Vertical lines appear as artifacts when map has lots of layers turned on.

[qgib]

Author Name: Donovan Cameron (@saultdon)
Original Redmine Issue: 11746
Affected QGIS version: 2.6.0
Redmine category:map_canvas

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I've been noticing on Windows (haven't seen this problem in Linux), is that for maps that have lots of layers (50+) vertical lines start to appear from various layers. Always random and doesn't affect specific layers or different scales.

This happens to mostly to lines and polygons. Not sure if it's relevant but the layers are from a PostGIS database.

Feature simplification is turned off, tried testing with multi-core rendering toggled on/off as well.

Even though layers are turned on, most are scale based.

Installed QGIS 2.6 with OSGeo4W installer.

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• Untitled.jpg (Donovan Cameron)
• 11746.png (Giovanni Manghi)
• vertical_lines_noplugins_nocustomization.png (Donovan Cameron)

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Related issue(s): #19717 (relates)
Redmine related issue(s): 11441

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[qgib]

Author Name: Giovanni Manghi (@gioman)

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• category_id was configured as Map Canvas

[qgib]

Author Name: Donovan Cameron (@saultdon)

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Been doing some more testing and it looks like it doesn't matter how many layers are in the project.

Even a single layer will do this when the "Render layers in parallel using many CPU cores" option is enabled.

Disabling that option fixes the issue.

Or reducing the number of cores used (on an 8 core Intel CPU i7) to 3 or less seems to reduce the artifacts. But they do appear randomly.

And this is only observed on Windows 7 and 8.1 x64 using the OSGeo4W installer. Haven't tested with standalone builds.

[qgib]

Author Name: Donovan Cameron (@saultdon)

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Looks like it doesn't have anything to do with the amount of layers and it's only on Windows (7 and 8.1 64-bit) from OSGeo4W.
Tested on Arch Linux and can't reproduce there, but those are daily builds from the 2_12 branch.

So on Windows, we're able to reproduce the issue by adding a couple layers (from PostgreSQL 9.4.5 and PostGIS 2.2.0) in EPSG:3005 (BC Albers), then enabling OTF to something like EPSG:26910.
Then once we start panning and zooming the vertical lines appear like in the screenshot originally attached.

I'll test QGIS Master on Windows from the OSGeo4W installer and report back =)
Turning off multi-core rendering will reduce the artifacts and frequency, but not entirely.

[qgib]

Author Name: Donovan Cameron (@saultdon)

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Seeing the same rendering issues in Master (2.13.0, 3e61891) and Current Release (2.12.0, cd9d645) on Windows from OSGeo4W.

I can add a few layers in EPSG:3005, then turn OTF on to anything like EPSG:26910 and vertical lines appear.

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

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Can you share your data? Has it got Z/M coordinates?

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• status_id was changed from Open to Feedback

[qgib]

Author Name: Donovan Cameron (@saultdon)

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Some of the most culprit layers can be obtained from public FTPs in BC.

Large files though (they're province wide), and I've uploaded them to PostGIS databases using gdal forcing 2D with '-dim 2' because no layers contain z-values but some layers will be used for topology (routing) later, but currently no M values.

Invalid geometries have been repaired too.

Road Network
ftp://ftp.geobc.gov.bc.ca/sections/outgoing/bmgs/DRA_Public/dgtl_road_atlas.gdb.zip (256 MB)

Fresh Water Atlas
ftp://ftp.geobc.gov.bc.ca/sections/outgoing/bmgs/FWA_Public/FWA_BC.gdb.zip (3.5 GB)

The Fresh Water Atlas has a good mix of layers that have different types of geometries like lakes/rivers (polygon), stream network (line), wetland (polygon), etc. Load at least those 3 layers (and the road network mpar layer) to see the vertical lines. These layers seem to be doing it the most (maybe it's because they have the most nodes?).

[qgib]

Author Name: Donovan Cameron (@saultdon)

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I'm able to reproduce it easily now =)

I add the Digital Road Atlas (layer that ends in mpar) which is in EPSG:3005.

Then I add some layers from ftp://ftp2.cits.rncan.gc.ca/pub/geott/frameworkdata/hydrology/cartographic/canada/canaddrcarto_1m_v6-0.shp.zip (94.4 MB) which are some water course and body layers but in EPSG:4269 so that turns OTF on (projecting to EPSG:3005).

Then I can see the vertical lines from the water course and body layers.

This means you might not have to download the FWA dataset to test it out.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Donovan Cameron wrote:

I'm able to reproduce it easily now =)

I add the Digital Road Atlas (layer that ends in mpar) which is in EPSG:3005.

Then I add some layers from ftp://ftp2.cits.rncan.gc.ca/pub/geott/frameworkdata/hydrology/cartographic/canada/canaddrcarto_1m_v6-0.shp.zip (94.4 MB) which are some water course and body layers but in EPSG:4269 so that turns OTF on (projecting to EPSG:3005).

Then I can see the vertical lines from the water course and body layers.

This means you might not have to download the FWA dataset to test it out.

no problems here under Windows 7/QGIS master, see attached image

You can also want to test the linked project + data (to avoid having to download that big datasets referred above).

https://www.dropbox.com/s/dlphmmqpjvb0xwe/test_11746.zip?dl=0

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• 9414 was configured as 11746.png

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• 11746.png (Giovanni Manghi)

[qgib]

Author Name: Giovanni Manghi (@gioman)

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closing for lack of feedback, please reopen of necessary.

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• status_id was changed from Feedback to Closed
• resolution was changed from to worksforme

[qgib]

Author Name: Donovan Cameron (@saultdon)

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Thanks for testing Giovanni.

I've uploaded something similar in 7z and zip - both the same and with the full datasets, but with a project file like yours.

https://dl.dropboxusercontent.com/u/33592962/outgoing/qgis/qgis_vertical_lines.zip (120MB)
https://dl.dropboxusercontent.com/u/33592962/outgoing/qgis/qgis_vertical_lines.7z (86MB)

I noticed the vertical lines are really coming out when there are only a couple layers and zoomed out. I attached an image.
Or if there are lots of layers, when zoomed in.

I loaded the project in QGIS and QGIS Master (installed from OSGeo4W) using the --noplugins --nocustomization options to be sure it wasn't a rogue plugin or customization.
Getting the same result on both Windows 8.1/7 64bit.

Linux is working great where I don't see any artefacts, but there are lots of "Warnings" in the console.

Warning: Could not resolve property : linearGradient4548
...

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• 9446 was configured as vertical_lines_noplugins_nocustomization.png

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• vertical_lines_noplugins_nocustomization.png (Donovan Cameron) - showing vector artefacts in qgis

[qgib]

Author Name: Donovan Cameron (@saultdon)

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Forgot to reopen so that's what this post is for.

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• status_id was changed from Closed to Reopened

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• resolution was changed from worksforme to

[qgib]

Author Name: Donovan Cameron (@saultdon)

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I also noticed that the problem almost completely disappears when "Render layers in parallel using many CPU cores" is turned off.
There is still the rare vector off shoot problem from both lines and polygons but now it seems to only show one or two artefacts, and then a pan or refresh gets rid of it for a good while.

I noticed it's also re-drawing the geometries.

So a line that was like ......... now looks like ..../\....

So it's like it's moving nodes/vertices around for some reason.

[qgib]

Author Name: Martin Dobias (@wonder-sk)

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I believe this is a duplicate of #19717

Please see my comment here and test with newest version of proj4 library: #19717 (comment)

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• status_id was changed from Reopened to Feedback

[qgib]

Author Name: Donovan Cameron (@saultdon)

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Hey Martin, seems to still exist in 2.14.0 (Essen), so I'll close this report because it is a duplicate and follow the progress on the other report.

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• status_id was changed from Feedback to Closed