System and method for deriving field boundaries using alpha shapes

• US 6,119,069 A
• Filed: 03/01/1999
• Issued: 09/12/2000
• Est. Priority Date: 03/01/1999
• Status: Expired due to Term

• Current Assignee: Blue Leaf IP Incorporated (CNH Industrial N.V.), CNH Industrial America LLC (CNH Industrial N.V.)
• Original Assignee: Case Corporation (CNH Industrial N.V.)
• Inventors: McCauley, James Darrell
• Primary Examiner(s): McElheny, Jr., Donald E.
• Application Number:
  US09/258,962
• Time in Patent Office: 561 Days
• Field of Search: 701/50, 702/5, 56/10.2 R, 56/10.2 A, 56/10.2 D, 56/10.2 F
• US Class Current: 702/5
• CPC Class Codes: G06V 10/46 Descriptors for shape, contour or point-related descriptors, e.g. scale invariant feature transform [SIFT] or bags of words [BoW]; Salient regional features colour feature extraction G06V10/56

Abstract

A system and method for determining the boundaries of a field is disclosed. The system and method utilizes computational geometry and, in particular, the alpha shape of the field to derive the field boundary of a set of georeferenced data points. The method includes collecting georeferenced data for the field, assigning the georeferenced data to a data set, filtering the data to remove anomalous data points, filtering the data to remove known inside points, scaling the point coordinates from decimal to integer form, determining the alpha shape of the set, buffering the alpha shape to compensate for antenna position, and outputting the field boundary.

Claims

1. A method of analyzing a set of georeferenced data for deriving a field boundary of a field, comprising the steps of:

receiving the georeferenced data for the field in a digital memory; and

generating an alpha shape of the georeferenced data, wherein the alpha shape represents the field boundary of the field.

2. The method of claim 1, wherein the step of receiving includes receiving georeferenced data including characteristic data representative of a spatially-variable characteristic of the field.

3. The method of claim 1, further comprising generating display signals representative of the alpha shape which, when applied to an electronic display, generate a visual indicia of the field boundary.

4. The method of claim 1, wherein the step of generating includes determining alpha.

5. The method of claim 4, wherein the step of determining alpha includes receiving the value of alpha from an operator-adjustable input device.

6. The method of claim 4, wherein the step of determining alpha includes automatically determining the smallest value of alpha that generates an alpha shape substantially free of cavities.

7. The method of claim 1, wherein the step of generating an alpha shape further comprises the steps of:

performing a Delaunay triangulation of the georeferenced data;

determining alpha;

determining alpha extreme points of the georeferenced data based on alpha;

determining alpha neighbors of the georeferenced data based on alpha; and

generating the alpha shape based on the alpha extreme points and alpha neighbors.

8. The method of claim 1 wherein the step of generating an alpha shape includes buffering the alpha shape by a predetermined distance representative of an offset between a positioning antenna and the field boundary.

9. The method of claim 1 wherein the step of generating an alpha shape includes filtering the georeferenced data to remove anomalous data points from the georeferenced data.

10. The method of claim 1 wherein the step of generating an alpha shape includes filtering the georeferenced data to remove at least a portion of the data points known to be interior to the field boundary.

11. The method of claim 1 wherein the step of generating an alpha shape includes scaling the georeferenced data from a decimal format to an integer format.

12. The method of claim 1, further comprising the steps of:

sensing a spatially-variable characteristic of the field; and

generating sensed characteristic data representative of the sensed spatially-variable characteristic, wherein the step of receiving includes receiving georeferenced data including the sensed characteristic data.

13. The method of claim 12, further comprising traversing the field in a harvesting vehicle, wherein the field is an agricultural field and the spatially-variable characteristic depends upon sensed grain flow.

14. The method of claim 12, further comprising traversing the field in a construction vehicle, wherein the field is a construction site and the spatially-variable characteristic is field grade.

15. The method of claim 1, further comprising the steps of:

sensing a spatially-variable input applied to the field; and

generating application data representative of the sensed spatially-variable input, wherein the step of receiving includes receiving georeferenced data including the application data.

16. The method of claim 1, further comprising the step of:

generating location data representative of a plurality of locations within the field, wherein the step of receiving includes receiving georeferenced data including the location data.

17. The method of claim 16, wherein the step of generating location data includes receiving location signals, receiving location correction signals, correlating the location signals with the location correction signals, and generating the location data based on the correlated location signals.

18. The method of claim 1, wherein the georeferenced data include longitude and latitude coordinates associated with each georeferenced data point.

19. An apparatus for analyzing a set of georeferenced data for deriving a field boundary of a field, comprising:

means for receiving the georeferenced data for the field in a digital memory; and

means for generating an alpha shape of the georeferenced data, wherein the alpha shape represents the field boundary of the field.

20. The apparatus of claim 19, wherein the means for receiving includes means for receiving georeferenced data including characteristic data representative of a spatially-variable characteristic of the field.

21. The apparatus of claim 19, further comprising means for generating display signals representative of the alpha shape which, when applied to an electronic display, generate a visual indicia of the field boundary.

22. The apparatus of claim 19, wherein the means for generating includes means for determining alpha.

23. The apparatus of claim 19 wherein the means for generating an alpha shape further comprises:

means for triangulating the georeferenced data;

means for determining alpha;

means for determining alpha extreme points of the georeferenced data based on alpha;

means for determining alpha neighbors of the georeferenced data based on alpha; and

means for generating the alpha shape based on the alpha extreme points and alpha neighbors.

24. The apparatus of claim 19 wherein the means for generating an alpha shape includes means for buffering the alpha shape by a predetermined distance representative of an offset between a positioning antenna and the field boundary.

25. The apparatus of claim 19 wherein the means for generating an alpha shape includes means for filtering the georeferenced data to remove anomalous data points from the georeferenced data.

26. The apparatus of claim 19 wherein the means for generating an alpha shape includes means for filtering the georeferenced data to remove at least a portion of the data points known to be interior to the field boundary.

27. The apparatus of claim 19 wherein the means for generating an alpha shape includes means for scaling the georeferenced data from a decimal format to an integer format.

28. The apparatus of claim 19, further comprising:

means for sensing a spatially-variable characteristic of the field; and

means for generating sensed characteristic data representative of the sensed spatially-variable characteristic, wherein the means for receiving includes means for receiving georeferenced data including the sensed characteristic data.

29. The apparatus of claim 28, further comprising means for traversing the field, wherein the field is an agricultural field and the spatially-variable characteristic is grain flow.

30. The apparatus of claim 28, further comprising means for traversing the field, wherein the field is a construction site and the spatially-variable characteristic is field grade.

31. The apparatus of claim 19, further comprising:

means for sensing a spatially-variable input applied to the field; and

means for generating application data representative of the sensed spatially-variable input, wherein the step of receiving includes receiving georeferenced data including the application data.

32. The apparatus of claim 19, further comprising means for generating location data representative of a plurality of locations within the field, wherein the means for receiving includes means for receiving georeferenced data including the location data.

33. The apparatus of claim 32, wherein the means for generating location data includes means for receiving location signals, means for receiving location correction signals, means for correlating the location signals with the location correction signals, and means for generating the location data based on the correlated location signals.

34. The apparatus of claim 19, wherein the georeferenced data include longitude and latitude coordinates associated with each georeferenced data point.

35. A computer program embodied on a computer-readable medium for analyzing a set of georeferenced data to derive a field boundary of a field, comprising:

means for receiving the georeferenced data for the field in a digital memory; and

means for generating an alpha shape of the georeferenced data, the alpha shape representing the field boundary of the field.

36. The computer program of claim 35, wherein the georeferenced data includes characteristic data representative of a spatially-variable characteristic of the field.

37. The computer program of claim 36, the means for generating further comprising:

means for determining alpha; and

means for filtering the georeferenced data to remove anomalous data points from the georeferenced data.

38. The computer program of claim 36, wherein the field is an agricultural field and the spatially-variable characteristic is crop yield.