<div dir="ltr">Could it also be the resampling of the image and or an issue with the PNG format? I would try tiled geotiffs.<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Jun 12, 2014 at 5:47 PM, Lime, Steve D (MNIT) <span dir="ltr"><<a href="mailto:Steve.Lime@state.mn.us" target="_blank">Steve.Lime@state.mn.us</a>></span> wrote:<br>
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<p class="MsoNormal"><span style="color:#1f497d">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?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">Steve<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:mapserver-users-bounces@lists.osgeo.org" target="_blank">mapserver-users-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:mapserver-users-bounces@lists.osgeo.org" target="_blank">mapserver-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Lars I. Nielsen<br>
<b>Sent:</b> Thursday, June 12, 2014 9:02 AM<br>
<b>To:</b> <a href="mailto:mapserver-users@lists.osgeo.org" target="_blank">mapserver-users@lists.osgeo.org</a><br>
<b>Subject:</b> [mapserver-users] TileIndex - accuracy and truncation ?<u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Hi,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">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.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Howeever, white lines appear between some of the tile rows (not all) at some scales (not all).<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">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.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Tiles are 2254 pixels high, and (as per the WLDs below) 6138899.3169212583 - 0.0204375000 * 2254 = 6138853.2507962583 (almost equal to 6138853.2507962584)<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Which leads me to suspect that some sort of truncation goes on, yielding some sort of rounding error.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Do anyone know whether the tileindex calculations truncates any of the values in the WLD files ? And if so, by how much ?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Cheers.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">--<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">A typical map picture with a white line can be seen via this link:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><a href="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" target="_blank">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</a><u></u><u></u></p>
<p class="MsoNormal">Here's the WLD of the two tiles displayed in the picture:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Upper tile WLD:<u></u><u></u></p>
<p class="MsoNormal">0.0204375000<u></u><u></u></p>
<p class="MsoNormal">0.0000000000<u></u><u></u></p>
<p class="MsoNormal">0.0000000000<u></u><u></u></p>
<p class="MsoNormal">-0.0204375000<u></u><u></u></p>
<p class="MsoNormal">586620.6934394070<u></u><u></u></p>
<p class="MsoNormal">6138899.<a href="tel:3169212583" value="+13169212583" target="_blank">3169212583</a><u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Lower tile WLD:<u></u><u></u></p>
<p class="MsoNormal">0.0204375000<u></u><u></u></p>
<p class="MsoNormal">0.0000000000<u></u><u></u></p>
<p class="MsoNormal">0.0000000000<u></u><u></u></p>
<p class="MsoNormal">-0.0204375000<u></u><u></u></p>
<p class="MsoNormal">586620.6934394070<u></u><u></u></p>
<p class="MsoNormal">6138853.<a href="tel:2507962584" value="+12507962584" target="_blank">2507962584</a><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">--<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">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.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">Kind regards / Med venlig hilsen<br>
Lars I. Nielsen<br>
----------------------------------------------------------------<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d" lang="DA">Landinspektør, Senior GIS Programmør og Konsulent<br>
Hvenegaard Landinspektører A/S<br>
Rugaardsvej 55, DK-5000 Odense C<br>
Denmark<br>
Tel. <a href="tel:%2B45%206313%205050" value="+4563135050" target="_blank">+45 6313 5050</a><br>
<a href="http://www.hvenegaard.dk/" target="_blank">http://www.hvenegaard.dk</a><u></u><u></u></span></p>
<p class="MsoNormal"><span lang="DA"><u></u> <u></u></span></p>
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