A graph-space approach to optimal transport for full-waveform inversion
Résumé
Optimal transport distances have been recently proposed to design more convex misfit functions in the frame of full waveform inversion. The main difficulty for this strategy is the non-positivity of seismic data: the optimal transport is developed for the comparison of positive quantities. We review the proposed strategies to overcome this difficulty and put in light their limitations: in particular, those applicable to field data lose the convexity property. On this basis, we propose an alternative approach, consisting in measuring the optimal transport distance between the discrete graph of seismic traces. This makes possible to apply optimal transport to real seismic data, while preserving the convexity. Two synthetic case studies illustrate the interest of the method. The main drawback is related to the computational cost of the current implementation: more powerful techniques based on this idea will soon be investigated.