Limited region question

[Godstrike]

I have a scene where when I render the entire frame I get 2.4 or so Ms.Sec, but when I render just a tiny portion of it with limited region I get 1.23 Ms.Sec

Aren't the render times for limited region supposed to be faster than rendering the entire frame, otherwise what would the point be? I might as well just render the entire frame.

With other unbiased render engines there is an appreciable increase in speed when only rendering a small section with render region, or does this not hold true for GPU rendering.

© --

[Godstrike]

Follow up to this, even though the Ms.Sec are less and I did not render anywhere close to the same number of samples (less than half the full frame version), the limited region render is more cleanly resolved.

What is going on here?

[Godstrike]

OK, I'm answering my own question here, but I suppose the total number of pixels is so much smaller that even a lower Ms.Sec count yields far more results...or something~?

[juanjgon]

I am not sure, perhaps the statistics using the limited region are not working fine, but as you can see the region is cleaning a lot faster so I think that this feature works fine.

-Juanjo

[MrFurious]

Maybe there's more intricate detail in the region you selected. IE, try selecting a single flat surface or a sky, then select another region such as a tree with thousands of polys I noticed this effects the sample rate dramatically in RRegion.

But yes there are issues with render region, another one which I discovered recently but will post in the original thread on this subject which is located here:

http://render.otoy.com/forum/viewtopic.php?f=36&t=41794

[Godstrike]

MrFurious: Copy that, will give that a try.

Juan: Yes, it's definitely resolving a lot cleaner faster. Another issue is that the samples at, say 1000 look a lot cleaner on the small render than 1000 samples on the large render. It makes matching pick-up shots tough when you can't render to exactly the same quality level in a predictable way.