METHOD FOR RPC REFINEMENT USING GROUND CONTROL INFORMATION

• US 20100284629A1
• Filed: 05/06/2010
• Published: 11/11/2010
• Est. Priority Date: 05/06/2009
• Status: Active Grant

• Current Assignee: University of New Brunswick
• Original Assignee: University of New Brunswick
• Inventors: Xiong, Zhen, Zhang, Yun
• Granted Patent: US 8,542,947 B2
• Time in Patent Office: Days
• US Class Current: 382/276
• CPC Class Codes: G06T 2207/10032 Satellite or aerial image; Remote sensing
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration

Abstract

A computer implemented method of adjusting original rational polynomial coefficients of an RPC model for an image acquired by an image sensor comprising providing rational polynomial coefficients associated with the image calculating a pseudo position and attitude angles for the sensor using the original coefficients providing at least one ground control point associated with the image adjusting the pseudo position and attitude angles using the at least one ground control point; and adjusting the original coefficients for the image using the adjusted pseudo position and attitude angles.

Claims

1. A computer implemented method of adjusting original rational polynomial coefficients of an RPC model for an image acquired by an image sensor comprising:

providing rational polynomial coefficients associated with the image;

calculating a pseudo position and attitude angles for the sensor using the original coefficients;

providing at least one ground control point associated with the image;

adjusting the pseudo position and attitude angles using the at least one ground control point; and

,

adjusting the original coefficients for the image using the adjusted pseudo position and attitude angles.

2. The method of claim 1 wherein the step of calculating the pseudo position and attitude angles comprises:

calculating a pseudo sensor position and attitude angles for each ground control point.

3. The method of claim 2 wherein the step of generating an RPC model for the image comprises:

generating cubic points using the adjusted pseudo position and attitude angles.

4. The method of claim 1 further comprising:

calculating a pseudo light ray for the sensor using the coefficients where the pseudo light ray approximates a light ray existing when the image was acquired by the sensor, and

deriving the pseudo position and attitude for the sensor using the pseudo light ray where the pseudo position and attitude angles approximate the position of the sensor when the image was acquired.

5. The method of claim 4 further comprising:

selecting an image point on the image;

assigning a first elevation value to the image point;

calculating a ground position for a first ground point corresponding to the image point using the first elevation value;

assigning a second elevation value to the image point where the second elevation value is greater than the first elevation value;

calculating a ground position for a second ground point corresponding to the image point using the second elevation value;

assigning a sensor height value;

calculating a first vector from the first ground point to the second ground point using the sensor height value where the vector represents the pseudo light ray and calculating the pseudo sensor position using the first vector; and

calculating a second vector from the first vector and calculating a rotation angle in the x-direction and a rotation angle in the y-direction using the first vector and assigning a value of approximately zero to a rotation angle in the z-direction where the rotation angles represent the pseudo angles of the sensor.

6. The method of claim 5 wherein adjusting the pseudo position and attitude angles comprises calculating a linear polynomial equation.

7. The method of claim 6 wherein adjusting the original coefficients comprises calculating the ground positions for the first and second ground points comprises iterations.

8. The method of claim 7 further comprising using the adjusted coefficients for geometric correction of the image.

11. A computer software product for use on a computer system, the computer software product comprising:

a computer readable storage medium,

computer program code means stored on the computer readable storage medium, the computer program code means comprising encoded instructions that, when executed by the computer system, cause the computer system to execute steps of the method of claim 1.

9. A computer implemented method of adjusting coefficients of an RPC sensor model defining a position and attitude for a sensor comprising:

providing an image point from the image acquired by the sensor;

calculating two corresponding ground points for the image point at two different elevations;

calculating a first vector between the ground points;

calculating a position of the sensor comprising extending the first vector to a height of the sensor;

calculating a second vector using the first vector;

calculating two rotation angles using the second vector; and

adjusting the coefficients using the pseudo position and the rotation angles.

10. A computer implemented method of adjusting RPC values for an image sensor comprising:

calculating a position and an attitude in object space for the sensor from the RPC values;

providing a ground control point from an image acquired by the sensor;

calculating a pseudo sensor position and attitude in object space corresponding to the ground control point;

adjusting the sensor'"'"'s position and attitude using the pseudo position and attitude; and

adjusting the RPC values using the adjusted sensor position and attitude.