[Mapserver-users] MapServer raster 'cracking' problem

[Richard Greenwood]

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I have run into this occasionally in mapserver and frequently in MapInfo. I 
put a fair amount of overlap into adjacent tiles; 10 to 100 pixels.

Rich

At 07:21 AM 11/9/2003, you wrote:

>I reproduced the problem with only two tiles.
>It was east to verify using gdalinfo that the two tiles are adjacent along
>the problematic border.
>Indeed it sounds like a problem with rounding.
>to reduce the amount of code to check, I can tell you that its probably not
>related to the driver of the specific format, because I reproduced it both
>with ECW and with GeoTiff (and the problem looks exactly the same, given the
>same data and map bounds).
>For me, it's not urgent yet, but I would be happy to know this problem is
>history, because I currently have a solution which relies on MapServer.
>
>         Omry.
>
>
>-----Original Message-----
>From: Ed McNierney [mailto:ed at topozone.com]
>Sent: Sunday, November 09, 2003 3:09 PM
>To: Omry Yadan; Alan Steremberg
>Cc: mapserver-users at lists.gis.umn.edu
>Subject: RE: [Mapserver-users] MapServer raster 'cracking' problem
>
>Omry -
>
>I don't have time to look into this for a few more days, but I suspect
>you are seeing an artifact of your data and rounding effects.  First,
>make sure your data are as truly continuous as possible.  I think what
>you're seeing is a request for a pixel that falls "between" your data
>sets, or at least appears to fall between them for certain view scales.
>
>         - Ed
>
>
>Ed McNierney
>President and Chief Mapmaker
>TopoZone.com
>ed at topozone.com
>
>
>-----Original Message-----
>From: Omry Yadan [mailto:omry at telmap.com]
>Sent: Sunday, November 09, 2003 3:56 AM
>To: Alan Steremberg
>Cc: mapserver-users at lists.gis.umn.edu
>Subject: RE: [Mapserver-users] MapServer raster 'cracking' problem
>
>
>This seems to be a real problem with MapServer.
>Is anyone taking a look at it?
>
>-----Original Message-----
>From: Alan Steremberg [mailto:alans at wunderground.com]
>Sent: Wednesday, November 05, 2003 7:36 PM
>To: Omry Yadan
>Cc: mapserver-users at lists.gis.umn.edu
>Subject: Re: [Mapserver-users] MapServer raster 'cracking' problem
>
>
>I see the same problem using JPG or PNM files with GDAL.
>
>Alan
>
>----------------------------
>  Alan Steremberg
>  415-543-5021 x 103
>  http://www.wunderground.com
>
>On Wed, 5 Nov 2003, Omry Yadan wrote:
>
> > I have a problem with raster image generated by map server where the
>data
> > source is tiled.
> > The problem is that in some zoom levels (zoomed out), I get a white
>line
> > between two tiles sometimes.
> > I ran a test with two tiles only, and I could reproduce the problem.
> > the tiles boundaries are exactly one next to the other - to strengthen
>the
> > point :
> > when I zoom into the merge line, I don't see a gap between the two
>tiles.
> > Initially, my data was in ECW format - to rule out ECW related issue,
>I
> > converted the data to GeoTiff, and I got the exact same problem (which
> > appeared at the exact same requests.
> >
> > Any help would be appreciated.
> >
> >       Omry.
> >
> > _______________________________________________
> > Mapserver-users mailing list
> > Mapserver-users at lists.gis.umn.edu
> > http://lists.gis.umn.edu/mailman/listinfo/mapserver-users
> >
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Richard W. Greenwood, PLS
Greenwood Mapping, Inc.
Rich <at> GreenwoodMap <dot> com
(307) 733-0203
http://www.GreenwoodMap.com 

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