In this style, the radius can be scaled from an arbitrary function of column values in the input source table. This is a two-stage process:
radius = maxradius * max(1 + 0.5 * log10(proto-radius / max(proto-radius)), 0.2)The result is the radius in image pixels. Here `maxradius' (in image pixels) is supplied via the parameter maxradius.
Some users find this a bit too `foolproof' for complete satisfaction, so I may in the future either make it simpler (ie dispense with the second step above altogether) or at least allow the option for WYSIWYG setting of radii.