System and method for georeferencing maps
First Claim
1. A computer-implemented method of georeferencing an initially non-georeferenced raster map image, comprising the steps of:
- displaying a raster map and a georeferenced map that both depict substantially the same geographic area;
identifying three non-collinear point-pairs, each point-pair comprising one point on the raster map and one point on the georeferenced map, and each point of a point-pair lying on the same geographic feature on both maps;
using image coordinates of each point on the raster map and geographic coordinates of each corresponding point on the georeferenced map to determine functional relationships between the image coordinates and the geographic coordinates,wherein the functional relationships between the image coordinates and the geographic coordinates of the point-pairs are calculated by selecting, from a family of parametric equations and according to a general linear transform, an equation that introduces a smallest error between actual and predicted values of longitude and latitude that are assigned to the image coordinates of the raster map; and
thereafter, for each additional corresponding point-pair that is identified, revising the functional relationships between the image coordinates and the geographic coordinates according to the additional point-pairs, and disregarding any point-pairs that are substantially inconsistent with the functional relationships.
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Accused Products
Abstract
After FEMA paper flood maps are scanned into a computer system, they are each displayed side-by-side with the relevant portion of a stored vector map covering the geographic area covered by all of the FEMA maps. During display, corresponding points, or “point-pairs,” on each map are marked by a keyboard or mouse device. The corresponding points may be such artifacts as roads, stream beds, railroad tracks, intersections of the foregoing, buildings, mountain peaks, etc., which are identifiable on each displayed map. When two point-pairs are marked, a stored algorithm calculates georeferencing functions which permit translation of the x,y coordinates of the raster map to the latitude,longitude coordinates of the vector map and vice versa. As more point-pairs are marked, the georeferencing functions are refined. Another algorithm removes apparent “bad” points from the georeferencing calculations, which points may re later used if it appears that they are not bad.
168 Citations
44 Claims
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1. A computer-implemented method of georeferencing an initially non-georeferenced raster map image, comprising the steps of:
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displaying a raster map and a georeferenced map that both depict substantially the same geographic area; identifying three non-collinear point-pairs, each point-pair comprising one point on the raster map and one point on the georeferenced map, and each point of a point-pair lying on the same geographic feature on both maps; using image coordinates of each point on the raster map and geographic coordinates of each corresponding point on the georeferenced map to determine functional relationships between the image coordinates and the geographic coordinates, wherein the functional relationships between the image coordinates and the geographic coordinates of the point-pairs are calculated by selecting, from a family of parametric equations and according to a general linear transform, an equation that introduces a smallest error between actual and predicted values of longitude and latitude that are assigned to the image coordinates of the raster map; and thereafter, for each additional corresponding point-pair that is identified, revising the functional relationships between the image coordinates and the geographic coordinates according to the additional point-pairs, and disregarding any point-pairs that are substantially inconsistent with the functional relationships. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A computer-implemented method of georeferencing an initially non-georeferenced raster map image, comprising the steps of:
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displaying a raster map and a georeferenced map that both depict substantially the same geographic area; identifying two point-pairs, each point-pair comprising one point on the raster map and one point on the georeferenced map, and each point of a point-pair lying on the same geographic feature on both maps; using image coordinates of each point on the raster map and geographic coordinates of each corresponding point on the georeferenced map to determine functional relationships between the image coordinates and the geographic coordinates, wherein the functional relationships between the image coordinates and the geographic coordinates of the point-pairs are calculated by selecting, from a family of parametric equations and according to a rotational linear transform, an equation that introduces a smallest error between actual and predicted values of longitude and latitude that are assigned to the image coordinates of the raster map; and thereafter, for each additional corresponding point-pair that is identified, revising the functional relationships between the image coordinates and the geographic coordinates according to the additional point-pairs, and disregarding any point-pairs that are substantially inconsistent with the functional relationships. - View Dependent Claims (14, 15, 16, 17)
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18. A computer-implemented method of georeferencing an initially non-georeferenced raster map image, comprising the steps of:
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displaying a raster map and a georeferenced map that both depict substantially the same geographic area; identifying at least two non-collinear point-pairs, each point-pair comprising one point on the raster map and one point on the georeferenced map, and each point of a point-pair lying on the same geographic feature on both maps; using image coordinates of each point on the raster map and geographic coordinates of each corresponding point on the georeferenced map to determine functional relationships between the image coordinates and the geographic coordinates, wherein the functional relationships between the image coordinates and the geographic coordinates of the point-pairs are calculated by selecting, from a family of parametric equations and according to a rotational linear transform, an equation that introduces a smallest error between actual and predicted values of longitude and latitude that are assigned to the image coordinates of the raster map; and thereafter, for each additional corresponding point-pair that is identified, revising the functional relationships between the image coordinates and the geographic coordinates according to the additional point-pairs, and disregarding any point-pairs that are substantially inconsistent with the functional relationships. - View Dependent Claims (19, 20, 21, 22)
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23. A computer system for georeferencing an initially non-georeferenced raster map image, comprising:
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a monitor for displaying a raster map and a georeferenced map that both depict substantially the same geographic area; a first facility for identifying three non-collinear point-pairs, each point-pair comprising one point on the raster map and one point on the georeferenced map, and each point of a point-pair lying on the same geographic feature on both maps; a second facility that use raster image coordinates of each point on the raster map and the geographic coordinates of each corresponding point on the georeferenced map to determine functional relationships between the raster image coordinates and the geographic coordinates, wherein the second facility calculates the functional relationships between the raster image coordinates and the geographic coordinates of the point-pairs by selecting, from a family of parametric equations and according to a general linear transform, an equation that introduces a smallest error between actual and predicted values of longitude and latitude that are assigned to the raster image coordinates of the raster map; and a third facility for, after each additional corresponding point-pair is identified, revising the functional relationships between the raster image coordinates and the geographic coordinates according to the additional point-pairs, and disregarding any point-pairs that are substantially inconsistent with the functional relationships. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A computer system for georeferencing an initially non-georeferenced raster map image, comprising:
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a monitor for displaying a raster map and a georeferenced map that both depict substantially the same geographic area; a first facility for identifying two point-pairs, each point-pair comprising one point on the raster map and one point on the georeferenced map, and each point of a point-pair lying on the same geographic feature on both maps; a second facility that use raster image coordinates of each point on the raster map and the geographic coordinates of each corresponding point on the georeferenced map to determine functional relationships between the raster image coordinates and the geographic coordinates, wherein the second facility calculates the functional relationships between the raster image coordinates and the geographic coordinates of the point-pairs by selecting, from a family of parametric equations and according to a rotational linear transform, an equation that introduces a smallest error between actual and predicted values of longitude and latitude that are assigned to the raster image coordinates of the raster map; and a third facility for, after each additional corresponding point-pair is identified, revising the functional relationships between the raster image coordinates and the geographic coordinates according to the additional point-pairs, and disregarding any point-pairs that are substantially inconsistent with the functional relationships. - View Dependent Claims (36, 37, 38, 39)
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40. A computer system for georeferencing an initially non-georeferenced raster map image, comprising:
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a monitor for displaying a raster map and a georeferenced map that both depict substantially the same geographic area; a first facility for identifying two non-collinear point-pairs, each point-pair comprising one point on the raster map and one point on the georeferenced map, and each point of a point-pair lying on the same geographic feature on both maps; a second facility that use raster image coordinates of each point on the raster map and the geographic coordinates of each corresponding point on the georeferenced map to determine functional relationships between the raster image coordinates and the geographic coordinates, wherein the second facility calculates the functional relationships between the raster image coordinates and the geographic coordinates of the point-pairs by selecting, from a family of parametric equations and according to a rotational linear transform, an equation that introduces a smallest error between actual and predicted values of longitude and latitude that are assigned to the raster image coordinates of the raster map; and a third facility for, after each additional corresponding point-pair is identified, revising the functional relationships between the raster image coordinates and the geographic coordinates according to the additional point-pairs, and disregarding any point-pairs that are substantially inconsistent with the functional relationships. - View Dependent Claims (41, 42, 43, 44)
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Specification