[mapserver-users] Strange coordinates used in GetFeatureInfo request

[Daniel Morissette]

On 12-06-23 11:00 AM, Daniel Morissette wrote:
> I didn't read your whole mail, but short answer is that I suspect you
> are overlooking the fact that in GetFeatureInfo, the X and Y coordinates
> are in pixels within the view of the map (which is 500x500 pixels in
> your example).
>
> So when you write x=0&y=0 that refers to the top-left corner of the map
> view, and not the 0,0 of the SRS coordinate system... which corresponds
> to longitude=-10, and latitude=+10. Actually, the x,y value is
> translated to be the center of the top-left pixel (and not its top-left
> boundary), which explains why you get lon,lat=9.98,9.98 in the query.
>


Please let me reword this last paragraph to make it a little more clear:

When you write X=0&Y=0 in your GetFeatureInfo request that refers to the 
top-left corner of the map view which is located at longitude=-10, and 
latitude=+10, and not to the 0.0,0.0 of the SRS=EPSG:4326 coordinate 
system. Actually, the X,Y value is translated to be the center of the 
top-left pixel (and not its top-left boundary), which explains why you 
get lon,lat=-9.98,9.98 in the query.


-- 
Daniel Morissette
http://www.mapgears.com/
Provider of Professional MapServer Support since 2000