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 |
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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)
Change History (16)
comment:1 by , 14 years ago
Version: | HEAD → 1.3.0 |
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comment:2 by , 14 years ago
comment:3 by , 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.
comment:4 by , 14 years ago
Component: | Map Legend → Projection Support |
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Milestone: | → Version 1.4.0 |
Owner: | changed from | to
Platform: | OS X → All |
Summary: | North arrow points sometimes north, sometimes south → North 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 , 14 years ago
Attachment: | qgis_screen.png added |
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follow-up: 6 comment:5 by , 14 years ago
To me, it is wrong at large and small scales. Look at the screenshots I made, always in Lambert 93 system.
comment:6 by , 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 , 14 years ago
Milestone: | Version 1.5.0 → Version 1.6.0 |
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Not quite sure it's really a bug. Further investigation needed
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.