Noisy Portals

[YAFU (English is not my native language)]

Portals stopped being very useful since the default settings of Multiple Importance Sampling changed in Blender:

Blender 2.8 Cycles rendering with portals

Just trying to understand why when Portals was implemented in 2.75, nobody doubted the advantages of this with respect to the lower noise (no lower render time). The advantage of Portals was clear in many user tests, obtaining much less noise. But then in new versions of Blender some users began to question the advantages of Portals in some interior scenes. The think is that in 2.75 default scenes were set in World tab by default: Settings > Multiple Importance=OFF (Map Resolution=256 if you en…

You will notice the noise reduction mainly when Multiple Importance Sampling=OFF (World tab > Settings > Surface > Sampling=None), or with low Map Resolution values.
And less noise reduction doesn’t always mean less render times with portals. Actually, nowadays I’m not sure if portals is useful.