIS and have a project that requires some GIS >> functionality and I have spent the last week (in vain) trying to do it >> from >> first principles, learn how I might use geotools2 from the geotools wiki >> and >> the javadocs, and I have to say I am more confused than when I started, >> though I have learnt of the existence of a lot of concepts, I don't quite >> grasp how they might be used to help me solve the problem at hand. >> >> My problem is as follows: >> >> I have: >> + an map image in PNG format >> + the latitude and longitude of the CENTER of the above map >> + the projection of the above map (plate carree) >> + the datum used for the above map (NAD83) >> >> I need: >> + the latitude and longitude of the top left and bottom right corners of >> the >> map >> + the latitude and longitude of the point that is <width-of-map-image> >> pixels to the right of the center of map >> + the latitude and longitude of the point that is <height-of-map-image> >> pixels to the bottom of the center of the map >> >> Unfortunately, after all the reading and searching, I am completely lost >> and >> really do not even know where to start looking. >> >> A small snippet of Geotools2 code that does something like the above >> would >> be incredibly useful in pointing me towards the right modules of the >> geotools codebase where I can dig deeper. I know that has probably >> something >> to do with the referencing module, but I have NO idea what the code needs >> to >> look like to get started. >> >> Any help at all would be GREATLY appreciated. Thanks so much in advance >> for >> your patience with a newbie query. >> >> >> > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > _______________________________________________ > Geotools-gt2-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users > > -- View this message in context: http://www.nabble.com/Newbie-question---completely-lost-tf4741832.html#a13563664 Sent from the geotools-gt2-users mailing list archive at Nabble.com. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Geotools-gt2-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
