No, that's not what I mean. A point is represented by a z-value at the resolution of space. A non-point is approximated by multiple z-values, at varying resol

No, that's not what I mean. A point is represented by a z-value at the resolution of space. A non-point is approximated by multiple z-values, at varying resolutions. You can trade the accuracy of the approximation against the number of z-values. I explained the NN algorithm in another comment on this thread. It shouldn't matter if some of the adjacent z-values are actually from the approximation of the same object.