Processor: Intel(R) Core i5-8400 CPU @2.8GHz
RAM: 16x2 GB DDR4 3002Mhz
Graphics Card: GTX1080 Ti
OS: Windows 10 Education x64
IDE: Visual Studio 2017 Enterpise
I delete the top floor so eliminate the reclection of top floor so that pure path tracing won't get caustics
Rendered Result, 16 x 16 ssp, global + indirect photonmap
Rendered Result, 16 x 16 ssp, indirect only photonmap