Min annotation scale

[dappledore]

Hello,
I am using to show locations that have distances a number of kilometers away , example 10kms, because of the distance the annotation is not visible. I have been capping the distance, in MBanchor class, so the annotation remains visible this works but what happens is i am able to walk up to the point quickly then pass it even though it is kilometers away.
So the question how to set a minimum size for an annotation, i have tried changing the scale of the scnplane in the annotationmanager but that didnt work.