Could it also be the resampling of the image and or an issue with the PNG format? I would try tiled geotiffs.
On Thu, Jun 12, 2014 at 5:47 PM, Lime, Steve D (MNIT) < steve.l...@state.mn.us> wrote: > The world files are read internally by GDAL, not MapServer. I wonder if > there’s a way to test this just using GDAL and take MapServer out of the > equation completely. Is there any projection being done? That could also be > a source of slivers. Is it possible to generate the tiles with just a bit > of overlap? > > > > Steve > > > > *From:* mapserver-users-boun...@lists.osgeo.org [mailto: > mapserver-users-boun...@lists.osgeo.org] *On Behalf Of *Lars I. Nielsen > *Sent:* Thursday, June 12, 2014 9:02 AM > *To:* mapserver-users@lists.osgeo.org > *Subject:* [mapserver-users] TileIndex - accuracy and truncation ? > > > > Hi, > > > > For performance reasons, I've (used FME to) split a large PNG into 450 > small tiles, serving them with a Mapserver tileindex as a WMS service to a > web solution. > > > > Howeever, white lines appear between some of the tile rows (not all) at > some scales (not all). > > > > I've looked deeper into the WLD files for the individual tiles, and found > that the calculations are accurate to 1/10 of a nanometer. At least if one > uses all 10 decimals. > > > > Tiles are 2254 pixels high, and (as per the WLDs below) 6138899.3169212583 > - 0.0204375000 * 2254 = 6138853.2507962583 (almost equal to > 6138853.2507962584) > > > > Which leads me to suspect that some sort of truncation goes on, yielding > some sort of rounding error. > > > > Do anyone know whether the tileindex calculations truncates any of the > values in the WLD files ? And if so, by how much ? > > > > Cheers. > > > > -- > > > > A typical map picture with a white line can be seen via this link: > > > > > http://hvmgo01.hvenegaard.dk/mswms/mapserv.exe?map=odensekkgd_wms.map&LAYERS=ASSISTENS&TRANSPARENT=true&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&FORMAT=image/png&SRS=epsg:25832&BBOX=586609.80952408,6138781.1015875,586686.0222225,6138857.3142859&WIDTH=256&HEIGHT=256 > > Here's the WLD of the two tiles displayed in the picture: > > > > Upper tile WLD: > > 0.0204375000 > > 0.0000000000 > > 0.0000000000 > > -0.0204375000 > > 586620.6934394070 > > 6138899.3169212583 > > > > Lower tile WLD: > > 0.0204375000 > > 0.0000000000 > > 0.0000000000 > > -0.0204375000 > > 586620.6934394070 > > 6138853.2507962584 > > > > -- > > > > Ps! As I wrote previously, I'm using FME to create the tiles. So I have > little control over the actual coordinate and pixel values, and only > specify the number of tiles I need. So manual truncation is not really a > viable option. > > > > > > Kind regards / Med venlig hilsen > Lars I. Nielsen > ---------------------------------------------------------------- > > Landinspektør, Senior GIS Programmør og Konsulent > Hvenegaard Landinspektører A/S > Rugaardsvej 55, DK-5000 Odense C > Denmark > Tel. +45 6313 5050 > http://www.hvenegaard.dk > > > > _______________________________________________ > mapserver-users mailing list > mapserver-users@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/mapserver-users > -- *Travis Kirstine* *First Base Solutions I**nc*. tkirst...@firstbasesolutions.com 140 Renfrew Dr. | Suite 100 | Markham, ON | L3R 6B3 p. 905-477-3600 ext. 301 | m. 647-534-4798 http://www.firstbasesolutions.com
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