Its the value that each vertex can be from a non weighted point.
If you just slop a solid white value on a flag you get issues.
The vertex near the pole cannot move, while the vertex opposite shoould move with the last vertex only able to move by a full flag lenght.
You need to do the same math for your thing there to work and apply a paint that makes sense.
As far as the collider, I’d say it’s a sphere based on the picture