  Until now, despite their high accuracy, the utilization of the conventional
image theory method ray tracers was limited to simple simulation environments
with small number of field observation points and low maximum ray bouncing
order due to their poor computational efficiency. This study presents a novel
full-3D AZB rectangle shrinkage method and heterogeneous computing accelerated
image theory method ray tracing framework for complex and massive outdoor
propagation modeling. The proposed framework is divided into three parts: 1.
Visibility preprocessing part. 2. Visibility tree generation part: in this
part, a novel AZB rectangle shrinkage method that accelerates and reduces
generation speed and size of visibility tree is proposed. 3. Shadow testing and
field calculation part: in this part, a heterogeneous computing algorithm that
can make possible to handle a large amount of field observation points is
proposed. It is demonstrated that the proposed framework is faster more than
651 times than the image theory method solver of WinProp. Also, it is confirmed
that the proposed ray tracing framework can handle 1km x 1km wide and dense
urban outdoor simulation with up to the maximum ray bouncing order of 6 and
thousands of field observation points. The proposed ray tracing framework would
be a cornerstone of future image theory method ray tracing techniques for
complex and massive scenarios that was exclusive to the shooting and bouncing
rays method ray tracers.
