System and method for georeferencing digital raster maps

• US 20010033291A1
• Filed: 03/29/2001
• Published: 10/25/2001
• Est. Priority Date: 03/29/2000
• Status: Active Grant

• Current Assignee: Sourceprose Corporation (TransUnion Corporation)
• Original Assignee: Sourceprose Corporation (TransUnion Corporation)
• Inventors: Higgins, Darin Wayne, Scott, Dan Martin
• Granted Patent: US 7,190,377 B2
• Time in Patent Office: Days
• US Class Current: 345/629
• CPC Class Codes: G06T 17/05 Geographic models

Abstract

The preferred embodiment provides a system and method for georeferencing digital raster maps by associating specific points on the raster map with corresponding points on a georeferenced vector map or another georeferenced raster map. According to the preferred embodiment, a raster map and a corresponding vector map are simultaneously displayed to a user. The user then locates a common geographic point or feature on each map, and marks each of them as a unique point-pair. When the user has marked at least two point-pairs, the system then computes a georeferencing function, based on the pixel-coordinates of the points marked on the raster map and the corresponding geographic coordinates of the points on the vector map. Thereafter the geographic coordinates of any point on the map may be easily computed. The preferred embodiment provides that as more point-pairs are identified, the georeferencing function is modified for increased accuracy.

Claims

1. A method of georeferencing a raster map, comprising:

providing for display a first map and a second map, the first map being a digital raster map, and the second map being a previously georeferenced map;

the fist map being substantially similar to the second map when displayed;

receiving an entry identifying a first point pair point on the first map;

receiving an entry identifying a second point pair point on the second map, the second point pair point having approximately the same location on the second map as the first point pair point has on the first map;

assigning a point pair point on the first map a longitude coordinate and a latitude coordinate, the longitude coordinate and the latitude coordinate of the first point pair point being identical to a longitude point and a latitude point associated with a point pair point on the second map.

2. The method of

claim 1

wherein the second map is a vector map.

3. The method of

claim 1

wherein the second map is a digital raster map.

4. The method of

claim 1

wherein the point pair point on the first map has a previously determined longitude and latitude.

5. The method of

claim 1

further comprising creating a georeferencing function.

6. The method of

claim 5

wherein the georeferencing function is a linear transformation.

7. The method of

claim 1

further comprising selectively synchronizing, responsive to a user command, the first map and the second map.

8. The method of

claim 1

further comprising receiving a mark on the first map at a location, and reproducing the mark on the second map at a corresponding location.

9. The method of

claim 5

wherein georeferencing uses at least three point pairs to complete the georeferencing function for the first map based on a linear transformation.

10. The method of

claim 5

further comprising using at least four point pairs to complete the georeferencing function for the first map, based on a linear transformation, and further comprising executing a validation check.

11. The method of

claim 10

further comprising rejecting a point pair when the point pair deviates a pre-determined amount from a pre-determined standard error.

12. The method of

claim 11

wherein the predetermined standard error uses a “

least square”

parameter fitting operation.

13. The method of

claim 1

further comprising:

receiving a selection of a point pair on the first map, and

receiving a selection of a point pair on the second map.

14. A method in a computer system for georeferencing a raster map, the method capable of transforming the computer system into a specific processing machine, by:

providing for display a first map and a second map, the first map being a digital raster map, and the second map being a previously georeferenced map;

the fist map being substantially similar to the second map when displayed;

receiving an entry identifying a first point pair point on the first map;

receiving an entry identifying a second point pair point on the second map, the second point pair point having approximately the same location on the second map as the first point pair point has on the first map;

assigning a point pair point on the first map a longitude coordinate and a latitude coordinate, the longitude coordinate and the latitude coordinate of the first point pair point being identical to a longitude point and a latitude point associated with a point pair point on the second map.

15. The method of

claim 14

further comprising creating the georeferencing function.

16. The method of

claim 14

further comprising receiving a mark on the first map at a location, and reproducing the mark on the second map at a corresponding location.

17. The method of

claim 14

further comprising using at least four point pairs to compute a georeferencing function for the first map based on a linear transformation, and further comprising executing a validation check.

18. The method of

claim 17

further comprising rejecting a point pair when the point pair deviates a predetermined amount from a predetermined standard error.

19. A computer readable medium whose contents enable the georeferencing of a raster map, by:

providing for display a first map and a second map, the first map being a digital raster map, and the second map being a previously georeferenced map;

the fist map being substantially similar to the second map when displayed;

receiving an entry identifying a first point pair point on the first map;

receiving an entry identifying a second point pair point on the second map, the second point pair point having approximately the same location on the second map as the first point pair point has on the first map;

assigning a point pair point on the first map a longitude coordinate and a latitude coordinate, the longitude coordinate and the latitude coordinate of the first point pair point being identical to a longitude point and a latitude point associated with a point pair point on the second map.

20. The method of

claim 19

further comprising:

using at least four point pairs to compute a georeferencing function for the first map based on a linear transformation;

further comprising executing a validation check; and

rejecting a point pair when the point pair deviates a predetermined amount from a predetermined standard error.