OTOY Forums

In lightwave native I use to be able to render out a section of the image as a limited region, the rendering would be much faster depending on the amount of the image that would be selected to be rendered. You could have this cropped or as a full frame with an alpha for compositing later.

I have tried everything I can think of (probably missing something) to get Octane to do the same thing.....but it seems not matter what I try the times don't get any faster with the limited region selected (not region in the IPR) Octane is calculating the entire scene but only rendering the region.

Is this a bug, am I not setting things up...or limitation somehow?

ok It gets even stranger....with limited region, only rendering probably 10% of the image I get 2M samples a second....with the full frame I get 8M samples a second....what???

I think it works like this :

Let´s say you have a 2000 x 1000 pixel render. You have set max samples to 1000.
Then you want to render just a region of it. Let´s say your region dimension is about 200 x 100 pixels. If you render it with the same samples amount (1000) then it will take the same time to render. But because your render region is 10 times smaller than the full render, you must reduce the samples to 100. Then it will take 10% of the time the full frame would.

Builtdown wrote:I think it works like this :

Let´s say you have a 2000 x 1000 pixel render. You have set max samples to 1000.
Then you want to render just a region of it. Let´s say your region dimension is about 200 x 100 pixels. If you render it with the same samples amount (1000) then it will take the same time to render. But because your render region is 10 times smaller than the full render, you must reduce the samples to 100. Then it will take 10% of the time the full frame would.

We'll if that's true it will be hard to get a "fix" layer to match perfectly. Also, I wonder why I would only be getting 2Ms a second instead of 8Ms on the full image?

I'm not sure I agree now that I think about it. If you have an IPR window open that is small you get higher samples a second...if you resize that window you get slower/lower samples a second and of course that will take longer to render up to a certain level....

Think there is something wonky here....

Builtdown wrote:I think it works like this :

Let´s say you have a 2000 x 1000 pixel render. You have set max samples to 1000.
Then you want to render just a region of it. Let´s say your region dimension is about 200 x 100 pixels. If you render it with the same samples amount (1000) then it will take the same time to render. But because your render region is 10 times smaller than the full render, you must reduce the samples to 100. Then it will take 10% of the time the full frame would.

This is true, there are problems with the render region statistics. All this issues with the region rendering sampling statistics will be fixed for Octane 3.

-Juanjo

juanjgon wrote:

Builtdown wrote:I think it works like this :

Let´s say you have a 2000 x 1000 pixel render. You have set max samples to 1000.
Then you want to render just a region of it. Let´s say your region dimension is about 200 x 100 pixels. If you render it with the same samples amount (1000) then it will take the same time to render. But because your render region is 10 times smaller than the full render, you must reduce the samples to 100. Then it will take 10% of the time the full frame would.

This is true, there are problems with the render region statistics. All this issues with the region rendering sampling statistics will be fixed for Octane 3.

-Juanjo

so to confirm Juanjgon I can't use limited region and it save me any time in the current plugin state (actually seems slower )? No settings I've missed or anything?

You can use the limited region without problems. It is not slower at all, the problem is that all the statistics about rendering when the render region is enabled are wrong.

If for example you render a 10% region with 1000 samples value in the kernel, the statistics are going to show that you have only 10% performance, and the render time to reach this 1000 samples value that you have in the kernel is going to be the same that the time needed to render the full image, but what do you get is a region rendered with 10.000 samples ... so in this case you could set 100 samples in the kernel to get the same quality than the full image at 1000 samples.

I think that there is a change about this issue in the latest Octane API releases. I am going to check it again to see if this changes can be added to the 2.2 plugin.

-Juanjo

I gave up using Limited Region months ago because the color never matches. I kept making the regions bigger and bigger so I could feather a mask in After Effects, realized I was wasting a lot of time, and decided that from now on if I have to re-render a patch, I'll just have to re-render the whole frame instead. There never seemed to be much of a speed advantage anyway, especially if you have a lot of pre-processing going on before each frame renders.