The NASA-ISRO Synthetic Aperture Radar (NISAR) Range Doppler Wrapped Interferogram (RIFG) product represents the ellipsoid and topography flattened wrapped interferogram generated from two Level 1 Range-Doppler Single Look Complex (RSLC) products in the range-Doppler geometry of the earlier reference acquisition. The WGS84 ellipsoid is used as the reference surface for flat earth correction.

The RIFG product contains a binary raster layer of complex numbers, i.e., the wrapped interferogram; its phase represents the wrapped interferometric phase in radians. The product also contains a binary raster layer of floating-point numbers representing the normalized interferometric correlation, i.e., the interferometric coherence magnitude. The wrapped interferogram and the interferometric coherence magnitude are multi-looked to a nominal posting of 30 m on the ground. No ionospheric phase screen correction layers are available with this product.

The interferometric workflow producing RIFG products coregisters a pair of RSLC products using a Digital Elevation Model and the best available orbit ephemeris. This coregistration is refined using incoherent cross-correlation on the pair of coarsely coregistered RSLCs. The RIFG product includes the slant range and along-track sub-pixel offsets obtained from incoherent cross-correlation and used to generate the complex wrapped interferogram. If a Range Doppler Pixel Offsets (ROFF) product is available for the processed frame, the sub-pixel offset layers included in RIFG are obtained by optimally blending the multi-resolution offset layers included in ROFF.