As amateur and newbie to GIS: I wanted to superimpose data from OpenStreetMap (roads) onto an image made from tiles downloaded from one of the free satellite earth images sites (zoom earth).

QGIS which is free helped me to transform my image in order for it to correspond to correct lat/lon coordinates using 3 landmarks with known lat/lon coordinates. "transform" is more complex than mere scale/translate: the image needs to be warped onto a known coordinate system which allows for expressing the earth's curvature.

All that using a GUI and a plugin ... maybe another plugin could be written for automating the procedure further. But one needs to interact with the input image in order to identify visually the correspondence points. E.g. you know that a given roundabout in an avenue has so-and-so coordinates. You need to visually identify that roundabout in your image. Nobody can do that for you unless you develop image analysis software to do that for known structures... Maybe there is another way unknown to me but that looks like a challenge.

Once my satellite view of my city was mapped on coordinates, I used Geo::ShapeFile::Shape in order to read the shape of each road (downloaded from OpenStreetMap) as a sequence of lat/lon control points and draw them onto the image using Graphics::Magick. The result was accurate enough for my eyes.

That's my minimal (and amateur) experience (and I hate geodesimetry btw).

In reply to Re: Perl Mapping (GIS) by bliako
in thread Perl Mapping (GIS) by johnfl68

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