Method and apparatus for obtaining coordinates describing three-dimensional objects of complex and unique geometry using a sampling probe

A method for sampling the surface of an object, comprising the steps of:

• affixing a probe in a position fixed relative to the object, the probe providing a position signal corresponding to a position of a tip of the probe in a reference coordinate system;
• selecting an origin for the probe with reference to the object;
• probing said object with the tip of the probe to obtain a sequence of position signals;
• determining a distance from the selected origin to the tip of the probe for said position signals;
• storing only improved points in a memory according to the determined distance and the position of the tip of the probe;
• determining when an adequate number of samples has been taken;
• and
• periodically displaying the position of the tip of the probe and an indication of the adequacy of sampling to a user.

A data processing system for obtaining a three dimensional representation of an object with complex and unique geometry, using a sampling probe having a tip for tracing the surface of the object, the system comprising:

• means for receiving electrical signals indicative of the position of the tip of the probe in a reference coordinate system;
• means, responsive to the means for receiving, for determining an origin with reference to the object;
• means for storing a plurality of distances, each distance corresponding to a given direction from the origin, the means for storing being addressable by the directions to store and to retrieve the corresponding distances;
• means, responsive to a signal received by said means for receiving, for determining the direction and distance of the tip of the sampling probe with reference to the origin;
• means for comparing the distance determined to any distance stored in the means for storing corresponding to the determined direction and for storing the determined distance in the means for storing when the determined distance is less than any stored distance.

A data processing system for obtaining a digitized representation of a surface of an object, comprising:

• a memory in which an application program defined by a plurality of program steps stored;
• a central processor;
• a bus connecting the memory to the processor;
• the central processor controlling data flow and data manipulation by executing program steps of the application program;
• a probe input system which receives electrical signals from a probe having a tip which electrical signals are indicative of a position of the tip of the probe in a reference coordinate system;
• wherein the central processing unit, while executing the program steps, acts as a:
• means, responsive to signals received by the probe input system, for defining a reference surface and an origin with reference to the objects;
• means, responsive to each tip position indicated by the sequence of electrical signals, for projecting the position onto a subregion of the reference surface, and for determining the distance of the tip from the origin, and for replacing, in the memory, any previously stored distance for the subregion with the determined distance when the determined distance is less than the previously stored distance for the subregion;
• means, responsive to the means for determining, for determining whether enough tip positions have been obtained;
• and
• means, for indicating to a user the tip position with reference to the reference surface.

A method for sampling the surface of an object, comprising the steps of:

• affixing a probe in a location having a fixed spatial relationship with the object, the probe providing a position signal corresponding to a position of a tip of the probe in a reference coordinate system;
• selecting an origin with reference to the object such that the distance from any point on the surface of the object to the origin in any direction of interest is shorter, than the distance from any point to the origin in the same direction which is not on the surface of the object;
• probing the object with the tip of the affixed probe to obtain a sequence of position signals;
• determining a distance from the selected origin of the probe for each of said position signals;
• and
• projecting the tip position onto a subregion of the reference surface;
• and
• replacing in a memory any previously stored distance for the subregion with the determined distance when the determined distance is less than the previously stored distance for the subregion.

A method for sampling the surface of an object, comprising the steps of:

• affixing a probe in a location having a fixed spatial relationship with the object, the probe providing a position signal corresponding to a position of a tip of the probe in a reference coordinate system;
• selecting an origin with reference to the object such that the distance from any point on the surface of the object to the origin in any direction of interest is shorter than the distance from any point to the origin in the same direction which is not on the surface of the object;
• probing the object with the tip of the affixed probe to obtain a sequence of position signals;
• storing a plurality of distances, each distance corresponding to a given direction from the origin;
• determining a distance and a direction from the selected origin of the probe for each of said position signals;
• and
• comparing the determined distance to any stored distance for the determined direction and storing the determined distance when the determined distance is less than any stored distance.