[GRASS-dev] [GRASS GIS] #3369: Followup to area calculation fix in changeset 71169

[GRASS GIS]

#3369: Followup to area calculation fix in changeset 71169
-------------------------+-------------------------
 Reporter:  ndawson      |      Owner:  grass-dev@…
     Type:  defect       |     Status:  new
 Priority:  normal       |  Milestone:
Component:  Default      |    Version:  unspecified
 Keywords:               |        CPU:  Unspecified
 Platform:  Unspecified  |
-------------------------+-------------------------
 While investigating the QGIS ticket https://issues.qgis.org/issues/16820 I
 came across changeset 71169 as a fix for a similar issue in grass.

 When porting this fix across to QGIS, I had to modify the thres constant
 value to 0.7e-7, outside of the 1e-4 to 1e-7 range noted in the comment in
 area_poly1.c. I found this to be the maximum possible value which allowed
 an existing QGIS regression test to pass:

 https://github.com/qgis/QGIS/blob/master/tests/src/core/testqgsdistancearea.cpp#L371
 (as a result of https://issues.qgis.org/issues/14675)

 So this ticket is just a heads-up that the grass threshold value of 1e-6
 may not be suitable, and this may need lowering to fix a real-world area
 calculation issue.

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/3369>
GRASS GIS <https://grass.osgeo.org>