Ball Size

– It is related to a spherical distance (radius) within which, if another vertex of the same mesh enters, the vertex starts to deflect in order to avoid a self-collision.
– If the Calculation Type algorythm Type is set to ‘Manual’ then the ‘Ball Size’ directly sets the ball size.
– If the Calculation Type algorythm is set to ‘Average’, Minimal’, ‘Maximal’ or ‘AvMinMax’ then ‘Ball Size’ acts as a multiplicative factor for the result of the algorythm

– In this first example I did not compare two different values as I found better to render the same scene with the spheres having the radius set in the Ball Size field (Calculation Type: Manual).
– Note how vertexes collide without touching, in this scenario 0.5 is too high:

– Another example with a smaller value, it produces a better simulation right?

– So, if we set the Ball Size to a very small value the simulation will be better? No! Not only it depends from the mesh but also too low values will let other vertices get too close and thus possibly intersect because there will not be enough time to slow them down.

– In this example I compared two values for the Ball Size parameter. A too small one (the sphere is not rendered as really too small) and a too big one, both leading to a probably unwanted result:

Blender Soft Body Self Collision Ball Size