[Qgis-user] Spikes in Profile Elevation with adjacent polygons of different heights
Dear list I’m playing with QGIS Elevation Profile When I trace the elevation profile of a polygonal layer, in which there are several adjacent polygons of different heights, at the point where there is a variation in height between one polygon and the adjacent one, the module sometimes generates spikes due to (I think) the evaluation of the heights in two points of almost identical coordinates. For example, if I draw the elevation profile along a segment lying on the X axis (from x=0 to x=10) and passing through two polygons that change elevation (from a height of 100 to a height of 200) at the segment abscissa equal to 5, the output of the elevation module could appear as follows: (distance, elevation) 0,100 1, 100 2, 100 3, 100 4, 100 5.0001,200 5.0002,100 6,200 7,200 8,200 9,200 10,200 In other words, at the point (of abscissa approximately = 5) where there is a change in height (from 100 to 200), a spike occurs where, after showing the new height equal to 200 (ad x=5.0001), the old height equal to 100 (at the next point x=5.0002) is represented. Then, we have the new height of 200 at x=6, and so on. Perhaps, the extremely small difference between the point abscissa of 5.0001, and the point abscissa of 5.0002, is not appreciated by the sorting algorithm (based on the distance from the initial point of the segment), which sees them as two equal points, and, arbitrarily, chooses which one to indicate first. Thanks Regards Luigi ___ QGIS-User mailing list QGIS-User@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] split polygon with lines seems not working correctly
Dear David Thanks for your prompt reply. I understood the need for intersection between lines and polygons. But the polygonal layer I work on can have thousands of polygons, and manually lengthening the lines is not feasible. A procedure would be needed to automate this operation. Or, an alternative method (transforming the line divide layer into polygons, or other procedures that can be implemented automatically, I don't know). Regards -Messaggio originale- Da: Qgis-user Per conto di qgis-user-requ...@lists.osgeo.org Inviato: mercoledì 10 giugno 2020 19:02 A: qgis-user@lists.osgeo.org Oggetto: Qgis-user Digest, Vol 172, Issue 15 Send Qgis-user mailing list submissions to qgis-user@lists.osgeo.org To subscribe or unsubscribe via the World Wide Web, visit https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.osgeo.org%2Fmailman%2Flistinfo%2Fqgis-user&data=02%7C01%7C%7C14f8af4905d04a9baabd08d80d6020a4%7C84df9e7fe9f640afb435%7C1%7C0%7C637274053798286325&sdata=1HM%2FeL6ElSKMxahzf7Vtn40F0WneB0yDOVaSltg9uUE%3D&reserved=0 or, via email, send a message with subject or body 'help' to qgis-user-requ...@lists.osgeo.org You can reach the person managing the list at qgis-user-ow...@lists.osgeo.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Qgis-user digest..." Today's Topics: 1. Re: Cut shapefiles (Richard McDonnell) 2. Re: QGIS mailing lists in NABBLE (Andrea Giudiceandrea) 3. Re: Cut shapefiles (r.cho...@hotmail.com) 4. Re: QGIS mailing lists in NABBLE (Andrea Giudiceandrea) 5. split polygon with lines seems not working correctly (Luigi Raffaele Sapone) 6. Re: split polygon with lines seems not working correctly (David Greenewalt) -- Message: 1 Date: Wed, 10 Jun 2020 08:35:03 + From: Richard McDonnell To: Riccardo D'Alvito , "qgis-user@lists.osgeo.org" Subject: Re: [Qgis-user] Cut shapefiles Message-ID: <3acfb00ccdf0493db4b8e0ea7f197...@opw.ie> Content-Type: text/plain; charset="utf-8" Hi Riccardo, You could try the Split with Lines tool available in the Processing Toolbox, under Vector Overlay. Just use "Split" in the search bar to narrow down the list. Hope this helps, Richard -- Richard McDonnell MSc GIS, FME Certified Professional FRM Data Management -- Oifig na nOibreacha Poibl? Office of Public Works Sr?id Jonathan Swift, Baile ?tha Troim, Co na M?, C15 NX36 Jonathan Swift Street, Trim, Co Meath, C15 NX36 -- M +353 87 688 5964 T +353 1 647 6543 https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.opw.ie%2F&data=02%7C01%7C%7C14f8af4905d04a9baabd08d80d6020a4%7C84df9e7fe9f640afb435%7C1%7C0%7C637274053798296317&sdata=HPMG%2FmndeUl0ZH58kgNn1Sn1NVs14Tvztr1%2FyTi8aow%3D&reserved=0 -- To send me files larger than 30MB, please use the link below https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Ffiletransfer.opw.ie%2Ffiledrop%2Frichard.mcdonnell%40opw.ie&data=02%7C01%7C%7C14f8af4905d04a9baabd08d80d6020a4%7C84df9e7fe9f640afb435%7C1%7C0%7C637274053798296317&sdata=fVXcYitWgdbQF3LchUTNNNW1Q7I9q9UZQ4pgkYb8luQ%3D&reserved=0 Email Disclaimer: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.opw.ie%2Fen%2Fdisclaimer%2F&data=02%7C01%7C%7C14f8af4905d04a9baabd08d80d6020a4%7C84df9e7fe9f640afb435%7C1%7C0%7C637274053798296317&sdata=nUHXN3chTovGpOMBSai7IhywUTLWTCaseq4V0%2FWt%2FGA%3D&reserved=0 From: Qgis-user On Behalf Of Riccardo D'Alvito Sent: 09 June 2020 17:43 To: qgis-user@lists.osgeo.org Subject: [Qgis-user] Cut shapefiles Good evening. I would like to cut a shapefile of areas with respect to a shapefile of lines in order to have a resulting shapefile of areas formed by the contours of the various lines. In other words, "Polygon" has a larger extension than "Lines" . I would like to create another area shape made up of various polygons divided according to the outline of the "Lines" shapefile. I hope I was clear. Thanks -- next part -- An HTML attachment was scrubbed... URL: <https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.osgeo.org%2Fpipermail%2Fqgis-user%2Fattachments%2F20200610%2F523dd577%2Fattachment-0001.html&data=02%7C01%7C%7C14f8af4905d04a9baabd08d80d6020a4%7C84df9e7fe9f640afb435%7C1%7C0%7C637274053798296317&sdata=%2B7aHt%2Fo77IcbqL%2FXAD%2BpgwcyfWU5lbEvl%2BV3ixEKA%2F4%3D&reserved=0> -- Message: 2 Date: Wed, 10 Jun 2020 02:51:27 -0700 (MST) From: Andrea Giudiceandrea To: qgis-user@lists.osgeo.org Subject: Re: [Qgis-user] QGIS mailing lists in NABBLE Message-ID: <1591782687069-0.p...@n6.nabble.com>
[Qgis-user] split polygon with lines seems not working correctly
Hello I'm using QGIS 3.12 I have a poly shapefile named building.shp in the zip file, and a line shapefile, named line.shp. I'm using the geoprocessing function 'split polygon by line' using poly.shp as input, and line.shp as divide layer. I obtain the 'split_by_line.shp'. But, in this splitted file, the polygon was not divided considering all the lines present, but only some of them, as visible in 'split_by_line.shp'. Is there something wrong? Regards <> ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
