Method for scanning the surface of an object

A method of filtering a digitised coordinate data signal representing coordinates of a plurality of points on a surface of a workpiece, to filter portions of said coordinate data signal representing some of the points, comprising the steps of:

• scanning the surface of the workpiece with a probe to generate the coordinate data signal,
• selecting portions of said coordinate data signal representing first, second and third points, produced in that order, on the surface,
• creating a vector extending from the first point through the third point,
• determining whether said vector lies within a predetermined tolerance distance from the second point, and
• filtering the portion representing the second point from said coordinate data signal to reject the second point if said vector lies within said tolerance distance.

A method for filtering a data signal generated by scanning the surface of a workpiece, comprising the steps of:

• scanning the surface with a probe;
• generating a data signal comprising a plurality of point position data signals, each point position data signal indicative of a position of a point of the surface relative to a predetermined coordinate system;
• filtering the data signal to remove redundant ones of the plurality of point position data signals to form a filtered data signal;
• and
• storing the filtered data signal in a memory device;
• wherein the filtering step comprises the steps of:
• selecting a point corresponding to one of the plurality of point position data signals as a base point,
• selecting another point corresponding to another of the plurality of point position data signals as a test point,
• selecting another point corresponding to another of the plurality of point position data signals as a current point, the base, test and current points located in that order on the workpiece surface,
• generating a test vector extending from the base point through the current point,
• determining if the test vector lies within a selected tolerance distance extending from the test point, and
• filtering the point position data signal corresponding to the test point from the data signal as one of the redundant ones of the plurality of point position data signals when the test vector lies within the tolerance distance.

A method for filtering a data signal generated by scanning the surface of a workpiece, comprising the steps of:

• placing the workpiece within a measuring space of a machine having a probe and a plurality of axis measuring devices, each axis measuring device generating a coordinate signal indicating a distance of the surface from an origin position along an independent axis;
• scanning the surface with the probe;
• generating a data signal comprising a plurality of point position data signals, each point position data signal indicative of a position of a point of the surface relative to a predetermined coordinate system and comprising a plurality of the coordinate signals from the plurality of axis measuring devices;
• filtering the data signal to remove redundant ones of the plurality of point position data signals to form a filtered data signal;
• and
• storing the filtered data signal in a memory device;
• wherein the filtering step comprises the steps of:
• selecting a point corresponding to one of the plurality of point position data signals as a base point,
• selecting another point corresponding to another of the plurality of point position data signals as a test point,
• selecting another point corresponding to another of the plurality of point position data signals as a current point, the base, test and current points located in that order on the workpiece surface,
• generating a test vector extending from the base point through the current point,
• determining if the test vector lies within a selected tolerance distance extending from the test point, and
• filtering the point position data signal corresponding to the test point from the data signal as one of the redundant ones of the plurality of point position data signals when the test vector lies within the tolerance distance.

A method of digitizing a surface of a workpiece, comprising the steps of:

• scanning the surface with a probe to produce a digitized coordinate data signal representing coordinates of a plurality of points on the workpiece surface;
• and
• filtering said coordinate data signal to reject portions of said coordinate data signal representing some of said points, wherein the filtering step selects portions of said coordinate data signal representing respective points on the workpiece surface in consecutive order and comprises steps of:
• (a) selecting portions of said coordinate data signal which represent first and second points on the surface, in that order, the first point being defined as a base point and the second point as a test point;
• (b) creating a tolerance band which is defined in dependence on the base and test points;
• (c) selecting a next portion from said coordinate data signal which represents a next point on the surface, said next point defined as a current point;
• (d) determining whether the current point lies within said tolerance band;
• (e) removing the portion of said coordinate data signal representing the test point and redefining the current point as a new test point if the current point does lie within said tolerance band, and redefining the test point as a new base point and the current point as a new test point if the current point does not lie within said tolerance band;
• and
• (f) repeating steps (b) through (e) for the remaining portions of said coordinate data signal, using points as redefined in step (e).