Hey @brenoveiga
With your file, I was able to recreate some of the lines that you are seeing between the grid subdivision:
However, they are a bit different from yours and I am pretty sure that this is because we are just seeing the stochastic behavior of Radiance’s ambient divisions here. Specifically, you are seeing a different set of randomly-generated divisions for each of the grid subdivisions because your Radiance parameters are not suited for this huge scene that is several orders of magnitude larger than the details of the floor you are studying.
So it seems that your large scene and your custom Radiance parameters are largely to blame here.
Unless you really know what each and every radiance parameter does, I would recommend not trying to change all of them like this:
There’s a good reason why we included the HB Radiance Parameter component to give you recommendations because even the most advanced Radiance gurus usually don’t know what all of them do.
Also, there’s a lot to be said about just simulating the things that you care about and not dumping hundreds of thousands of polygons into your Radiance model just because you can.