hey guys..need help plz :\

Hey guys, I need help on sorting specific points from a lists that I have and to make from them a closed curve.

The original definition is made to take am image and based on the b&w shades to make closed curves - to make it look like topography map.

I managed to sort the shades from the image to different list but i'm stuck on turning these list (of points) to close curves...

i can't think of a way of solving it.

any idieas??

thank you!!