glossy refs faster than sharp?

[super gnu]

i cant imagine why. ive got a scene with a pure reflective mirror, and the noise in the reflection takes quite a long time to clear.. strangely i found that turning the reflection glossiness from 1 to 0.99 actually rendered faster, and gave a less noisy result at the end...?

only shaved a few seconds off the time, but its a counter-intuitive result for me.

im using RT gpu.

[savage309]

Well, it depends on what has been reflected in that mirror, I guess. Usually, making it glossy will be harder to compute, but I guess a specific scenarious can have (small) difference in the other direction.

Best,
Blago.

[thanulee]

I think, very sharp reflections, need more AA samples cause its harder the contrast between the pixels. Ofc visible difference between .99 and 1.0 is not exactly there, unless u lower the GGX amount to something around 1.5-1.2 (i think ggx doesnt work in 1.0 reflections)
Therefore might be the reason for faster rendertimes? In anyway, this is good news, cause its always better to lower the complete sharp reflections a bit.

[^Lele^]

I think, very sharp reflections, need more AA samples cause its harder the contrast between the pixels. Ofc visible difference between .99 and 1.0 is not exactly there, unless u lower the GGX amount to something around 1.5-1.2 (i think ggx doesnt work in 1.0 reflections)
Therefore might be the reason for faster rendertimes? In anyway, this is good news, cause its always better to lower the complete sharp reflections a bit.

indeed, adding glossiness redistributes the incoming energy over a broader area, lowering local contrast, and so -especially with visible, bright light sources- potentially require fewer AA samples at the edges than a sharp, or semi-sharp reflection boundary would.