Method of interest point matching for images

1. A computer implemented method for point matching comprising:

(a) providing a stereo pair of digital images;

(b) selecting a first set of interest points from a first image of the stereo pair and a second sets of interest points from a second images of the stereo pair;

(c) selecting super points from each set of interest points wherein the super points are interest points which have an interest strength greater than a specified threshold;

(d) searching for conjugate points to the super points, wherein a conjugate point comprises a point in a corresponding image of the stereo pair having an interest strength greater than the specified threshold;

(e) constructing a control network using super points for which conjugate points have been located in step (d), each such super point being called a control network point;

(f) assigning a position, with respect to the closest control network point, to interest points in each set which are not control network points;

(g) searching for conjugate points to the interest points whose position, assigned in step (f), is closest to a control network point; and

(h) adding interest points, for which a conjugate point has been located in step (g), to the control network.

2. The method of claim 1 further comprising repeating steps (f) to (g) for other points on the images.

3. The method of claim 1 wherein the conjugate points are tie points.

4. The method of claim 1 wherein in step (f) the assigning a position comprises assigning a relative position and angle relative to the closest super point.

5. A computer implemented method for point matching comprising:

(a) providing a pair of images captured;

(b) selecting first and second sets of interest points from the images;

(c) constructing a control network of super points for each set of interest points;

(d) assigning a position, with respect to the closest network control point of each control network, to other interest points on the images;

(e) locating conjugate points for each other interest point of each set based on its assigned position;

(f) adding the conjugate points to the control network, wherein the conjugate points are tie points;

selecting a first start point and a first root point from the first set wherein the other points of the first set are leaf points;

calculating a first distance between the first start point and the first root point;

selecting a second start point and a second root point from the second set wherein the second start point and the second root point are selected such that the distance between them is closest to the first distance;

and wherein assigning a position to the other points comprises:

assigning a relative position and angle to each other point (leaf point) of each network by

calculating a distance between each leaf point of the set and the root point of the set; and

calculating for each leaf point of the set, an angle from a line formed by the start point of the set and the root point of the set, to a line formed by the leaf point and the root point of the set

for each control network, grouping each interest point from a set with the closest node of the control network by:

constructing a sub-control network for each network with the closest node and the interest points grouped with the node; and,

conducting interest point matching between the two sub-control networks.

6. The method of claim 5 further comprising selecting the interest points with the smallest relative position and angle as tie points.

7. The method of claim 6 wherein the selecting of the sets of interest points comprises using a Harris algorithm.