[Qgis-developer] Wrong Area for large polygons in vector/Geometry Tools/Export/Add Geometry Columns

[Giovanni Manghi]

> Check, for example, polygons with ID 25967 and 26570: according to the table,
> the areas are
> 25967: 8550196769
> 26570: 1736474738
> 
> while visual inspection indicates that 26570 is obviously much larger.


this depends on

http://hub.qgis.org/issues/4955

if you compute areas (with both the filed calculator or the "add
geometry columns tool") you get

ID Area_FC
25967 8550196769.93
26570 173647473841.47

that makes sense according to the size of polygons



> Both results are different than those calculated by R:
> 
> 25967:    9294889613
> 26570: 205414657947
> 
> Discrepancies with R are particularly large for polygons with area > 1E+10


Can't understand these differences.


-- Giovanni --