I try to measure a polygon with
Export/Add geometry columns tool. The units for area measurement are square meters.
The problem is that I get different area results for the polygon:
- When the ellipsoid is WGS 84- the area result is 1809 m2 (square meters)
- When I choose
calculate using Layer CRSin the
Export/Add geometry columnstool, then the area result is 1799 m2
I don't understand:
What do I choose in the Ellipsoid field (in General tab)?
What do I choose in the "Add geometry columns" tool?
Which of the results is the right for me?