Bug report #20391

Disappearing vector lines when zooming in

Added by Mikael Vaaltola almost 2 years ago. Updated over 1 year ago.

Status:Closed
Priority:Normal
Assignee:-
Category:Vectors
Affected QGIS version:3.4.1 Regression?:No
Operating System:Ubuntu 18.04, Windows 10 Easy fix?:No
Pull Request or Patch supplied:No Resolution:invalid
Crashes QGIS or corrupts data:No Copied to github as #:28211

Description

Vector lines/tracks loaded from a gpx file disappear when zooming in. This only affects some gpx files, while others seem to work fine.

I have tested this on both QGIS 2.18 and 3.4.1. The problem is easy to reproduce:

1. Create a new project, load the attached gpx file in QGIS and add the tracks layer to the project.
2. Zoom out to see the tracks, zoom in and they disappear. The cutoff seems to be around scale 1:18000.

I found earlier bug reports of disappearing vector geometries, but they were mostly related to shape files and corrupt spatial indexes. The proposed solution of deleting the spatial index file doesn't apply to gpx files.

2018-08-29-08.47.52.gpx (312 KB) Mikael Vaaltola, 2018-11-07 08:56 AM

History

#1 Updated by Giovanni Manghi almost 2 years ago

  • Status changed from Open to Feedback

The vector has hundreds of geometry errors (auto-intersections mainly).

#2 Updated by Giovanni Manghi almost 2 years ago

It has also lines of length 0.

Clean it using Processing v.clean tool (option "rmline", Threshold 0) and you'll get a good copy.

#3 Updated by Alessandro Pasotti almost 2 years ago

I wonder if we should warn the user in some way: just seeing a layer disappear is not a good UX.

#4 Updated by Giovanni Manghi almost 2 years ago

Alessandro Pasotti wrote:

I wonder if we should warn the user in some way: just seeing a layer disappear is not a good UX.

agree (and long standing ux problem by the way).

#5 Updated by Mikael Vaaltola almost 2 years ago

Giovanni Manghi wrote:

It has also lines of length 0.

Clean it using Processing v.clean tool (option "rmline", Threshold 0) and you'll get a good copy.

Thank you, this worked perfectly. I too agree that some kind of warning would be nice, I had no idea what was causing the issue.

#6 Updated by Giovanni Manghi almost 2 years ago

Thank you, this worked perfectly. I too agree that some kind of warning would be nice, I had no idea what was causing the issue.

I think we should close this and open a feature request for the warnings.

#7 Updated by Giovanni Manghi over 1 year ago

  • Resolution set to invalid
  • Status changed from Feedback to Closed

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