Opened 14 years ago

Last modified 14 years ago

#1993 new bug

North arrow changes direction (with OTFR disabled and projected CRS) at very high/low zoom levels

Reported by: vince Owned by: homann
Priority: minor: annoyance Milestone: Version 1.7.0
Component: Projection Support Version: 1.3.0
Keywords: north arrow Cc:
Must Fix for Release: No Platform: All
Platform Version: 10.6.1 Awaiting user input: no

Description

Depending on the zoom level, the north arrow points sometimes north, sometimes south...

Attachments (9)

dpts.zip (172.9 KB ) - added by vince 14 years ago.
Example of shapefile
qgis_screen.png (63.6 KB ) - added by lutra 14 years ago.
Capture d’écran 2009-10-11 à 09.55.45.png (103.1 KB ) - added by vince 14 years ago.
Screenshot #1
Capture d’écran 2009-10-11 à 09.55.49.png (103.7 KB ) - added by vince 14 years ago.
Screenshot 2
Capture d’écran 2009-10-11 à 09.55.51.png (105.5 KB ) - added by vince 14 years ago.
Scrrenshot 3
Capture d’écran 2009-10-11 à 09.55.56.png (143.4 KB ) - added by vince 14 years ago.
Screenshot 4
Capture d’écran 2009-10-11 à 09.55.58.png (137.9 KB ) - added by vince 14 years ago.
Scrrenshot 5
Capture d’écran 2009-10-11 à 09.56.06.png (104.1 KB ) - added by vince 14 years ago.
Screenshot 6
Capture d’écran 2009-10-11 à 09.56.11.png (103.9 KB ) - added by vince 14 years ago.
Screenshot 7

Download all attachments as: .zip

Change History (16)

comment:1 by vince, 14 years ago

Version: HEAD1.3.0

comment:2 by lutra, 14 years ago

can you post sample data? are you using a geographic or projected crs? otfr on?

please try to be more specific when posting bugs otherwise it becomes hard to check them and confirm the bug.

comment:3 by vince, 14 years ago

Ok, sorry. You will find appended a shapefile with French limits. Set project to Lambert 93 (EPSG 2154 or 2174, I don't remember) and try various zoom levels. The arrow move back and forth from north to south.

by vince, 14 years ago

Attachment: dpts.zip added

Example of shapefile

comment:4 by lutra, 14 years ago

Component: Map LegendProjection Support
Milestone: Version 1.4.0
Owner: changed from nobody to homann
Platform: OS XAll
Summary: North arrow points sometimes north, sometimes southNorth arrow changes direction (with OTFR disabled and projected CRS) at very high/low zoom levels

I'm not really very deep into projections matters, so I may not be able to explain this correctly, and if I'm saying something wrong please correct me.

Try add a layer defined in wgs84, for example a shape of the world borders: to let your France shape overlap the world borders you will need to enable OTFR. If you define wgs84 as project CRS, then you'll see obviously all aligned and the north points upwards, regardless the zoom level.

Now change the project CRS to a projected system and zoom to your France layer, you'll obviously still see the north upwards, but then when you zoom out the north arrow will start change the direction because the world border layer "wraps". It seems to me that the direction changes depending on what you have in the centre of the canvas. *

I'm not sure why this also happens when you zoom in a lot, but I see that it happens when the scale reads "4 cm", so I guess that is not really important.

I'm also not really sure why this happens with OTFR *not enabled* and the project defined with a *projected CRS*. Interestingly it seems to happen always when zooming in (a lot) regardless the projected crs, but I found that when zooming out with certain projected crs, the north arrow does not change direction. As I said I'm very scarce about this matters, so maybe there is a reason that makes perfect sense for this behaviour.

* Doing such test I found a bug that crashes qgis under ubuntu, but I will open a separate ticket.

by lutra, 14 years ago

Attachment: qgis_screen.png added

comment:5 by vince, 14 years ago

To me, it is wrong at large and small scales. Look at the screenshots I made, always in Lambert 93 system.

by vince, 14 years ago

Screenshot #1

by vince, 14 years ago

Screenshot 2

by vince, 14 years ago

Scrrenshot 3

by vince, 14 years ago

Screenshot 4

by vince, 14 years ago

Scrrenshot 5

by vince, 14 years ago

Screenshot 6

by vince, 14 years ago

Screenshot 7

in reply to:  5 comment:6 by lutra, 14 years ago

Replying to vince:

To me, it is wrong at large and small scales. Look at the screenshots I made, always in Lambert 93 system.

yes (if you are using otfr disabled), it is what I wrote in my last sentence. But again, it doesn't happens with all the projected crs, so maybe there is an explanation, maybe is a just a bug.

comment:7 by pcav, 14 years ago

Milestone: Version 1.5.0Version 1.6.0

Not quite sure it's really a bug. Further investigation needed

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