Damage proxy map from interferometric synthetic aperture radar coherence
A method, apparatus, and article of manufacture provide the ability to generate a damage proxy map. A master coherence map and a slave coherence map, for an area prior and subsequent to (including) a damage event are obtained. The slave coherence map is registered to the master coherence map. Pixel values of the slave coherence map are modified using histogram matching to provide a first histogram of the master coherence map that exactly matches a second histogram of the slave coherence map. A coherence difference between the slave coherence map and the master coherence map is computed to produce a damage proxy map. The damage proxy map is displayed with the coherence difference displayed in a visually distinguishable manner.
1. A computer-implemented method for generating a damage proxy map, comprising:
receiving first radar signals for an area prior to a damage event;
obtaining, based on the first radar signals, a master coherence map for the area prior to the damage event;
receiving second radar signals for the area spanning the damage event;
obtaining, based on the second radar signals, a slave coherence map for the area including the damage event;
registering the slave coherence map to the master coherence map;
modifying pixel values of the slave coherence map using histogram matching, wherein a first histogram of the master coherence map exactly matches a second histogram of the slave coherence map;
computing a coherence difference between the modified slave coherence map and the master coherence map to produce a damage proxy map; and
displaying the damage proxy map, wherein the coherence difference is displayed in a visually distinguishable manner.
2. The method of claim 1 , wherein the master coherence map and slave coherence map are obtained from an interferometric synthetic aperture radar (InSAR) without ground truth validation.
3. The method of claim 1 , wherein:
the master coherence map comprises a first pair of interferometric coherence maps;
the slave coherence map comprises a second pair of interferometric coherence maps; and
three (3) InSAR images are used to create the first pair and the second pair of interferometric coherence maps.
4. The method of claim 1 , wherein the slave coherence map is registered to the master coherence map using cross-correlation of amplitude images.
5. The method of claim 1 , further comprising performing unbiased time series analysis of coherence change.
6. The method of claim 1 , further comprising:
suppressing background clutter by applying a causality constraint to the damage proxy map.
7. The method of claim 1 , further comprising:
transforming the damage proxy map onto a georeferenced coordinate system; and
overlaying the transformed damage proxy map onto a map/geographic information program based on the georeferenced coordinate system.
8. The method of claim 1 , further comprising:
assessing and performing emergency rescue operations based on the damage proxy map.
9. An apparatus for generating a damage proxy map in a computer system comprising:
(a) a computer having a memory; and
(b) an application executing on the computer, wherein the application is configured to:
(1) receive first radar signals for an area prior to a damage event;
(2) obtain, based on the first radar signals, a master coherence map for the area prior to the damage event;
(3) receive second radar signals for the area spanning the damage event;
(4) obtain, based on the second radar signals, a slave coherence map for the area including the damage event;
(5) register the slave coherence map to the master coherence map;
(6) modify pixel values of the slave coherence map using histogram matching, wherein a first histogram of the master coherence map exactly matches a second histogram of the slave coherence map;
(7) compute a coherence difference between the modified slave coherence map and the master coherence map to produce a damage proxy map; and
(8) display the damage proxy map, wherein the coherence difference is displayed in a visually distinguishable manner.
10. The apparatus of claim 9 , wherein the master coherence map and slave coherence map are obtained from an interferometric synthetic aperture radar (InSAR) without ground truth validation.
11. The apparatus of claim 9 , wherein:
the master coherence map comprises a first pair of interferometric coherence maps;
the slave coherence map comprises a second pair of interferometric coherence maps; and
three (3) InSAR images are used to create the first pair and the second pair of interferometric coherence maps.
12. The apparatus of claim 9 , wherein the slave coherence map is registered to the master coherence map using cross-correlation of amplitude images.
13. The apparatus of claim 9 , wherein the application is further configured to perform unbiased time series analysis of coherence change.
14. The apparatus of claim 9 , wherein the application is further configured to suppress background clutter by applying a causality constraint to the damage proxy map.
15. The apparatus of claim 9 , wherein the application is further configured to:
transform the damage proxy map onto a georeferenced coordinate system; and
overlay the transformed damage proxy map onto a map/geographic information program based on the georeferenced coordinate system.
16. The apparatus of claim 9 , wherein the application is further configured to:
provide an assessment of emergency rescue operations based on the damage proxy map.