Method for developing and using an image reconstruction algorithm for multipath scattering
View Patent ↗Described herein is an implementation of the IRAMS processing based upon a multi-delay-resolution framework applied to SAR image data measured at different aspect angles. The power of this new embodiment of IRAMS is that it produces a good separation of immediate response scatterer and delayed response scatterer data for the case of anisotropic scattering events, i.e., those in which the scattering intensity depends upon the aspect angle. Two sources of delayed response scattering include multiple reflection scattering events and delayed responses arising from the physical material composition of the scatterer. That is, this multi-delay-resolution IRAMS processing separates immediate response and delayed response scattering for cases in which there exist delayed response scattering data in the original SAR image data at some aspect angles, but the intensity of these delayed response scattering data is weak or non-existent at different aspect angles. Thus, this IRAMS embodiment provides the additional information of the particular aspect angles at which delayed response scattering effects are most important, thereby improving both the estimates of the delayed response scattering data and the immediate response scattering data.
1. A process for estimating the contributions of single path and multipath scattering events to reflectance data in order to reconstruct an image comprising:
separating the single path events from the multipath scattering events including:
identifying N images formed at N uniformly incremented mean aspect angles;
separating the N images into N/2 pairs of adjacent first and second images,
wherein the adjacent images are separated by a time delay;
estimating the cross-range drift of direct path and multipath scattering events in progressing from the first to the second images; and
reconstructing an image utilizing the estimation of cross-range drift from the reflectance data.
2. The process according to claim 1 , wherein the direct path scattering events exhibit negligible cross-range drift between adjacent first and second images.
3. The process according to claim 1 , wherein the multipath scattering events exhibit measurable cross-range drift adjacent first and second images.
4. The process according to claim 1 , wherein the direct path scattering events are represented by single bounce reflectance data and the multipath scattering events are represented by multiple bounce reflectance data.
5. The process according to claim 1 , wherein the reflectance data is synthetic aperture radar data.
6. The process according to claim 1 , wherein the reflectance data represents two-dimensions of the image.
7. The process according to claim 1 , wherein the image is reconstructed in three dimensions.
8. The process according to claim 1 , further including collecting the reflectance data using a co-located transmitter and receiver.
9. The process according to claim 8 , wherein the reflectance data is comprised of waveforms when it is collected by the co-located transmitter and receiver.
10. The process according to claim 9 , wherein the waveforms are collected at a far-field location, such that the wavefronts impinging on a region to be imaged and collected at the receiver are approximately linear.
11. The process according to claim 9 , wherein the waveforms are collected at a near-field location, such that the wavefronts impinging on a region to be imaged and collected at the receiver are curved.
12. The process according to claim 1 , wherein the reflectance data is collected using non co-located transmitters and receivers.
13. The process according to claim 1 , wherein the reflectance data exhibits anisotropic scattering characteristics.