[mapguide-trac] #91: Images returned by raster queries may be the wrong size

[MapGuide Open Source]

#91: Images returned by raster queries may be the wrong size
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   Reporter:  traianstanev     |       Owner:  traianstanev
       Type:  defect           |      Status:  new         
   Priority:  medium           |   Milestone:  1.2         
  Component:  Mapping Service  |     Version:  1.2.0       
   Severity:  minor            |    Keywords:              
External_id:  923590.01        |  
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 When using the RESAMPLE command to query for a raster, Mapguide relies on
 RESAMPLE returning a scaled raster of the correct size.

 The arguments to RESAMPLE specify the viewport that the user is currently
 viewing. Suppose the viewport covers the box (0,0 200,100) in mapping
 space and the viewer is 2000x1000 pixels. These are all arguments to
 RESAMPLE. Suppose we have a raster that covers the bounds (50,50 60,60) in
 mapping space. This is a 10x10 unit region and it corresponds to a region
 on the screen that is 100x100 pixels. Instead of returning a 100x100
 raster, we get a 2000x1000 raster from the raster provider. It looks ok
 since it gets scaled by the renderer to cover the correct spot, but the
 overhead becomes huge if one is zoomed out and is looking at an overview
 of say 100 rasters.

 In order to work around this MapGuide can explicitly set the size it wants
 the raster to be, after completing the raster FDO query and getting more
 information about the raster back, but before getting the actual byte
 stream for the raster.

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Ticket URL: <http://trac.osgeo.org/mapguide/ticket/91>
MapGuide Open Source <http://mapguide.osgeo.org/>
MapGuide Open Source Internals