[mapguide-users] Erratic display of feature labels

[Traian Stanev]

This is caused by, how can I say it, impefections, in the label
occlusion avoidance algorithm. The problems happen especially when text
is rotated, in which case the bounding box used to compute the region
covered by the label is no longer tight. This, combined with the fact as
new features appear on the map, the order labels get processed changes,
causes the behavior you describe. So it is currently normal for some
labels to disappear and appear depending on the view. One solution I
could offer is to turn off label overpost detection for the layer --
there is a checkbox for that in Studio, in the style dialog -- this
would cause all labels to draw. Another solution would be to use a tiled
map, which would result in a more fixed labeling, but then some labels
may just never show up. A third solution may be to use a smaller font so
that more labels fit. A fourth solution is for us to improve the
labeling to deal with non-axis-aligned bounds. :-)
 
 
Traian
 

  _____  

From: Jackie Ng [mailto:jackie.ng at aecsystems.com.au] 
Sent: Tuesday, October 10, 2006 4:30 AM
To: users at mapguide.osgeo.org
Subject: [mapguide-users] Erratic display of feature labels


Hi All,
 
I am experiencing a very strange problem with the display of feature
labels. Basically the map is only showing a subset of all the feature
labels that are actually there. At closer zoom levels, when I am panning
around on my map, some labels will magically disappear while some will
magically appear. The attached images will better explain the problem. 
 
The "before" image a partcular close-up view of the map. 
The "after" image is the same view, panned slightly to the right. 
The "after-more" image is the "after" view panned slightly up.
 
The selected polygon in blue is the same polygon for all 3 images.
 
Notice how some labels disappear and some appear during these
transitions? 
 
Help me :(

Regards,

Jackie Ng

AEC Spatial Pty Ltd. / AEC Systems Pty Ltd.
SYDNEY - MELBOURNE - BRISBANE - PERTH - ADELAIDE - HOBART 

A.B.N: 32 075 809 451

Level 4, 37-41 Prospect St. Box Hill, Victoria, 3128

Phone: 1300 368 609 
Fax:    1300 362 140 

www.aecsystems.com.au 
jackie.ng at aecsystems.com.au

 
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