[GRASS-user] v.to.db area calculations

[Moritz Lennert]

Le 19 mai 2017 10:41:29 GMT+02:00, James Duffy <james.philip.duffy at gmail.com> a écrit :
>Output from ogrinfo:
>
>INFO: Open of `C:\Sandbox\RGRASS\DATA\training_single.shp'
>
>      using driver `ESRI Shapefile' successful.
>
>
>Layer name: training_single
>
>Metadata:
>
>  DBF_DATE_LAST_UPDATE=2017-05-17
>
>Geometry: Polygon
>
>Feature Count: 1
>
>Extent: (73.213474, 0.225604) - (73.213477, 0.225608)
>
>Layer SRS WKT:
>
>GEOGCS["WGS 84",
>
>    DATUM["WGS_1984",
>
>        SPHEROID["WGS 84",6378137,298.257223563,
>
>            AUTHORITY["EPSG","7030"]],
>
>        AUTHORITY["EPSG","6326"]],
>
>    PRIMEM["Greenwich",0,
>
>        AUTHORITY["EPSG","8901"]],
>
>    UNIT["degree",0.0174532925199433,
>
>        AUTHORITY["EPSG","9122"]],
>
>    AUTHORITY["EPSG","4326"]]
>
>id: Integer64 (10.0)


Ok, so the data is in degrees and 0.127 is not in m2, but in degree2 which is not a really useful unit as its meaning on the ground depends on the latitude.

Moritz

>
>
>On 19 May 2017 at 09:38, Moritz Lennert <mlennert at club.worldonline.be>
>wrote:
>
>>
>>
>> Le 19 mai 2017 10:19:06 GMT+02:00, "Blumentrath, Stefan" <
>> Stefan.Blumentrath at nina.no> a écrit :
>> >Just checked the data you send offline in QGIS 2.18.0.
>> >
>> >With your sample data
>> >SAGA (through processing) returns an area of 0.0000…
>> >QGIS with OTF ON: 34,815 m²
>> >QGIS with OTF OFF: 0,127 m²
>>
>> In what projection is the original data ?
>>
>> Moritz
>>
>>
>> >
>> >Cheers,
>> >Stefan
>>