Using ray tracing (2/2) HB n=] 2 h R h Since diffraction is a very time-consuming interaction,and up to 10 or more diffractions are required for ORT paths,then often ORT propagation is treated off-line using a multi-diffraction ORT model even if the RT model is 3D Then multi-diffraction ORT is considered as one single interaction in the RT engine and in the view tree,so that it can be combined with other interactions even with Nev is low Rays experiencing"ORT+scattering"or"ORT+reflected"are very important for time and angle dispersion 3 3 • Since diffraction is a very time-consuming interaction, and up to 10 or more diffractions are required for ORT paths, then often ORT propagation is treated off-line using a multi-diffraction ORT model even if the RT model is 3D • Then multi-diffraction ORT is considered as one single interaction in the RT engine and in the view tree, so that it can be combined with other interactions even with Nev is low • Rays experiencing “ORT+scattering” or “ORT+reflected” are very important for time and angle dispersion Using ray tracing (2/2) r1 r0 h0 h R 1 n=1 2 M HB