Guided wavefield detection is at the basis of a number of promising techniques for the identification and the characterization of damage in plate structures. Among the processing techniques proposed, the estimation of instantaneous wavenumbers can be used as an effective metric that localize and quantifies delaminations in composite plates. A process able to estimate the in-plane and out-of-plane (depth) coordinate of a feature in a 2D structure using the Frequency Domain Instantaneous Wavenumber (FDIW) damage quantification technique is detailed in this paper. A post processing algorithm using a smooth sparse decomposition is used to highlight the studied features. The effectiveness of this method combined to the post processing technique is demonstrated for both numerical and experimental cases. This proposed methodology can be considered as a first step towards a hybrid structural health monitoring/ nondestructive evaluation (SHM/NDE) approach for damage assessment in composites.