Form measuring instrument, form measuring method and form measuring program

摘要

A form measuring instrument measures a form of a surface of an object to be measured using a contact to follow the surface. A pseudo-measurement point acquirer acquires positional coordinates of the reference point of the contact as pseudo-measurement points when the contact touches the object at a plurality of locations. A normal vector generator estimates a surface or line along the pseudo-measurement points from the pseudo-measurement points to calculate normal vectors extending from the pseudo-measurement points to the surface or line. A contact model locator locates contact models which specify the surface form of the contact so as to coincide the pseudo-measurement points with reference points of the contact models and so as to coincide attitudes of the contact on measurement with attitudes of the contact models. A measurement point calculator calculates cross points as measurement points, at which the normal vectors cross the surfaces of the located contact models.