Superpixel edges for boundary detection

• US 9,389,311 B1
• Filed: 10/29/2015
• Issued: 07/12/2016
• Est. Priority Date: 02/19/2015
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Moya, Mary M., Koch, Mark W.
• Primary Examiner(s): Sotomayor, John B
• Application Number:
  US14/927,066
• Time in Patent Office: 257 Days
• Field of Search: 342 25 A- 25 F, 342/191, 342/195
• US Class Current: 1/1
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
• CPC Class Codes: G01S 13/9023 combined with interferometric techniques
• CPC Class Codes: G06T 2207/10044 Radar image
• CPC Class Codes: G06T 2207/30181 Earth observation
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06V 20/13 Satellite images

Abstract

Various embodiments presented herein relate to identifying one or more edges in a synthetic aperture radar (SAR) image comprising a plurality of superpixels. Superpixels sharing an edge (or boundary) can be identified and one or more properties of the shared superpixels can be compared to determine whether the superpixels form the same or two different features. Where the superpixels form the same feature the edge is identified as an internal edge. Where the superpixels form two different features, the edge is identified as an external edge. Based upon classification of the superpixels, the external edge can be further determined to form part of a roof, wall, etc. The superpixels can be formed from a speckle-reduced SAR image product formed from a registered stack of SAR images, which is further segmented into a plurality of superpixels. The edge identification process is applied to the SAR image comprising the superpixels and edges.

Claims

1. A computing system comprising:

a processor; and

memory that comprises instructions that, when executed by the processor, cause the processor to perform acts comprising;

comparing a first property of a first superpixel assigned to a first pixel in a first radar image and a second property of a second superpixel assigned to the first pixel in the first radar image, wherein the first pixel is included in a first edge of the first superpixel; and

in response to determining the first property and the second property are similar, identifying the first superpixel and the second superpixel as having similar radar-reflecting properties and labeling the first edge as an internal edge;

or

in response to determining the first property and the second property are dissimilar, identifying the first superpixel and the second superpixel as having contrasting radar-reflecting properties and labeling the first edge as an external edge.

2. The computing system of claim 1, wherein the first property is a contrast measure and the second property is a contrast measure.

3. The computing system of claim 1, wherein the first radar image is a synthetic aperture radar image.

4. The computing system of claim 1, wherein the determining that the first property and the second property are similar further comprising determining a contrast measure between the first property and the second property is below a threshold value.

5. The computing system of claim 1, wherein the determining that the first property and the second property are dissimilar further comprising the determining a contrast measure between the first property and the second property is above a threshold value.

6. The computing system of claim 1, the acts further comprising:

identifying the first superpixel in the first radar image;

labeling each pixel included in the first superpixel with a first identifier of the first superpixel;

identifying the second superpixel in the first radar image; and

labeling each pixel included in the second superpixel with a second identifier of the second superpixel.

7. The computing system of claim 6, the acts further comprising:

overlaying the first radar image with a second radar image, wherein the second radar image is a copy of the first radar image, and the first radar image and the second radar image are co-aligned;

adjusting a position of the second radar image with respect to the first radar image, wherein the position of the second radar image is adjusted by one pixel width in any of an up direction, a down direction, a right direction, or a left direction;

detecting a first superpixel identifier (ID) of the first pixel in the first radar image is different to a second superpixel ID of a second pixel in the second radar image overlaid on the first pixel of the first image; and

determining, based upon the difference between the first superpixel ID of the first pixel and second superpixel ID of a second pixel, the first pixel forms part of the edge of the first superpixel and the second pixel forms part of an edge of the second superpixel.

8. The computing system of claim 6, the acts further comprising:

applying the second superpixel ID to the first pixel, enabling assignment of the first property of the first superpixel and assignment of the second property of the second superpixel to the first pixel.

9. The computing system of claim 1, wherein the radar image is generated by acts further comprising:

registering a plurality of synthetic aperture radar (SAR) images to form a stack of registered SAR images;

generating an artifact-reduced SAR image product based upon at least one registered SAR image from the stack of registered SAR images, the artifact-reduced SAR image product comprises fewer artifacts than the at least one registered SAR image; and

oversegmenting the artifact-reduced SAR image product into a plurality of superpixels to form a superpixel image product.

10. The computing system of claim 9, wherein generating the artifact-reduced SAR image product comprises performing at least one of a sub-aperture multilook (SA-ML) imaging process, a mean-over-time of coherent change detection (MCCD) imaging process, or a median-over-time of radar cross section (MRCS) imaging process to the at least one registered SAR image.

11. The computing system of claim 10, wherein the first property and second property are based in part on at least one result of the SA-ML imaging process, the MCCD imaging process, or the MRCS imaging process.

12. A method comprising:

comparing a first property of a first superpixel assigned to a first pixel in a first radar image and a second property of a second superpixel assigned to the first pixel in the first radar image, wherein the first pixel is included in a first edge of the first superpixel; and

in response to determining the first property and the second property are similar, identifying the first superpixel and the second superpixel as having similar radar-reflecting properties and labeling the first edge as an internal edge;

or

in response to determining the first property and the second property are dissimilar, identifying the first superpixel and the second superpixel as having contrasting radar-reflecting properties and labeling the first edge as an external edge.

13. The method of claim 12, wherein a contrast measure determines similarity between the first property and the second property.

14. The method of claim 12, wherein the first radar image is a synthetic aperture radar image.

15. The method of claim 12, wherein the determining that:

the first property and the second property are similar further comprising determining a contrast between the first property and the second property is below a threshold value; and

the first property and the second property are dissimilar further comprising the determining a contrast between the first property and the second property is above a threshold value.

16. The method of claim 12, further comprising:

identifying the first superpixel in the first radar image;

labeling each pixel included in the first superpixel with a first identifier of the first superpixel;

identifying the second superpixel in the first radar image; and

labeling each pixel included in the second superpixel with a second identifier of the second superpixel.

17. The method of claim 16, further comprising:

overlaying the first radar image with a second radar image, wherein the second radar image is a copy of the first radar image, and the first radar image and the second radar image are co-aligned;

adjusting a position of the second radar image with respect to the first radar image, wherein the position of the second radar image is adjusted by one pixel width in any of an up direction, a down direction, a right direction, or a left direction;

detecting a first superpixel identifier (ID) of the first pixel in the first radar image is different to a second superpixel ID of a second pixel in the second radar image overlaid on the first pixel of the first image;

determining, based upon the difference between the first superpixel ID of the first pixel and second superpixel ID of a second pixel, the first pixel forms part of the edge of the first superpixel and the second pixel forms part of an edge of the second superpixel; and

applying the second superpixel ID to the first pixel, enabling assignment of the first property of the first superpixel and assignment of the second property of the second superpixel to the first pixel.

18. A computer-readable storage medium comprising instructions that, when executed by a processor, cause the processor to perform acts comprising:

comparing a first property of a first superpixel assigned to a first pixel in a first radar image and a second property of a second superpixel assigned to the first pixel in the first radar image, wherein the first pixel is included in a first edge of the first superpixel;

determining a contrast between the first property and the second property is below a threshold value; and

in response to determining the first property and the second property are below the threshold value, identifying the first superpixel and the second superpixel as having similar radar-reflecting properties and labeling the first edge as an internal edge;

or

determining a contrast between the first property and the second property is above the threshold value; and

in response to determining the first property and the second property are above the threshold value, identifying the first superpixel and the second superpixel as having contrasting radar-reflecting properties and labeling the first edge as an external edge.

19. The computer-readable storage medium of claim 18, the acts further comprising:

identifying the first superpixel in the first radar image;

labeling each pixel included in the first superpixel with a first identifier of the first superpixel;

identifying the second superpixel in the first radar image; and

labeling each pixel included in the second superpixel with a second identifier of the second superpixel.

20. The computer-readable storage medium of claim 19, the acts further comprising:

overlaying the first radar image with a second radar image, wherein the second radar image is a copy of the first radar image, and the first radar image and the second radar image are co-aligned;

adjusting a position of the second radar image with respect to the first radar image, wherein the position of the second radar image is adjusted by one pixel width in any of an up direction, a down direction, a right direction, or a left direction;

detecting a first superpixel identifier (ID) of the first pixel in the first radar image is different to a second superpixel ID of a second pixel in the second radar image overlaid on the first pixel of the first image;

determining, based upon the difference between the first superpixel ID of the first pixel and second superpixel ID of a second pixel, the first pixel forms part of the edge of the first superpixel and the second pixel forms part of an edge of the second superpixel; and

applying the second superpixel ID to the first pixel, enabling assignment of the first property of the first superpixel and assignment of the second property of the second superpixel to the first pixel.