Vincent GELLY wrote:
> I have a point coverage in French geographical projection in meters
> (Lambert 2 etendu). I want to create 2 fields called X and Y and fill
> them in with points centroid coordinates in meters.
> For the moment, with MapInfo, I just can fill them in with geographical
> coordinates (eg : -1.2658), not in meters, using centroidX(obj) and
> centroidY(obj) functions.
MapInfo supports the projection you mention.
An easy way to fill in X and Y fields
with values for a particular projection is:
1. Make a new Map window showing any table.
2. Select Options -> Show MapBasic Window from MapInfo's menu.
3. Select Map -> Options, choose the "Projection..." button.
Choose the projection that you want your coordinate values in.
HOWEVER, if the map is already in that projection, choose a
DIFFERENT projection for the map and repeat step 3 to
change it BACK to the projection you want.
4. At this point, MapInfo will have printed a statement
Set Map Coordsys blah...
in the MapBasic window. If you had to change the projection
twice there will be two of them; use the second one.
Using the cursor keys or the mouse, delete the word "map"
from this line (so that it says "Set coordsys blah..."), then hit ENTER.
You have just changed the "current projection" to the projection you want.
5. Since you're already at the keyboard in the MapBasic window,
you might as well do the update from there. Type
Update tab_name set X = CentroidX (obj), y = CentroidY (obj)
where "tab_name" is the name of the table you are updating,
and hit ENTER. Your X and Y fields will be filled with
coordinate values for the current coordinate system, in this
case the one you want.
I suggest you read up on projections in the MapInfo manuals,
it will clear up things a bit.
Hope this helps.
Spencer
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