[Mapserver-users] MapServer raster 'cracking' problem

[Ed McNierney]

Adding OFFSITE does not slow down MapServer rendering; Frank Warmerdam
and I had a little conversation about this a while back, and I did some
further testing.  Pixels with the OFFSITE value were handled marginally
*faster* than other pixels - very marginally faster, but certainly not
slower.

	- Ed


Ed McNierney
President and Chief Mapmaker
TopoZone.com
ed at topozone.com


-----Original Message-----
From: Palanisamy, Giri [mailto:palanisamyg at ornl.gov] 
Sent: Sunday, November 09, 2003 9:54 AM
To: Omry Yadan; Ed McNierney; Alan Steremberg
Cc: mapserver-users at lists.gis.umn.edu
Subject: RE: [Mapserver-users] MapServer raster 'cracking' problem

Hi,

I had the same problem, then I created an OFFSITE layer for black lines
and it worked, but this seems to slow down the mapserver to load images,
especially when I pan the tiled images.

Giri

-----Original Message-----
From: mapserver-users-admin at lists.gis.umn.edu
[mailto:mapserver-users-admin at lists.gis.umn.edu] On Behalf Of Omry Yadan
Sent: Sunday, November 09, 2003 9:22 AM
To: Ed McNierney; Alan Steremberg
Cc: mapserver-users at lists.gis.umn.edu
Subject: RE: [Mapserver-users] MapServer raster 'cracking' problem

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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