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'm unable to find out a formula for converting 3tm coordinates to lat-lon? 3tm is a system used in Alberta alone, as far as I can tell. The city of Calgary uses that for its opendata, which is what I'm trying to process.

share|improve this question
up vote 2 down vote accepted

gdaltransform will work, I must've just missed you on irc. I assume that 3tm is the projection here:

to convert to WGS84 longitude/latitude:

gdaltransform -s_srs epsg:3776 -t_srs epsg:4326

Then type in your coordinates.

share|improve this answer

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.