Re: particle analysis-Feret diameter

> How do you propose to place the other feret diameters at n angles?
> Is this based on the image frame of reference or angles offset from the
> direction of the largest one?
> And what should one use, the centroid or the centre of mass of the particle?
> Note that when using the centre of mass, holes in the particle make it
> difficult to standardise the measurements (the same particle filled and with
> holes has different feret legths because the "centre" is in a different
> location.

Feret diameter is affected by particle orientation and the only way to 
minimize
variations due to particle orientation is to measure it at many different
angles. It doesn't matter how you rotate the particle, the dependency on
initial orientation will not go away completely. But the variation will be
minimal if many angles are used. Typically, commercial systems use from 32 to
sometimes more 72 angles, but usually 72 are sufficient.

Regards,

K.Kachrimanis.