[mapguide-users] Precision problem viewing map

[Chris Claydon]

I tried digitizing a rectangle, and the result was that it was offset only in the y axis. I believe this corresponds to the small space that you have between the top of the map frame and the top of the map itself. I've seen bugs reported about this gap before, but I'm not sure if they've been resolved.

Chris.

-----Original Message-----
From: mapguide-users-bounces at lists.osgeo.org [mailto:mapguide-users-bounces at lists.osgeo.org] On Behalf Of Stefan Dalakov
Sent: Monday, January 12, 2009 4:12 AM
To: MapGuide Users Mail List
Subject: [mapguide-users] Precision problem viewing map

Hi all,
I am facing a strange and unexpected problem regarding precision of map
and coordinates display. I see that my data is not displayed on the
exact place - there is a shift in Y coordinate. I have a raster layer
with bounding rectangle
Xmin=..., Ymin=7070400, Xmax=.... Ymax=7071600. But when I move the
mouse pointer at the lower left corner I see Y=7070320 (at scale 1:2000
let say) or similar value, and the difference depends on the scale. If I
zoom down, the difference changes, and at scales close to 1:50 it is ok.
The situation is similar at the upper right corner. I observe exactly
the same effect with all other layers.
I wouldn't care too much about this - even if there is a shift, all
layers are shifted equally, but when I digitize a polygon it is also
shifted. Imagine I digitize a polygon to follow a feature on the raster
image, coordinates are recorded , the feature is added to data source,
but when it is added, due to this shift it appears not where it has been
digitized, but shifted.
I guess you did not understand anything of this, but you can visit

http://www.bgmapguide.com:8008/mapguide/rakvag/main.php

click on "draw a new suggestion" and try to digitize 2 adjacent polygons
- you will see them overlap
Please be gentle to the server - it is an old tired horse.
And to save some time - all layers and the map are in the same
coordinate system.
This effect is not depending on the browser (tested with FFox 2 & 3,
Safari and IE) and is not depending on the screen resolution


Best regards : Stefan Dalakov
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