Thanks for the tip. Also importand is to add -addalpha otherwise it will not work. The RGB code for transparent is "255 255 255". And here the complete terminal input: gdalbuildvrt -addalpha -srcnodata "255 255 255" -vrtnodata "255 255 255" WK182.vrt *.tif
Thanks for your help Thomas Am Dienstag, den 23.06.2015, 22:11 +0200 schrieb Kay F. Jahnke: > Am 23.06.2015 um 20:45 schrieb Baur, Thomas: > > Hello > > > > I have scanned a paper map in several A3 pieces, cut the edges with gimp > > and referenced them with the qlandkartegt georeferencing tool. > > Combining the single referenced maps in a map collection (qmap) I get > > one complete nice looking map where all single tiles fit perfect > > together. Also I can work with the several zoom levels. > > > > If I take the georeferenced tiles and prepare a vrt file for use in > > QMapshack, I have big gaps in the resulting map (please see attached > > picture). For proceeding the vrt file I use QMapShak VRT builder. Also > > zoom levels are not working. > > This doesn't look like gaps to me, but like sections of the tiles which > have no data and cover other data. This is a result of transforming the > original images to another projection: the new image is rectangular, but > the transformed data aren't anymore, after the transformation. Usually > you have to tell the VTR builder to use a specific no-data value; If the > VRT builder knows that, it can avoid displaying parts with no data, if > it doesn't, it just takes these areas as part of the data, resulting in > the artifacts you observe. > > In gdalbuildvrt, the relevant parameters are > > [-srcnodata "value [value...]"] [-vrtnodata "value [value...]"] > > The first one declares the no-data value for your input, the second for > your output. > > > Are there any special terminal commands to get one nice looking map from > > the singe tiles? > > Try and use gdalbuildvrt on the command line with the approporiate > no-data values. In my version of qmapshack I can't see any options for > the no-data value, so I suppose it uses defaults which don't work in > your case. > > An alternative to working with several tiles is to stitch the individual > scan pages into one image and use that instead of the VRT. I use hugin > for the purpose: Optimize only for roll, TrX and TrY (maybe g and h, > depending on your scanner, but go slow on the number of parameters at > first and make sure you have plenty of control points). > > Kay > > > ------------------------------------------------------------------------------ > Monitor 25 network devices or servers for free with OpManager! > OpManager is web-based network management software that monitors > network devices and physical & virtual servers, alerts via email & sms > for fault. Monitor 25 devices for free with no restriction. Download now > http://ad.doubleclick.net/ddm/clk/292181274;119417398;o > _______________________________________________ > Qlandkartegt-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/qlandkartegt-users ------------------------------------------------------------------------------ Monitor 25 network devices or servers for free with OpManager! OpManager is web-based network management software that monitors network devices and physical & virtual servers, alerts via email & sms for fault. Monitor 25 devices for free with no restriction. Download now http://ad.doubleclick.net/ddm/clk/292181274;119417398;o _______________________________________________ Qlandkartegt-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/qlandkartegt-users
