Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'v got a detail map for an event as PDF an made an openlayers slippy map with Maptiler. I now need to place markers at the position of gps/gsm-trackers, which store their coordinate on a server.

The map's north isn't at top and i need some kind of formula (projection?) to translate the gps coordinates to the coordinates of my map.

Is this somehow possible, e.g. via. 2 points where I know the coordinates in both systems?

I don't expect a finished solution but maybe you can give a hint where to start, I've no idea how to do this.

Example: GPS 48.26771, 16.36882 (somewhere in Vienna, Austria) in my projection is 0, 0

GPS 48.26673, 16.3696 is 100, 0

share|improve this question
For starters, can you provide an example of your coordinates, which projection are they in currently, and which projectio do you wish them to be in after conversion? – CatchingMonkey Jun 13 '12 at 8:53
edited my question, please see example above – stwagner Jun 13 '12 at 9:15

The general approach is to georeference the image/PDF, perform a reprojection if necessary (will screw up labels though!) and only then create tiles and overlays.

For georeferencing, you can use QGIS georeferencer for example.

share|improve this answer
thanks for the idea, but everything is based on the coordinate system starting with 0,0 on the left top. isn't it possible to translate the coordinates? – stwagner Jun 13 '12 at 12:21
Depending on how the PDF map looks like it might be possible to find working transformation settings for scaling, translating and rotating. You can read up on the theory e.g. at…. – underdark Jun 14 '12 at 6:42

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.