Bug report #9050

Cannot add a scalebar in meters of project is wgs84

Added by Mathieu Pellerin - nIRV about 10 years ago. Updated almost 10 years ago.

Category:Map Composer/Printing
Affected QGIS version:master Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:17702


Steps to reproduce:
1. Create a new project (projection epsg:4326)
2. Insert the attached shapefile (adm1_states_regions.zip)
3. Create a new composer window
4. Insert a map canvas item
5. Insert a scale bar item
6. First brokenness: scale bar simply shows 0 (default sane auto-fill value broken)
7. In the Units tab, make sure units is set meters, then put 1,000 has value for map unit per bar unit
8. In the segments tab, enter 1 for the size unit (which should mean that one segment will represent one unit, which represents one kilometer)
9. Second brokenness: scale bar doesn't size up to the defined bar unit / map unit values

Setting to blocker and filing this into the projection support category as my gut feeling tells me this has something to do with recent projection-related commits.

adm1_states_regions.zip.zip (852 KB) Mathieu Pellerin - nIRV, 2013-11-11 05:57 PM


#1 Updated by Giovanni Manghi about 10 years ago

  • Status changed from Open to Feedback

I'm not sure I can confirm this issue, at least how it was described.

What I see is that if the project is in wgs84, then I can get a right scalebar only if I choose map units, so degrees.

If I choose the scalebar in meters or feet I cannot get a scalebar with tight values.

This on the latest master.

#2 Updated by Mathieu Pellerin - nIRV about 10 years ago

  • Priority changed from Severe/Regression to High

So I was wrong in thinking this is a regression. The same issue is visible on QGIS 2.0. I just never ran into it as I usually work in a meter-based projection whereas I had to produce a WGS84-based map last week.

Moving forward, there's a broken behavior and an issue n the above steps:
1/ Adding a scale bar item linked to a map with a degree-based projection doesn't offer useful values (while it does linking to a meter-based map);
2/ More importantly, setting the scale bar to meter is simply broken (under QGIS 2.0, and current master).

#3 Updated by Giovanni Manghi about 10 years ago

  • Status changed from Feedback to Open
  • Category changed from Projection Support to Map Composer/Printing
  • Subject changed from qgis composer scale bar broken under qgis master to Cannot add a scalebar in meters of project is wgs84

#4 Updated by Jukka Rahkonen about 10 years ago


In WGS84 scale in meters is different in N/S and E/W directions except on top of the equator line. Would you like to see the metric scale bar to show the E/W scale even it could be very badly misleading for N/S direction?

#5 Updated by jtornero - about 10 years ago

Hello All,

maybe we could put together this issue and what I suggest in #9050 and also in PR https://github.com/qgis/QGIS/pull/995

Best regards,

Jorge Tornero

#6 Updated by Antonio Locandro almost 10 years ago

This kind of behaviour is available in other COTS software, I don't know if people actually pay attention that it could be misleading, but in my job we usually have some maps in WGS84 data and scale bars in NM

#7 Updated by Paolo Cavallini almost 10 years ago

  • Status changed from Open to Feedback

Isn't this fixed in master?

#8 Updated by Mathieu Pellerin - nIRV almost 10 years ago

  • Status changed from Feedback to Closed

I'll close this issue as it's implemented in master.

However, the implementation is currently somewhat confusing as it only works when on-the-fly reprojection is activated. If it's not activated and your not using a meter-based projection, the scale item offers meter unit but it'll be broken.

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