System and method for georeferencing maps

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 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.

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 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.

A computer system for georeferencing an initially non-georeferenced raster map image, comprising:

• 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.

A computer system for georeferencing an initially non-georeferenced raster map image, comprising:

• 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.

A computer system for georeferencing an initially non-georeferenced raster map image, comprising:

• 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.