<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr">Hello Dave,</div><div dir="ltr"><br></div><div dir="ltr">I am not very familiar with the grass tools and its error messages. But as an alternative you could use gdal_contour to generate contour lines from a raster layer. </div><div dir="ltr"><br></div><div dir="ltr">Sincerely,</div><div dir="ltr">Christoph</div><div dir="ltr"><br><blockquote type="cite">Am 09.04.2020 um 00:05 schrieb Dave Marshall <43carnaby@gmail.com>:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr">Hello,<div><br></div><div>I've just upgraded to 3.12 from 3.4 and when working with LIDAR data I find that r.contour no longer works. The first warning which occurs is: <span style="color:rgb(255,0,0);white-space:pre-wrap">Datum <Unknown_based_on_Airy_1830_ellipsoid> not recognised by GRASS and no parameters found</span> </div><div>Further error messages are: <span style="color:rgb(255,0,0);white-space:pre-wrap">Datum <Unknown_based_on_Airy_1830_ellipsoid> not recognised by GRASS and no parameters found</span></div><div><span style="color:rgb(255,0,0);white-space:pre-wrap"><br></span></div><div><p style="margin:0px;white-space:pre-wrap"><span style="color:rgb(255,0,0)">WARNING: Unable to open vector map <output4a2f59f8cf014c4d8b8b782e7d15854a@PERMANENT> on level 2. Try to rebuild vector topology with v.build.</span></p>
<p style="margin:0px;white-space:pre-wrap"><span style="color:rgb(255,0,0)">ERROR: Unable to open vector map <output4a2f59f8cf014c4d8b8b782e7d15854a></span></p><p style="margin:0px;white-space:pre-wrap"><font color="#ff0000"> </font><font color="#000000">and finally a message saying the layers were not correctly generated. </font></p><p style="margin:0px;white-space:pre-wrap"><font color="#000000">This routine worked perfectly in version 3.4.</font></p><p style="margin:0px;white-space:pre-wrap"><font color="#000000"><br></font></p><p style="margin:0px;white-space:pre-wrap"><font color="#000000">Is there a simple fix? I am using OSGB 1936 / British National Grid [EPSG:27700] as CRS.</font></p><p style="margin:0px;white-space:pre-wrap"><font color="#000000"><br></font></p><p style="margin:0px;white-space:pre-wrap"><font color="#000000">Thanks,</font></p><p style="margin:0px;white-space:pre-wrap"><font color="#000000"><br></font></p><p style="margin:0px;white-space:pre-wrap"><font color="#000000">Dave Marshall</font></p></div></div>
<span>_______________________________________________</span><br><span>Qgis-user mailing list</span><br><span>Qgis-user@lists.osgeo.org</span><br><span>List info: https://lists.osgeo.org/mailman/listinfo/qgis-user</span><br><span>Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user</span></div></blockquote></body></html>