Digital ray tracing for geotomography

Two methods for determining the coefficients in R, each element of which represents the transit length of the ith arc over the jth cell, are examined. The first method calculates the exact distance traveled by the ith ray over the jth cell, rij. For situations in which only a 0 or 1 indication of whether a cell is touched by a ray is required, a digital ray tracing method is considered. The quality of the images and the speed of the algorithms are discussed