Abstract: A method for simulating interactions between a propagating field and occluding bodies in a volume is provided. The method includes using a processor to construct a three-dimensional grid structure having a plurality of cells, the volume containing a plurality of two-dimensional triangles that intersect or reside in one or more of the cells; to iterate through a plurality of rays and trace each ray of the plurality to approximate the propagating field; to determine and account for all interactions between each ray of the plurality and the occluding bodies, where the determining includes performing ray-triangle intersection for all triangles of the plurality of triangles intersecting or residing in cells occupied by the occluding bodies, and the accounting includes adding additional rays of the plurality of rays as reflections, transmissions, and diffractions of the approximated propagating field.