[Qgis-user] Please test length/area measurement in master

Blumentrath, Stefan Stefan.Blumentrath at nina.no
Mon Feb 15 14:34:17 PST 2016


Hi Nyall,

Thanks for your work on this issue(s) and esp. the unit tests.

I did a swift test with a 100km vector grid using master version 5d989ab (which probably does not contain all your changes?).

Area measurements are consistent across field calculator and identify tool. However, the field calculator (using an 8 digits numeric field) shows some minor and probably neglectable imprecisions (e.g. compared to GRASS). GRASS reports exacly 10000000000.00000000 m2, while the field calculator gives something like 10000000000 +/- 0.0005 (OTF off).

With OTF on measurements differ significantly compared to GRASS and OTF off, due to ellipsoidal metric used with OTF on I guess. Personally, I find this difference confusing, but I trust the difference in behavior btw. OTF on and off is a deliberate choice of the more accurate area measure?!

Choosing no measurement ellipsoid in the project settings gives the same behavior as OTF off.

Kind regards,
Stefan





-----Original Message-----
From: Qgis-user [mailto:qgis-user-bounces at lists.osgeo.org] On Behalf Of Nyall Dawson
Sent: 15. februar 2016 21:49
To: qgis-developer <qgis-developer at lists.osgeo.org>; qgis-user <qgis-user at lists.osgeo.org>
Subject: [Qgis-user] Please test length/area measurement in master

Hi all,

Just putting out a call for extensive testing of length and area measurements in the current master version. Over the past week I've done a bunch of work trying to simplify the situation regarding length/area calculation and unit handling, with the intention of closing http://hub.qgis.org/issues/13209 and the other outstanding area calculation issues (plus locking all this down with unit tests!).

I'd really appreciate thorough testing being done by users to ensure that this bug is now indeed fixed prior to the 2.14 release.

Things to check:

- measured length/area is consistent across the identify tool results, field calculator, and measure tool. (note that there's still an open bug regarding virtual fields - there's a PR open to fix this but it's not merged yet). Testing with different combinations of geographic/non geographic CRS, OTF projection on/off and various ellipsoid/planimetric calculations would be perfect.
- test the new project properties settings for project distance/area units and coordinate formats
- test the reworked options for QGIS angle units and measurement of angles using the measure tool

Thanks in advance!

Nyall
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