There are two different simulation methods used in Radiance IES:
· rtrace is a radiance calculation that uses ray-tracing every time step. It is computationally expensive and not generally used for simulations that require calculation at every timestep (dynamic).
· rcontrib is a radiance calculation that performs one higher quality ray-tracing calculation to create daylight coefficients for sensor or grid points. The coefficients are then used to calculate illuminance at each time step. This method is used for CBDM simulations (UDI sDA and ASE).
· rtrace_dc, a “daylight coefficient” method of ray tracing which allows or faster methods of calculation of illuminance. This is used for CBDM simulations and is on by default.
