<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hello Jochem,<div class=""><br class=""></div><div class="">As one mentioned, and i know it’s not answering your question.</div><div class="">But what kind of data (and sensor) did you have/used to reach this accuracy?</div><div class="">And how do you calculate this accuracy, what reference data did you used?</div><div class=""><br class=""></div><div class=""><div class="">Thanks for enlightening me.</div><div class="">Best regards</div><div class="">Antoine</div><div class=""><div class="">
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<br class=""><div><blockquote type="cite" class=""><div class="">On 23 Mar 2017, at 09:21, Jochem <<a href="mailto:jochem.lesparre@kadaster.nl" class="">jochem.lesparre@kadaster.nl</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Hi Kristian,<br class=""><br class="">I can not show that cs2cs makes an approximation error by using only cs2cs.<br class="">I have to compare it with other software. But what transformation software<br class="">is available to you that would you trust more than Proj.4? The best way to<br class="">show it, is to compute a transformation in computational software like<br class="">Matlab twice. One time with the approximate formulas, giving the same result<br class="">as cs2cs, and one time with the strict formulas, giving a 4 cm different<br class="">result. As not everyone here will have Matlab, I am thinking of using Excel.<br class="">Do you think that is a good idea?<br class=""><br class="">Thanks for the information on how to use a development version of PROJ.4<br class="">with QGIS. This sounds complicated. Maybe I would manage to do it with a lot<br class="">of effort and some help. But I am afraid I can't expect the government<br class="">agency here to reproduce that.<br class=""><br class="">In the Netherlands, the official transformation RDNAPTRANS will probably be<br class="">updated this year in a way that it can be done with Proj.4. I hoped to be<br class="">able to do the same here, but the approximation error is preventing me from<br class="">doing so.<br class=""><br class="">Regards, Jochem<br class=""><br class=""><br class=""><br class="">--<br class="">View this message in context: <a href="http://osgeo-org.1560.x6.nabble.com/towgs84-approximation-error-tp5313738p5313821.html" class="">http://osgeo-org.1560.x6.nabble.com/towgs84-approximation-error-tp5313738p5313821.html</a><br class="">Sent from the PROJ.4 mailing list archive at <a href="http://nabble.com" class="">Nabble.com</a>.<br class="">_______________________________________________<br class="">Proj mailing list<br class=""><a href="mailto:Proj@lists.maptools.org" class="">Proj@lists.maptools.org</a><br class="">http://lists.maptools.org/mailman/listinfo/proj<br class=""></div></div></blockquote></div><br class=""></div></div></body></html>