Real-time composite image comparator

• US 20060028549A1
• Filed: 08/03/2005
• Published: 02/09/2006
• Est. Priority Date: 08/04/2004
• Status: Active Grant

• Current Assignee: Intergraph Software Technologies Company
• Original Assignee: Intergraph Software Technologies Company
• Inventors: Whitaker, Sheila G., Grindstaff, Gene A.
• Granted Patent: US 7,961,216 B2
• Time in Patent Office: Days
• US Class Current: 348/144
• CPC Class Codes: G01C 11/02 Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
• CPC Class Codes: G01C 11/04 Interpretation of pictures

Abstract

An apparatus and method for preparing a composite image from a video data stream and for identifying changed features in two composite images. Frames from the video data stream are transformed to a projected 2D image, aligned with adjacent frames and overlapping areas are averaged to provide a higher apparent resolution. The composite image can be stored in real-time. As a second composite image is prepared of the same location at a later time, portions of the second image can be compared to corresponding portions of the stored image after the intensities of the images are equalized. Image areas whose absolute difference exceeds a threshold are again intensity equalized. Areas that are again above threshold can be flagged for further scrutiny, either by a human or by a machine that performs object recognition. In this way, composite video images of a scene can be prepared and compared in real-time.

Claims

1. A method for preparing a first composite image of a first scene comprising:

a. providing a first series of images, each image corresponding to a portion of the first scene, at least two images containing overlapping areas in the first scene;

b. aligning the at least two images of the first scene;

c. averaging the areas of overlap of the at least two images of the first scene; and

d. forming the first composite image from the non-overlapping portions of the at least two images of the first scene and the averaged overlapping portions of the at least two images of the first scene, thereby providing a higher resolution for portions of the composite image than the resolution of the series of images.

2. A method according to claim 1 wherein providing a first series of images includes capturing a video sequence with a video camera.

3. A method according to claim 1 wherein the first scene is a terrain scene.

4. A method according to claim 1 wherein providing the first series of images includes transforming the first series of images.

5. A method according to claim 4 wherein transforming the first series of images includes projecting the first series of images onto a two-dimensional surface.

6. A method according to claim 1 wherein aligning the at least two images includes correlating portions of the at least two images.

7. A method according to claim 1 for comparing the first composite image and a second composite image of a second scene, further including:

e. storing the first composite image;

f. preparing the second composite image including;

i. providing a second series of images, each image corresponding to a portion of the second scene, at least two images containing overlapping areas in the second scene,

ii. aligning the at least two images of the second scene,

iii. averaging the areas of overlap of the at least two images of the second scene, and

iv. forming the second composite image from the non-overlapping portions of the at least two images of the second scene and the averaged overlapping portions of the at least two images of the second scene;

g. adjusting overlapping portions of the first composite image and the second composite image to approximately equal average intensity; and

h. calculating the difference between overlapping portions of the intensity adjusted images and identifying areas of the overlapping portions of the intensity adjusted images where the difference is above a threshold.

8. A method according to claim 7 wherein identifying areas of the overlapping portions of the intensity adjusted images where the difference is above a threshold begins before preparing the second composite image completes.

9. A method according to claim 7 wherein edges are removed from the composite images before calculating the difference between the images.

10. A computer program product for use on a computer system for preparing a first composite image of a first scene, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code including:

a. program code for providing a first series of images, each image corresponding to a portion of the first scene, at least two images containing overlapping areas in the first scene;

b. program code for aligning the at least two images of the first scene;

c. program code for averaging the areas of overlap of the at least two images of the first scene;

d. program code for forming the first composite image from the non-overlapping portions of the at least two images of the first scene and the averaged overlapping portions of the at least two images of the first scene, thereby providing a higher resolution for portions of the composite image than the resolution of the series of images.

11. A computer program product according to claim 10, wherein providing a first series of images includes capturing a video sequence with a video camera.

12. A computer program product according to claim 10, wherein the first scene is a terrain scene.

13. A computer program product according to claim 10, wherein program code for providing the first series of images includes program code for transforming the first series of images.

14. A computer program product according to claim 13, wherein program code for transforming the first series of images includes program code for projecting the first series of images onto a two-dimensional surface.

15. A computer program product according to claim 10, wherein program code for aligning the at least two images of the first scene includes program code for correlating portions of the at least two images.

16. A computer program product according to claim 10 for comparing the first composite image and a second composite image of a second scene, further including:

e. program code for storing the first composite image;

f. program code for preparing the second composite image including;

i. program code for providing a second series of images, each image corresponding to a portion of the second scene, at least two images containing overlapping areas in the second scene,

ii. program code for aligning the at least two images of the second scene,

iii. program code for averaging the areas of overlap of the at least two images of the second scene, and

iv. program code for forming the second composite image from the non-overlapping portions of the at least two images of the second scene and the averaged overlapping portions of the at least two images of the second scene;

g. program code for adjusting overlapping portions of the first composite image and the second composite image to approximately equal average intensity; and

h. program code for calculating the difference between the intensity adjusted images and identifying areas of the images where the difference is above a threshold.

17. A computer program product according to claim 16 wherein program code for identifying areas of the images where the difference is above a threshold is configured to execute before program code for preparing the composite image of the second image completes.

18. A computer program product according to claim 16 wherein the program code is configured so that edges are detected and removed from the composite images before calculating the difference between the images.