Somebody classified my question as a duplicate but applying the answer doesn't work for me.
Here is what I did:
- I made sure that my layer is in a projected coordinate system (UTM30N, WGS84)
- I used the field calculator
- I used the area command.
- I get 0.
- And I don't know where to adjust the units...
I have gps data from around 200 farm areas and I want to compute the correct area of each polygon. What I did so far is this:
I imported the data from around 10 garmin devices to basecamp, gave them IDs and exported them in one gpx-file (around 2 MB). Than I imported the GPS data to qgis and used the "line to polygon" tool to generate shapefiles.
My coordinate system is WGS 84 and UTM 30N for the south west of Burkina Faso. The whole project in qgis as well as the layers have this coordinate system.
When I create a new column in the attribute table, open the field calculator and use the "area" command, I get a "0" for each polygon. When I use the measure tool I get very small figures (f.e. 0.024 m2 instead of 43.635 ha).
I use QGIS 1.7.0 (Wroclaw) on a MacBookPro Mac OS X (10.5.8).
