curved labels: only a few are drawn #12173

qgib · 2009-11-18T23:47:25Z

Author Name: Paolo Cavallini (@pcav)
Original Redmine Issue: 2113
Affected QGIS version: 3.2
Redmine category:labelling

With the new labelling engine, I always get far too few labels when selection the "curved" option. See attached screenshot an sample file.

labels.png (Paolo Cavallini)
fiumi-princ.zip (Paolo Cavallini)
labels2-composer.png (Borys Jurgiel)
labels2-printout.pdf (Borys Jurgiel)
P1080123_cropped_1.jpg (Alister Hood)
qgis_2113_parallel.png (Tom Grundy)
qgis_2113_curved.png (Tom Grundy)

Related issue(s): #15916 (relates), #19124 (duplicates)
Redmine related issue(s): 6763, 10740

qgib · 2009-11-19T02:30:27Z

Author Name: Martin Dobias (@wonder-sk)

The problem is that either the shapes are too short (the label wouldn't fit on the line) or the shapes are too complex and creation of labels candidates fails because the succesive characters would be otherwise rotated "too much", resulting in unreadable labels.

I don't know what should be a correct solution for this. The engine could try to detect such complex shapes and try to simplify on-the-fly them before creating candidates...

qgib · 2010-07-06T21:23:03Z

Author Name: Borys Jurgiel (@borysiasty)

Even on simpler lines, as streets, the curvature threshold seems too low. I can imagine much more curved labels would be still good-looking. Anyway, even if it's acceptable on display, on printouts (or exported files; no matter rasterized or not) it is definitely not. See screenshots label2-* (also wrong scaling and #12856 are visible).

qgib · 2011-02-10T18:30:52Z

Author Name: Alister Hood (@AlisterH)

(sorry, I was meant to post this before attaching)

I agree with this:

Even on simpler lines, as streets, the curvature threshold seems too low.

But I also think that this is necessary:

The engine could try to detect such complex shapes and try to simplify on-the-fly them before creating candidates...

See the labelling on the roads in P1080123_cropped_1.jpg for an example.

qgib · 2011-07-25T07:15:29Z

Author Name: Paolo Cavallini (@pcav)

pull_request_patch_supplied was configured as 0
tracker_id was changed from 1 to 4
start_date was configured as 2011-07-25

qgib · 2011-12-16T12:58:09Z

Author Name: Giovanni Manghi (@gioman)

fixed_version_id was changed from Version 1.7.0 to Version 1.7.4

qgib · 2012-04-15T07:22:55Z

Author Name: Giovanni Manghi (@gioman)

version was configured as master
tracker_id was changed from 4 to 1
crashes_corrupts_data was configured as 0

qgib · 2012-04-16T03:16:22Z

Author Name: Giovanni Manghi (@gioman)

see also #14688

operating_system was changed from Debian to
priority_id was changed from Low to Normal
status_info was changed from 0 to

qgib · 2012-04-16T04:22:41Z

Author Name: Paolo Cavallini (@pcav)

fixed_version_id was changed from Version 1.7.4 to Version 1.8.0

qgib · 2012-07-28T03:13:55Z

Author Name: Giovanni Manghi (@gioman)

category_id was changed from Symbology to Labelling

qgib · 2012-09-04T10:04:16Z

Author Name: Paolo Cavallini (@pcav)

fixed_version_id was changed from Version 1.8.0 to Version 2.0.0

qgib · 2012-09-15T23:24:58Z

Author Name: Giovanni Manghi (@gioman)

assigned_to_id was changed from Martin Dobias to Larry Shaffer

qgib · 2012-11-17T04:15:03Z

Author Name: Anita Graser (@anitagraser)

priority_id was changed from Normal to High

qgib · 2012-11-27T16:44:33Z

Author Name: Larry Shaffer (Larry Shaffer)

See #15916 (comment) for update on related issue.

Please test with ee12df2 and inside and outside angles greater than 20 to see higher label count (especially if you still have the original data). Some comparison screen snaps again would be nice.

Any settings higher than inside of 30 or outside of 50 (and possibly lower in some cases) will start producing some funky-looking labels. QGIS <= 1.8 had a setting of 20 for both angles.

status_id was changed from Open to In Progress

qgib · 2012-12-30T08:51:00Z

Author Name: Giovanni Manghi (@gioman)

priority_id was changed from High to Normal

qgib · 2014-01-30T22:43:32Z

Author Name: Paolo Cavallini (@pcav)

fixed_version_id was changed from Version 2.0.0 to Future Release - High Priority

qgib · 2014-06-30T00:19:11Z

Author Name: Paolo Cavallini (@pcav)

Still far from optimal

qgib · 2014-06-30T00:20:28Z

Author Name: Paolo Cavallini (@pcav)

Partly duplicated in #19124

qgib · 2014-06-30T08:54:16Z

Author Name: aperi2007 - (aperi2007 -)

Hi,
in #19124.
I give a potential solution.
My solution is to enhance the code to support an optionally second change to not lost any label that don't allow to be curved. Putting it parallel.

It is quite flexible because it give the grant to not lost any label.

Actually no one of out power users use the curve string solution. Because they are always the question to know if lost any label.
Out map infct could not lost any label.And so they use always the parallel strings to be sure to have all the labels.

I guess the parallel string as an otherwise solution could be supported using a checkbox to active it optionally.
This probably could help to use the curve solution.

I like to know if this feature could be accepted.

Please note that don't mean that we are capble to fund this solution.
This is only a proof of concept to understand if there is a potential solution for this.

One time to decide what is the solution.
The second point is understand how much cost to develope it.
:)

Regards,

Andrea.

qgib · 2014-07-01T02:48:49Z

Author Name: Paolo Cavallini (@pcav)

As discussed on the mailing list long ago, probably the best approach would be to simplify (generalize) complex (multi)lines on the fly, so that the labels will follow the best approximation to the original curve, without becoming too garbled or disappearing altogether.
I suggest to use a similar approach to geometry simplification done by Alvaro, maybe even some of the same functions.

qgib · 2014-07-01T03:54:00Z

Author Name: aperi2007 - (aperi2007 -)

The simplify approach is could be affordable for a print goal .
But could be too slowly for a web browsing map.

Almost if the question is a run-time simplify approach.

Are you speaking of an extra layer maually added to the project and simplified previously offline.
Rendered also with 100% transparency and used to obtain the curved label ?

I guess the primary question is not resolved however.
Infact after the simplify, no-one could know if the simplify was sufficient to avoid the lost of the label.

Or you are speaking of an iterative simplification increasing the simplify untile the label could appear ?

This could work but I guess it could be mortally slow.
Not more on qgis-desktop where the asynchornocity of the multithread could assure to do this meanwhile qgis do other thinks,
but instead on qgis-server where the mp is before produce and after send.

It could slow the map production of an impredictable time due to the situation of label on that portion f map.

A.

qgib · 2014-07-01T03:57:12Z

Author Name: Paolo Cavallini (@pcav)

I suggest the same approach as Alvaro OTF simplification, which is actually quite fast.
The default could be crafted so as to show all the labels, or this could be forced with an option.

qgib · 2014-07-21T21:32:03Z

Author Name: aperi2007 - (aperi2007 -)

Hi,

we like to understand if this problem is resolvable or not.

The solution proposed:

As discussed on the mailing list long ago, probably the best approach would be to simplify (generalize) complex
(multi)lines on the fly, so that the labels will follow the best approximation to the original curve, without
becoming too garbled or disappearing altogether.

I guess in not a sure solution.
I understand it augment the statistically of label curved used, and reduce the statistical of label lost, but we need to have Label Lost = 0 (zero) .

The try to introduce this need n a simplifiy algorithm will introduce an iterative procedure that could put the time to elaborate to infinite.

I guess to grant this is necessary to introduce a rule specific like this:
is the single label is not fittable in a curved line it will put parallel.

qgib · 2017-04-30T23:09:59Z

Author Name: Giovanni Manghi (@gioman)

regression was configured as 0
easy_fix was configured as 0

qgib · 2018-01-29T17:40:44Z

Author Name: Paolo Cavallini (@pcav)

Still true in master.

qgib · 2018-02-24T14:15:50Z

Author Name: Paolo Cavallini (@pcav)

assigned_to_id removed Larry Shaffer
version was changed from master to 3.0.0

qgib · 2018-10-14T17:52:01Z

Author Name: Tom Grundy (Tom Grundy)

This problem still exists in 3.2.1. I tried increasing letter spacing and changing to all-caps for the letter sizes to be more predictable, but did not see any improvement. Images attached with labeling set to parallel and another with labeling set to curved with no other changes.

13497 was configured as qgis_2113_parallel.png
13498 was configured as qgis_2113_curved.png

qgis_2113_parallel.png (Tom Grundy)
qgis_2113_curved.png (Tom Grundy)

qgib · 2018-10-14T21:20:55Z

Author Name: Giovanni Manghi (@gioman)

status_id was changed from In Progress to Open
version was changed from 3.0.0 to 3.2

conjunction with the "merge connected lines" setting Refs qgis#12173

with line networks that contains forks and branches And simplify memory management Refs qgis#12173

Refs qgis#12173

conjunction with the "merge connected lines" setting Refs #12173

with line networks that contains forks and branches And simplify memory management Refs #12173

Refs #12173

nyalldawson · 2019-05-30T07:28:50Z

With #29994 I think this can be safely closed -- the remaining todo is allowing curved labels to overlap the ends of features, but that's an existing feature request: #15846

Refs qgis#12173 (cherry picked from commit 0b451b2)

Refs #12173 (cherry picked from commit 0b451b2)

conjunction with the "merge connected lines" setting Refs qgis#12173 (cherry picked from commit 7213030)

with line networks that contains forks and branches And simplify memory management Refs qgis#12173 (cherry picked from commit e0aa09c)

conjunction with the "merge connected lines" setting Refs #12173 (cherry picked from commit 7213030)

with line networks that contains forks and branches And simplify memory management Refs #12173 (cherry picked from commit e0aa09c)

qgib added Bug Either a bug report, or a bug fix. Let's hope for the latter! Labeling Related to QGIS map labeling labels May 24, 2019

qgib added this to the Future Release - High Priority milestone May 24, 2019

nyalldawson self-assigned this May 28, 2019

nyalldawson added a commit to nyalldawson/QGIS that referenced this issue May 28, 2019

[labeling] Fix missing labels when multilinestring features are used in

b0e9316

conjunction with the "merge connected lines" setting Refs qgis#12173

nyalldawson added a commit to nyalldawson/QGIS that referenced this issue May 28, 2019

[labeling] Ensure "merge connected features" setting works correctly

e66f937

with line networks that contains forks and branches And simplify memory management Refs qgis#12173

nyalldawson added a commit to nyalldawson/QGIS that referenced this issue May 28, 2019

Fix some curved labels randomly disappear at certain scales

6f5b7b0

Refs qgis#12173

nyalldawson added a commit that referenced this issue May 30, 2019

[labeling] Fix missing labels when multilinestring features are used in

7213030

conjunction with the "merge connected lines" setting Refs #12173

nyalldawson added a commit that referenced this issue May 30, 2019

[labeling] Ensure "merge connected features" setting works correctly

e0aa09c

with line networks that contains forks and branches And simplify memory management Refs #12173

nyalldawson added a commit that referenced this issue May 30, 2019

Fix some curved labels randomly disappear at certain scales

0b451b2

Refs #12173

nyalldawson closed this as completed May 30, 2019

nyalldawson added a commit to nyalldawson/QGIS that referenced this issue Jun 3, 2019

Fix some curved labels randomly disappear at certain scales

0888ed0

Refs qgis#12173 (cherry picked from commit 0b451b2)

nyalldawson added a commit that referenced this issue Jun 3, 2019

Fix some curved labels randomly disappear at certain scales

c634150

Refs #12173 (cherry picked from commit 0b451b2)

nyalldawson added a commit to nyalldawson/QGIS that referenced this issue Jun 10, 2019

[labeling] Fix missing labels when multilinestring features are used in

1818627

conjunction with the "merge connected lines" setting Refs qgis#12173 (cherry picked from commit 7213030)

nyalldawson added a commit that referenced this issue Jun 10, 2019

[labeling] Fix missing labels when multilinestring features are used in

2ecda15

conjunction with the "merge connected lines" setting Refs #12173 (cherry picked from commit 7213030)

nyalldawson added a commit that referenced this issue Jun 10, 2019

[labeling] Ensure "merge connected features" setting works correctly

f298a85

with line networks that contains forks and branches And simplify memory management Refs #12173 (cherry picked from commit e0aa09c)

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

curved labels: only a few are drawn #12173

curved labels: only a few are drawn #12173

qgib commented Nov 18, 2009 •

edited

Loading

qgib commented Nov 19, 2009

qgib commented Jul 6, 2010 •

edited

Loading

qgib commented Feb 10, 2011

qgib commented Jul 25, 2011

qgib commented Dec 16, 2011

qgib commented Apr 15, 2012

qgib commented Apr 16, 2012 •

edited

Loading

qgib commented Apr 16, 2012

qgib commented Jul 28, 2012

qgib commented Sep 4, 2012

qgib commented Sep 15, 2012

qgib commented Nov 17, 2012

qgib commented Nov 27, 2012 •

edited

Loading

qgib commented Dec 30, 2012

qgib commented Jan 30, 2014

qgib commented Jun 30, 2014

qgib commented Jun 30, 2014 •

edited

Loading

qgib commented Jun 30, 2014 •

edited

Loading

qgib commented Jul 1, 2014

qgib commented Jul 1, 2014

qgib commented Jul 1, 2014

qgib commented Jul 21, 2014

qgib commented Apr 30, 2017

qgib commented Jan 29, 2018

qgib commented Feb 24, 2018

qgib commented Oct 14, 2018

qgib commented Oct 14, 2018

nyalldawson commented May 30, 2019

curved labels: only a few are drawn #12173

curved labels: only a few are drawn #12173

Comments

qgib commented Nov 18, 2009 • edited Loading

qgib commented Nov 19, 2009

qgib commented Jul 6, 2010 • edited Loading

qgib commented Feb 10, 2011

qgib commented Jul 25, 2011

qgib commented Dec 16, 2011

qgib commented Apr 15, 2012

qgib commented Apr 16, 2012 • edited Loading

qgib commented Apr 16, 2012

qgib commented Jul 28, 2012

qgib commented Sep 4, 2012

qgib commented Sep 15, 2012

qgib commented Nov 17, 2012

qgib commented Nov 27, 2012 • edited Loading

qgib commented Dec 30, 2012

qgib commented Jan 30, 2014

qgib commented Jun 30, 2014

qgib commented Jun 30, 2014 • edited Loading

qgib commented Jun 30, 2014 • edited Loading

qgib commented Jul 1, 2014

qgib commented Jul 1, 2014

qgib commented Jul 1, 2014

qgib commented Jul 21, 2014

qgib commented Apr 30, 2017

qgib commented Jan 29, 2018

qgib commented Feb 24, 2018

qgib commented Oct 14, 2018

qgib commented Oct 14, 2018

nyalldawson commented May 30, 2019

qgib commented Nov 18, 2009 •

edited

Loading

qgib commented Jul 6, 2010 •

edited

Loading

qgib commented Apr 16, 2012 •

edited

Loading

qgib commented Nov 27, 2012 •

edited

Loading

qgib commented Jun 30, 2014 •

edited

Loading

qgib commented Jun 30, 2014 •

edited

Loading