Nicolas, Tried it once again, short names and reasonable paths do not work. I am on Mac, QGIS 3.24, will test some reasons for the failure tomorrow again and report. Thanks for your advice,
Maria > Am 30.03.2022 um 09:34 schrieb Nicolas Cadieux via Qgis-user > <[email protected]>: > > Hi, > > "Polygonize" should work well to vectorize the raster classes. If you have > problems with the file name, try simplifying the file name to the bare > minimun like c:\temp\toto.shp if you're on Windows. Make sure you have no > spaces or accents in the path (this includes the user path of your operation > system). Notice that there are two polygonize algorithm. One is from QGIS > and one is from GDAL. Try both. They are probably both based on GDAL but > one (probably the QGIS one) may have an easier time with accents, spaces or > special characters like '\n'. > > Good luck > > Nicolas > > On 2022-03-29 7:51 p.m., Shinoto, PD Dr. Maria via Qgis-user wrote: >> Hi Kirk, >> >> that was helpful, thank you. >> >> I am not yet where I need to be, but so far I could create two classes with >> the formula found in the docs >> (https://docs.qgis.org/3.10/en/docs/user_manual/working_with_raster/raster_analysis.html) >> along this line: >> >> `("slope@1" < 50) * 1 + ("slope@1" >= 50) * 2` >> >> At this moment, my biggest problem is creating the vector file, the window >> claims that the file name is too long. This cannot be the case, and the >> directory itself should be OK. So now I am trying to get this done, and then >> I will test three classes, which I did not get working up to now either. >> >> If there are easy answers to these two questions, I would be pleased, >> otherwise, I will try tomorrow. >> >> Thanks a lot, >> Maria >> >> >> >>> Am 30.03.2022 um 07:14 schrieb kirk <[email protected]>: >>> >>> Hi Maria. >>> The symbology does not reclassify the underlying raster, it just changes >>> the way it is displayed. Use the raster calculator to generate a new >>> raster with the Classes you require. The native qgis calculator works well. >>> You can find it in the upper word menu under raster. Once you have your >>> raster reclassified, you can then convert it to a vector format >>> >>> Kirk Schmidt >>> >>> >>> >>> Sent from my Galaxy >>> >>> >>> -------- Original message -------- >>> From: "Shinoto, PD Dr. Maria via Qgis-user" <[email protected]> >>> Date: 2022-03-29 6:32 p.m. (GMT-04:00) >>> To: qgis forum <[email protected]> >>> Subject: [Qgis-user] creating vector layer from slope map with few classes >>> >>> Hi, >>> >>> I have created a slope map from a DTM. >>> >>> I have limited the symbology to three meaningful classes and wish to create >>> a vector layer with polygons of three classes from that. The conditions are >>> One-Channel-Pseudocolor, Channel1 (Gray), interpolation discrete, modus >>> "fortlaufend" -- not identical interval or quantile, 3 classes with values >>> <=20, 20 - 40, > 40. >>> >>> The classes show up in the layer design panel symbology tab, but the layer >>> browser still (thankfully!) shows the greyscale ramp. >>> >>> I wish to create a vector layer with polygons from the 3 classes. >>> >>> All solutions I have looked up work under slightly different condition. >>> After all I do not know how to get the data of the DTM into three classes >>> like "Flat-Gentle-Steep"; I think the vectorization should work easily then. >>> >>> Can anybody hint me to a solution? >>> >>> >>> Thanks and best wishes, >>> Maria >>> _______________________________________________ >>> Qgis-user mailing list >>> [email protected] >>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >>> >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > -- > Nicolas Cadieux > https://gitlab.com/njacadieux > > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user _______________________________________________ Qgis-user mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
