[mapguide-users] ScreenToMapUnits problems

[George McLean]

I am guessing the problem is not factoring in the width of the layers frame.

Any thoughts or hints using ScreenToMapUnits would still be appreciated.

Thanks

George McLean


George McLean wrote:
> Hello,
>
> I am experimenting with the ScreenToMapUnits(x,y) function in php with 
> Apache on windows XP. I am capturing the screen coordinates of a mouse 
> click with javascript and attempting to convert to map coordinates 
> with ScreenToMapUnits. When I compare the results of ScreenToMapUnits 
> with the coordinates in the status bar, the Y coordinate looks really 
> accurate while the X coordinate is off. The amount X is off depends on 
> the zoom level. The farther out I am zoomed the worse it is. My 
> coordinate system is Wisconsin South State Plane Grid South NAD83 
> (WI83-SF). At a zoom level where the map displayed is roughly 3 miles 
> wide the error is about 2000'.
>
> I am not sure if there is some problem in the capture of the screen 
> coordinates or some other issue with the coordinate system. Has anyone 
> seen this sort of problem or does anyone have any suggestions on how 
> to troubleshoot this? How accurate should I expect ScreenToMapUnits to 
> be?
>
> Thanks
>
> George McLean
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