[seghier]

i rendered a scene and used multilight
with some lights i get clear result at sl 18
with other lights i need to use sl 20 or +
is it possible to use extra sampling with lights ?

[eric nixon]

+1

[Fernando Tella]

Without knowing the in and outs of extrasampling, it works by selecting well defined regions on screen. It speeds up the process by rendering only part of the image instead of the whole, but lights usually flood the whole image and don't have a defined edge. I guess you want a completely different thing: instead of selecting a region you would like to stop the calculations on some lights and continue with the rest, right?
Maybe that would somehow distort the light solution?

I can see some situations where that feature would be useful, like lamps that don't contribute much to the illumination of the image apart from the look of the lamp itself.

Maybe that would not be necessary if the "importance" of lights were automatically equalized before starting the render so all the lights cleaned at the same time (which is something that can be done by hand but is a bit tedious).

[numerobis]

+1

[seghier]

stop the calculations on some lights and continue with the rest, right?

yes is the same with actual method ; stop calculations with some materials or objects and continue with the rest

[Fernando Tella]

I would say current method is more like "continue render in a region" based on a mask. You can obtain masks from objects, materials, custom alphas,... but not from lights. I think it's a different concept.

I mean, I find it useful, don't get me wrong, but I guess it's not just adapting the thing to lights. Hopefully it's easy to do.

[seghier]

i don't mean masks
the light applied to all the scenes ; i don't mean apply light to some objects ( we can use block emitter in this case )
if we use two lights ; one light quickly calculated and give clean image but the second need more time
if we have option to stop calculation of any light in the scene
sl 18 for the first and sl 23 for the second : it's extra sampling

[Fernando Tella]

I understand your point and find it useful, but what I mean is that the concept is different from current extra sampling as you would be rendering the whole frame nevertheless, just turning off the calculations of some lights.

[eric nixon]

(which is something that can be done by hand but is a bit tedious).

Fernando, that's a good point. That's something I've forgotten. Also a vague recollection something changed in this regard, but pretty sure thats the way it works now.... The idea is to make the small lights extra bright then dim them with multilight, right?, but then how much brighter? Trial and error would indeed be tedious and kind of counterproductive with a deadline looming.

Maybe that would somehow distort the light solution?

... No worries there, it wouldn't change the appearance of anything.

[Fernando Tella]

I usually do it by eye-balling, yep. I don't know other way to do it with image based emitters, for example.

[rdtBCN]

Hi,
I jump in the chat, as I would also find useful a feature where you could select which light sources would need extra sampling and stop the others when they are clean when using multilight. We actually have an interior scene where all passes of the lights inside the room are clean at 18 SL, but sun and environment require extra sampling.
Hoping this could be implemented in future versions!

Roberto

[dariolanza]

Hello rdtBCN,

Extra Sampling per light is not as time saving as it first may sound.

First, it would involve a different way to store data on the MXI, that would make our well-packed MXI file to be at least double weight.

Second, as fortunately in Maxwell the number of light sources doesn't impact the render times as dramatically as in other render engines, sampling 2 lights on the same scene will not be much faster than sampling 5. If your render is still noisy because of a couple of times, I would suggest you to add a couple of Sampling Levels more to the whole scene. Being other lights on this new render wouldn't make it significantly slower, and the gain in visual coherency, algorithm cleanness and file size and Ram needs do will be noticeable.

If you don't have more time to render, other solution is that if there is certain light noisier than others, you can use the unique capabilities of Multilight to separate your light buffers in Photoshop or After Effects, and apply any noise reduction strategy only on certain selective lights, while maintaining the sharp details from the rest.

In addition to that, if the noise from that "noisiy" emitter is affecting certain located area or object, you could easily use the Extra Sampling to clean it up.

And finally and more important, if in your interior what is causing that noise is definitely the indirect lighting from the environment and sun, I would strongly suggest you to follow these photographer advises to speed up this kind of situations: http://support.nextlimit.com/display/tu ... or+renders

Let me know if this helped to clarify this question.

Greetings

Dario Lanza

[rdtBCN]

Hi Dario,
thanks for the reply and insight on the issue. It was just an idea after seeing that the MXI extracts an image for each light source when importing it in After Effects or Photoshop. Then of course, we users just ask and request without the knowledge of the software build

In the end we rendered a couple of samples more and the image looks really good, hardly grain, just enough to make it look well balanced/realistic.

Greetz!