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
