Determine location (radius) from Paraview and axes grid setting problems

Hello,

  1. I have a bunch of results like this, the black circles ( hand draw example) are changed for different results. Basically, it is the intensity of the points. I have the access to the location of each point, but I want the radius of each circle, the furthest one is easy to get (the distance between the furthest point and the center), but how about the other two, thank you so much!

  2. How to set axes grid shown once for all other files I will import.

I think you could do some kind of PCA with polar variables. I think if you put some thought into it the inner circle radius should be findable for sure

As first step I would substract the centroid to the image