[GIS] Creating a circle with radius in metres

areapythonshapelyunits

I am using shapely and Python.

How should I go about creating a circle using shapely whose radius is in meters?

If i use

sampleCircle = Point(1,1).buffer(1)
print sampleCircle.area

This returns an area of 3.13654849055. How do I interpret the unit of this area? I read that this can be interpreted in square degrees but seek a little more explanation.

Also, how do I create a circle with a specified radius (in meters) around a point (defined using lat,long)?

The closest article I found was this [http://comments.gmane.org/gmane.comp.python.gis/1582] but it lacks any concrete solution

Best Answer

By design Shapely is unaware of coordinate reference systems or units. To use it to solve real world problems, you must learn to transform longitude and latitude to an approximately planar local reference system (like a US State Plane) and you must keep track of your own units. I use pyproj to do this, but you can use whatever you want. Once you've transformed your long and lat degrees to x and y meters, Point(x, y).buffer(1.0).area is the area in m^2 of your circle (64-sided polygon to be precise).

Related Question