Hi,
Sometimes it could be really tricky to find right values, as these depend a lot on the item's shape (the algorithm traces virtual bounding-
spheres) and size difference between used items (in your case rocks). Please feel free to check our
on-line reference guide for detailed description of the
Collisions feature, where you can find examples showing how different local / global
Radius values affect the final look. In your case (rocks) the default "centre" value (50%) for the
Height should be fine.
Usually, to get a compact look, it's better to combine various sizes (you can easily archive that even without preparing additional geometry by changing the
Scale value for some of your
Custom object(s)). By setting accurately the
Density value, in most cases there is no need to use the
Collisions feature (it's designed mainly for check collisions between trees).
Hope you find it useful and please feel free to post an image(s) for further clarifying.
Kind regards,