Method and system for surface wear inspection using millimeter wave radar

A system comprising:

• at least one memory storing programmed instructions;
• one or more Input/Output (I/O) interfaces;
• and one or more hardware processors operatively coupled to the at least one memory, wherein the one or more hardware processors are configured by the programmed instructions to;
• receive a plurality of uncompressed raw Synthetic Aperture Radar (SAR) images pertaining to a surface under test, wherein the plurality of uncompressed raw SAR images comprises a first plurality of raw SAR images captured sequentially from a plurality of vantage points in a single pass and a second plurality of raw SAR images captured sequentially from the plurality of vantage points in a repeat pass;
• generate a plurality of reconstructed SAR images based on the plurality of uncompressed raw SAR images using a variable focusing based Range Doppler Algorithm (RDA);
• and
• examine each of the plurality of reconstructed SAR images by iteratively performing:
• selecting a master image from a first plurality of reconstructed SAR images and a slave image from a second plurality of reconstructed SAR images, from among the plurality of reconstructed SAR images;
• assigning a plurality of anchor points for the master image and a plurality of anchor points for the slave image, using a signal processing technique, wherein the plurality of anchor points are generated using a spread function;
• computing a plurality of coarse level shift coordinates based on a difference between the plurality of anchor points corresponding to the master image and the plurality of anchor points corresponding to the slave image;
• generating a plurality of pixel groups for the master image and a plurality of pixel groups for the slave image by extracting a pixel group surrounding each of the plurality of anchor points corresponding to the master image and the slave image using a pixel extraction technique;
• generating a frequency domain representation of the plurality of pixel groups for the master image and a frequency domain representation of the plurality of pixel groups of the slave image by computing a 2D Fast Fourier Transform (FFT) on the corresponding plurality of pixel groups;
• obtaining a plurality of over-sampled pixel groups for the master image and a plurality of over-sampled pixel groups for the slave image based on the corresponding frequency domain representation using zero padding;
• generating a spatial domain representation of the plurality of over-sampled pixel groups for the master image and a spatial domain representation of the plurality of over-sampled pixel groups for the slave image by computing an Inverse FFT (IFFT) on the plurality of over-sampled pixel groups corresponding to the master image and the slave image;
• identifying a deformation information associated with each of the plurality of pixel groups for the master image and a deformation information associated with each of the plurality of pixel groups for the slave image based on the corresponding spatial domain representation using a spatial data analysis technique;
• identifying a target pixel group for the master image and a target pixel group for the slave image based on the corresponding deformation information, wherein the pixel group having maximum deformation information is selected as the target pixel group;
• computing a plurality of fine level shift coordinates between the master image and the slave image based on a corresponding 2D cross-correlated target pixel groups using a sub-pixel level spatial shift computation technique;
• estimating a net shift value based on the plurality of coarse level shift coordinates and the plurality of fine level shift coordinates using a statistical technique, wherein the master image and the slave image are aligned using the net shift value;
• generating an interferogram based on the master image and a complex conjugate of the slave image using an interferogram generation technique;
• and
• profiling a deformation pertaining to the surface under test based on color variations in the interferogram using an interferogram interpretation technique.

One or more non-transitory machine-readable information storage mediums comprising one or more instructions which when executed by one or more hardware processors cause:

• receiving, a plurality of uncompressed raw Synthetic Aperture Radar (SAR) images pertaining to a surface under test, wherein the plurality of uncompressed raw SAR images comprises a first plurality of raw SAR images captured sequentially from a plurality of vantage points in a single pass and a second plurality of raw SAR images captured sequentially from the plurality of vantage points in a repeat pass;
• generating a plurality of reconstructed SAR images based on the plurality of uncompressed raw SAR images using a variable focusing based Range Doppler Algorithm (RDA);
• and
• examining each of the plurality of reconstructed SAR images by iteratively performing:
• selecting a master image from a first plurality of reconstructed SAR images and a slave image from a second plurality of reconstructed SAR images, from among the plurality of reconstructed SAR images;
• assigning a plurality of anchor points for the master image and a plurality of anchor points for the slave image, using a signal processing technique, wherein the plurality of anchor points are generated using a spread function;
• computing a plurality of coarse level shift coordinates based on a difference between the plurality of anchor points corresponding to the master image and the plurality of anchor points corresponding to the slave image;
• generating a plurality of pixel groups for the master image and a plurality of pixel groups for the slave image by extracting a pixel group surrounding each of the plurality of anchor points corresponding to the master image and the slave image using a pixel extraction technique;
• generating a frequency domain representation of the plurality of pixel groups for the master image and a frequency domain representation of the plurality of pixel groups of the slave image by computing a 2D Fast Fourier Transform (FFT) on the corresponding plurality of pixel groups;
• obtaining a plurality of over-sampled pixel groups for the master image and a plurality of over-sampled pixel groups for the slave image based on the corresponding frequency domain representation using zero padding;
• generating a spatial domain representation of the plurality of over-sampled pixel groups for the master image and a spatial domain representation of the plurality of over-sampled pixel groups for the slave image by computing an Inverse FFT (IFFT) on the plurality of over-sampled pixel groups corresponding to the master image and the slave image;
• identifying a deformation information associated with each of the plurality of pixel groups for the master image and a deformation information associated with each of the plurality of pixel groups for the slave image based on the corresponding spatial domain representation using a spatial data analysis technique;
• identifying a target pixel group for the master image and a target pixel group for the slave image based on the corresponding deformation information, wherein the pixel group having maximum deformation information is selected as the target pixel group;
• computing a plurality of fine level shift coordinates between the master image and the slave image based on a corresponding 2D cross-correlated target pixel groups using a sub-pixel level spatial shift computation technique;
• estimating a net shift value based on the plurality of coarse level shift coordinates and the plurality of fine level shift coordinates using a statistical technique, wherein the master image and the slave image are aligned using the net shift value;
• generating an interferogram based on the master image and a complex conjugate of the slave image using an interferogram generation technique;
• and
• profiling a deformation pertaining to the surface under test based on color variations in the interferogram using an interferogram interpretation technique.