Shortest path ray tracing in cell model with a second-level forward star

Abstract

SUMMARY The high-level forward star is routinely applied in seismic ray tracing using graph theory (sometimes referred to as the shortest path method) with a grid model. For a cell model, the forward star is often restricted to nodes at the same cell (i.e. first-level forward star). The performance of a cell model with second-level forward stars is found to be comparable in both computation time and accuracy to that of a doubly dense cell model with first-level forward stars. Moreover, the cell model with second-level forward stars has the advantage of halving the required computer storage. An optimization of the secondary node geometry leads to a further 20 per cent improvement in accuracy. Concepts derived from grid models for analytical error estimation are found to be less applicable to cell models. An empirical approach works better in the optimization of the secondary node geometry.