Anisotropic model building with tomography is an underdetermined inverse problem. Simultaneously solving for P-wave velocity, epsilon, and delta is not stable when only surface seismic data is used. In this work, a model covariance function was built to constrain post-migration grid tomography using prior information from rock physics and structural dip. Quantitative uncertainty analysis was performed after tomography to measure the non-uniqueness of the problem. We present an example in the Green Canyon area of the Gulf of Mexico to demonstrate the effectiveness of the method.