[QGIS-Developer] Shapefile not correctly shown in some areas
Hello, To make things short, I have a device which gathers data in the fields (hundreds of data per second), and gets the position through a GPS (every second). Between 2 GPS positions, I triangulate the positions, so the points are aligned. Sometimes, the device "writes" the data so it spends some time doing so, and it does not gather anything, so I have a "hole". Then, to visualize the data, I create a Shapefile, only with Points. In one Shapefile, I had some strange points: points that appear on the map, but are not clickable and disappear when I zoom in too much. I attach the files ; they can be downloaded here, too: https://www.grosfichiers.com/sjNC3yx7Kvi For instance, in the file I join, the position number 1613 and further are problematic. If my viewing area includes the point 1612, I see all the points, well aligned, but I cannot click points 1613 and further. If I zoom in, or if I move the area and the point 1612 is out of the area, I see nothing anymore. The code to generate the Shapefile has a systematic approach: it takes the points one after the other, and writes their position by incrementing the values. So I suspect there is no bug. In a previous test, the same problem occured BEFORE point 1217 : I could only see the first points if the area included point 1217. Questions: - can anyone try to see my shapefile and confirm the problem? - does this bug ring a bell to anyone? - what may be the problem? Thank you very much! My versions are detailled below. I just updated to the LTR to try to solve the problem, but the bug exists with the 3.22.7-Białowieża and 3.28.14-Firenze versions. Aurélie Version de QGIS 3.28.14-Firenze Révision du code b09131c512 Version de Qt 5.15.3 Version de Python 3.9.5 Version de GDAL/OGR 3.8.2 Version de Proj 9.3.1 Version de la base de données du registre EPSG v10.098 (2023-11-24) Version de GEOS 3.12.1-CAPI-1.18.1 Version de SQLite 3.41.1 Version de PDAL 2.6.0 Version du client PostgreSQL unknown Version de SpatiaLite 5.1.0 Version de QWT 6.1.6 Version de QScintilla2 2.13.4 Version de l'OS Windows 10 Version 2009 Extensions Python actives QGeoloGIS 1.9.0 db_manager 0.1.20 grassprovider 2.12.99 MetaSearch 0.3.6 processing 2.12.99 sagaprovider 2.12.99 === Previously = Version de QGIS 3.22.7-Białowieża Révision du code 5a65627a Version de Qt 5.15.3 Version de Python 3.9.5 Version de GDAL/OGR 3.4.3 Version de Proj 9.0.0 Version de la base de données du registre EPSG v10.054 (2022-02-13) Version de GEOS 3.10.2-CAPI-1.16.0 Version de SQLite 3.38.1 Version de PDAL 2.3.0 Version du client PostgreSQL 13.0 Version de SpatiaLite 5.0.1 Version de QWT 6.1.6 Version de QScintilla2 2.13.1 Version de l'OS Windows 10 Version 2009 20240110-153600.prj Description: Binary data 20240110-153600.cpg Description: Binary data 20240110-153600.shp Description: Binary data 20240110-153600.shx Description: Binary data ___ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [QGIS-Developer] Shapefile not correctly shown in some areas
Thanks a lot Andrea, you found the reason! The extent was wrong, and if I calculate & write it correctly, the file works. (Basically, I calculated it on the GPS points themselves, and not on the interpolated points, and it makes a difference because I interpolate points "before any GPS info" or "after the last GPS point"). To answer to other suggestions: - indeed, writing the file again from QGIS saves the new file in the right format - the .dbf file was not fautly. I had the same symptoms with or without it, so I did not mention it / send it. - I write the shapefiles "by hand", using the ESRI norm, playing around with the Little Endian and Big Endian formats (why did they make it so complex?). Thanks again ! Aurélie - Mail original - De: "Andrea Giudiceandrea via QGIS-Developer" À: qgis-developer@lists.osgeo.org Envoyé: Samedi 13 Janvier 2024 11:47:33 Objet: Re: [QGIS-Developer] Shapefile not correctly shown in some areas Hi all, > Colin Sare-Soar colin.saresoar at terrashape.co.uk > Fri Jan 12 19:21:21 PST 2024 > I cannot see the point numbers or any info. The table is blank. This is due to the fact the the .dbf sidecar file which stores the fields names and values has not been provided or has not been created at all. > Il 12/01/2024 17:11, Aurélie Tisson (BastaPrint) via QGIS-Developer ha scritto: > If my viewing area includes the point 1612, I see all > the points, well aligned, but I cannot click points 1613 and further. > If I zoom in, or if I move the area and the point 1612 is out of the > area, I see nothing anymore. It looks like this issue is due to the fact that the extent stored in the .shp and in the .shx files is incorrect. As you can see in the Layer Properties / Information dialog window, the extent stored for such layer is: 645765.5000,6860847. : 645766.3750,6860852. The points with Feature ID from 0 to 34 and from 1613 to 2000 are outside such extent. As suggested by Richard, just exporting the layer in a new ESRI Shapefile layer will write the right extent in the .shp and .shx files and the issue will not occur using the new layer. While I guess there is an issue in the code used to create the ESRI Shapefile layer, which not correctly updates the extent of the created layer, I also see some issue in QGIS itself and or in the GDAL/OGR library: - QGIS should be less strict and also display the features outside the stored extent and or warn the user about the incorrect extent - the "Updade extent" functionality in the Layer Properties / Source dialog window seems not working, at least for ESRI Shapefile layers - the "Repair Shapefile" processing algorithm (based on GDAL/OGR functionality) doesn't repair the incorrect extent stored in the .shx file. Best regards. Andrea ___ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer ___ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
