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Hello All,

Bit of an odd question but I wondered if anyone had put a lot of thought into the resolution vs SL/time curve in Maxwell?
I am sure everyone knows that when a noisy image is downscaled 4 times for example, the 4 pixels will blend together and produce an average colour therefore reducing noise.
I have just bought a Nikon D800 and was happy to find (after running some tests) that the 36mp resolution when downscaled to that of a 5d mk3 produces par, or superior high iso performance.
Basically its obviously the same with Maxwell, When I render very high res the details come out very quickly and it almost seems that an hour of 2048x1536 at low sl looks better than an hour of high sl 1024x768, more grainy yes, but more details and when downscaled its
barely below par.
has anyone played around with this concept? I had another idea that it might be better to render high res with low sl, run neat image and then downscale..
I would think that a renders time would increase to the exponentially squared sum but is the increase in time more than that?
Is a pixels colour determined on a subdivision basis? it seems almost that if that is the case one might as well render high and have the option of re-sampling in Photoshop...
my head is starting to hurt...

Yes, I played with that concept a loooong time ago.
For me it was sort of a work around for my very slow machine. So I rendered hi-res, denoised it, downscaled it.
The 'denoising' was a key factor, since denoising artifacts would disappear or become less visible after downscaling.
But in the end, when comparing untouched renders, it was not a big difference (at least back in those days), except that bigger render needed more RAM/CPU power.
So I pretty much let that concept go...

Anyways, you have to bare in mind, that some things (like reflections, refractions, caustics, SSS, etc.) accur at higher SL levels

m-Que wrote:Yes, I played with that concept a loooong time ago.
For me it was sort of a work around for my very slow machine. So I rendered hi-res, denoised it, downscaled it.
The 'denoising' was a key factor, since denoising artifacts would disappear or become less visible after downscaling.
But in the end, when comparing untouched renders, it was not a big difference (at least back in those days), except that bigger render needed more RAM/CPU power.
So I pretty much let that concept go...

Anyways, you have to bare in mind, that some things (like reflections, refractions, caustics, SSS, etc.) accur at higher SL levels

Yes you are absolutely right, I understand that high sl reveals more with greater accuracy and much like the perpetual motion machine it is impossible to 'trick' the laws of physics (or computer mathematics).
I was wondering if there was a sweet spot as it were, if there was a point at which the 'time curves' diverge to give you the best resolution/sl/time outcome.
Every time I set up a long render (over a weekend) I have to decide, sl20+ at medium res, or ~sl16 at High res..

i'd say try to not render a resolution higher than you/client need it.

in some cases the down sampling strategy works, probably best for large exterior images with plenty of light flooding the scene, but i have seen quite a few renders that looked flat and dull because the more complex interactions of light had not been processed far enough due to the high resolution they were calculated in.

i try to render everything to the native resolution of my screen which is 2560px in width except client demands it.

polynurb wrote: in some cases the down sampling strategy works, probably best for large exterior images with plenty of light flooding the scene, but i have seen quite a few renders that looked flat and dull because the more complex interactions of light had not been processed far enough due to the high resolution they were calculated in.

Totally agree. Generally the render has more subtle lighting detail at a higher SL. If you stop it at 8-10, you can lose that.

Interesting topic bograt, I had never thought of this strategy

One day I think I will run some tests and post the results.
to be continued....

I know for sure - I always render high res for as long as I can.
No low-res (like 1500X1000) looks as good as high res (like 4000X3000).

We render our finals at 5760x3240. High res rendered to a decent S.L. makes the lighting look amazing.

Bubbaloo wrote:We render our finals at 5760x3240. High res rendered to a decent S.L. makes the lighting look amazing.

Guess you got a little farm going then... I have to work off one mac pro dual Xeon (not my choice!) or my own personal quad intel thinkpad (which is strangely nearly as quick) so
I have to run the renders over a long weekend to achieve that kind of result but your right, It looks damn good when I do!
Computers are getting faster all the time so I look forward to not having to ever compromise