Interior problem

Carlos, do forgive my ignorance. its seems that i couldn't find the light cache parameters. I do try to up my interpolation, and the result is quite satisfying. Thanks

ok, thanks sanchez

there are two ways of fixing this. up your HSph subdivs to 100 and your preset to medium, light cache to 1000. this would be a good starting point. the other way around this at the cost of detail in the shading of the corners is to leave your HSph subdivs at 50 and up the interpolation samples. this will make your Irradiance map much smother but with less detail.

It might be your render quality. It's called "noise". Up your render settings some.