System and method for georeferencing digital raster maps with resistance to potential errors

A method for georeferencing a raster map, comprising:

• displaying a first map and a second map, the first map being a digital raster map, having a plurality of pixel locations, and the second map being a previously georeferenced map, having associated geographic coordinates, wherein the first map displays at least a portion of an identical geographic region displayed in the second map, each pixel location includes an associated x-coordinate and y-coordinate, and each geographic coordinate includes an associated longitude coordinate and an associated latitude coordinate;
• receiving an entry identifying a first point pair, wherein a first pixel location on the first map is associated with a first geographic coordinate on the second map and the first pixel location is located at a position on the first map corresponding to the first geographic coordinate on the second map;
• receiving an entry identifying a second point pair, wherein a second pixel location on the first map is associated with a second geographic coordinate on the second map and the second pixel location is located at a position on the first map corresponding to the second geographic coordinate on the second map;
• assigning to the first pixel location the longitude coordinate and the latitude coordinate associated with the first geographic coordinate;
• assigning to the second pixel location the longitude coordinate and the latitude coordinate associated with the second geographic coordinate;
• creating a mathematical georeferencing function, based on the first point pair, the second point pair, a third point pair, and a fourth point pair, for assigning corresponding geographic coordinates to any one of the plurality of pixel locations, wherein the mathematical georeferencing function is based on a linear transformation;
• executing a validation check;
• and
• revising the mathematical georeferencing function when a new point pair is received.

An apparatus for georeferencing a raster map, the apparatus comprising:

• means for displaying a first map and a second map, the first map being a digital raster map, having a plurality of pixel locations, and the second map being a previously georeferenced map, having associated geographic coordinates, wherein the first map displays at least a portion of an identical geographic region displayed in the second map, each pixel location includes an associated x-coordinate and y-coordinate, and each geographic coordinate includes an associated longitude coordinate and an associated latitude coordinate;
• means for receiving an entry identifying a first point pair, wherein a first pixel location on the first map is associated with a first geographic coordinate on the second map and the first pixel location is located at a position on the first map corresponding to the first geographic coordinate on the second map;
• means for receiving an entry identifying a second point pair, wherein a second pixel location on the first map is associated with a second geographic coordinate on the second map and the second pixel location is located at a position on the first map corresponding to the second geographic coordinate on the second map;
• means for assigning to the first pixel location the longitude coordinate and the latitude coordinate associated with the first geographic coordinate;
• means for assigning to the second pixel location the longitude coordinate and the latitude coordinate associated with the second geographic coordinate;
• means for creating a mathematical georeferencing function, based on the first point pair, the second point pair, a third point pair, and a fourth point pair, to assign corresponding geographic coordinates to any one of the plurality of pixel locations, wherein the mathematical for georeferencing function is based on a linear transformation;
• executing a validation check;
• and
• means for revising the mathematical georeferencing function when a new point pair is received.

A computer readable medium containing instructions executable by a computer to perform a method to georeference a raster map, the method comprising:

• displaying a first map and a second map, the first map being a digital raster map, having a plurality of pixel locations, and the second map being a previously georeferenced map, having associated geographic coordinates, wherein the first map displays at least a portion of an identical geographic region displayed in the second map, each pixel location includes an associated x-coordinate and y-coordinate, and each geographic coordinate includes an associated longitude coordinate and an associated latitude coordinate;
• receiving an entry identifying a first point pair, wherein a first pixel location on the first map is associated with a first geographic coordinate on the second map and the first pixel location is located at a position on the first map corresponding to the first geographic coordinate on the second map;
• receiving an entry identifying a second point pair, wherein a second pixel location on the first map is associated with a second geographic coordinate on the second map and the second pixel location is located at a position on the first map corresponding to the second geographic coordinate on the second map;
• assigning to the first pixel location the longitude coordinate and the latitude coordinate associated with the first geographic coordinate;
• assigning to the second pixel location the longitude coordinate and the latitude coordinate associated with the second geographic coordinate;
• creating a mathematical georeferencing function, based on the first point pair, the second point pair, a third point pair, and a fourth point pair, for assigning corresponding geographic coordinates to any one of the plurality of pixel locations, wherein the mathematical georeferencing function is based on a linear transformation;
• executing a validation check;
• rejecting one of the point pairs when an error associated with the one point pair deviates a predetermined amount from a standard error computed using the other point pairs;
• and
• revising the mathematical georeferencing function when a new point pair is received.