Correcting a table's projection in MapInfo

Question

Occasionally I have a MapInfo TAB file that doesn't match up with others. Presumably this is because MapInfo is interpreting it as a different projection to the one it was saved as. I am also assuming that it is possible to have two TAB files of different projections in the same workspace and have them match up.

As far as I can see the only way to change a tables projection is to save a copy which doesn't seem to help me.

I there a way to switch projections on the fly? Or at least to find out which projection the TAB file thinks it is and which projection MapInfo is interpreting it as? Am I just being thick?

Answer 1

You can also reproject / attribute another projection your Mapinfo datasets with the free and open-source ogr2ogr GDAL utilty :

http://www.gdal.org/ogr2ogr.html

An easy way to obtain that utility is to install Frank Warmerdam's Tools :

http://fwtools.maptools.org/

Answer 2

You can check what the Map windows projection is by going to Map > Map Options and click the Projections button. This will also allow you to change the maps projection.

You can also check the projections of the tables by going to Table > Maintenance > Table Structure. Here you can check the tables projection.

You are correct, to change the tables projection, you need to save a copy and change the projection on the Save dialog.

Answer 3

MapInfo stores the projection information inside the MAP file. If the coordinates are correct, but you have wrong projection stored, it can only be corrected one way: Export the table to MIF format, edit the coordsys inside the MIF and then import the file again. After that MapInfo will take care of reprojecting the data on-the-fly if you want to show it together with datasets with other projections.