basicwiz opened this issue on Apr 07, 2009 · 88 posts
bagginsbill posted Fri, 10 April 2009 at 8:15 AM
Hehe - this is getting complicated.
No doubt, increasing the effective shading rate and/or the effective sampling rate makes an improvement. You can accomplish these either by making a bigger render then reducing, or by changing the values while keeping the same render size, or by doing both.
The choice of which technique to use should be made on the basis of all factors. The factors, as much as occurs to me at the moment, are:
1) Image quality
2) Render time
3) Memory use
As usual, these things are inter-related and not always linear. Meaning, if I double the effective shading rate, I will probably alter the render time, but it may be more or less than double. If I double the memory use, but it is still under my total physical RAM, it will go fast, but if I happen to go even slightly over my total RAM space, and I start swapping, then render time will go up 100x or more. I've seen renders that triggered swapping take days.
I do not know all the precise points at which RAM is exhausted, but I have heard it can happen just by making a larger render. In such cases, it may be better to change the parameters instead of changing render size. On the other hand, I've had at least one test where changing the parameter was much slower than changing the render size, even though the effective shading rate was the same.
Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)