I have what I hope is a simple question. I'm doing convex hull calculations. What I have is area(convex_hull($geometry)).

I get a number and that's all well and fine. Since I need to get a ratio of that area with the original polygon, I need to know what units the convex hull area is in. Does anyone have an idea on this?

Also, am I doing something naive?

  • 1
    The same units as the features that generated the convex hull.. what did you create it from? – Michael Stimson Oct 17 '17 at 2:17
  • NAD 83. This makes me think I need to recheck the area of the feature to make I didn't do something weird. I figured that's what the units were, it's just that the comparison between one and the other made no sense. – Dagoski Oct 17 '17 at 2:33

This has to do with the difference between area($geometry) and $area. Once I used the former, I get numbers that make sense.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.