function getScaleFactor(max, min) {
    return 1 / ((max - min) / 2);
}
Determines scale amount for a given axis to normalize model coordinates.

@method
@private

@param {Number} max Maximum scale value of given axis on the model.
@param {Number} min Minimum scale value of given axis on the model.

@return {Number} Number by which the given axis should be scaled for all vertices.