Progressive Image Sampler Question

[Dentzz]

Not sure if this is a limitation of modo or Vray but is it possible to get more info when rendering with the Progressive Image Sampler. I can tell that the image is cleaning up but it will stay at the same percentage for a long time and jump 10 or 20 percentage points, it would be nice to have some kind of more info or at least a clock to know how long it has been rendering for.

Also progressive image sampler seems to be slower compared to using adaptive when using the noise threshold as the stopping point. Visually Progressive seems to finish at around the same time but just hangs at 100% for awhile. I know that the samplers work differently and for a single frame I can just stop it but is something going on that makes the progressive sampler hang at the end or is it that the progressive sampler just happened to be slower on the scene I was rendering and visually looked similar at a lower quality noise threshold?

[jonmoore]

I'd personally only ever use Vray's Progressive Image Sampler as a high quality preview (it doesn't cut any corners in the same manner that RT does) but I find it to be generally slower than using the bucket renderer. It's annoying that neither renderer provide timing information on the render until the render is complete or stopped (unless I'm missing something) but that's for another thread!

I think some Modo folk might be tempted to use the Progressive Image Sampler in the same manner as using Modo's Preview renderer in high quality progressive refinement mode but Vray doesn't provide the same experience (or efficiency for that matter) with it's progressive mode. It's a great option for quickly getting a macro view of scene composition and lighting/surface interaction, but you have far more control by individually setting subdiv's for lights/surfaces and using the bucket renderer in adaptive sampler mode.

[Dentzz]

Oh! I was under the impression that the progressive sampler was the future way of doing things. In the documentation they mention the universal V-Ray settings, where you let the computer do most of the calculation on which items need more sampling. The progressive render is set to these settings by default which I assumed is the way to do things correctly going forward. The main reason I assumed you wouldn't want to use the progressive sampler was just for ram usage reasons and that it seemed for Distributed rendering they mention that if something goes down it hangs. Is this not true?

[vladimir.nedev]

I am not an expert on the progressive sampler, but my guess is that when you set a "noise threshold" above 0.0, the percentage shows the pixels that have reached the noise threshold.
You can add the "Shaded AA Samples" output in MODO. With the progressive sampler, it seems, white areas in this render element, denote pixels that are still being worked on.
So if large areas finish at the same time, you see this jump from 10 to 20 percent for example.

I can add a timer, displayed after the name of the current task (for example "V-Ray Render : Rendering image... 0h0m10s elapsed / 0h0m20s left").
The estimation might be very wrong though, as there is no way to know how much time the task will actually take.

And this will be possible only in MODO 901, and after I switch to Qt for our UI (which I am doing at the moment).
The MODO native monitor/progress bar doesn't allow changing the displayed text after it has been created, it seems.

Greetings,
Vladimir Nedev

[jonmoore]

The universal Vray settings have been floating round the community for a long, long time, and are not something that I'd consider the future way of doing things.

The truth of the matter is that if you have the DR CPU grunt then brute forcing your way to an end result will always provide the most accurate result. But there are far, far quicker ways of achieving something that looks very similar in a fraction of the time if you learn optimise your scenes.

Just my tuppence haypenny.

[jonmoore]

And this will be possible only in MODO 901, and after I switch to Qt for our UI (which I am doing at the moment).
The MODO native monitor/progress bar doesn't allow changing the displayed text after it has been created, it seems.

Greetings,
Vladimir Nedev

Great news. Had no idea that you were intending to switch to QT pre v1 launch.

As a side note the main problems I'm having with Vray for Modo seem to be caused by limitations in the API/SDK. One of the delights of working with Modo's native rendering engine is the workflow. It seems to me that at the moment you're unable to mirror that workflow due to the API/SDK (and this is putting Vray on an unequal footing as a result). Really hope The Foundry team are able to change this in the future as it's not just the quality of the results that makes you love a rendering technology but the ease of getting those results too.

[vladimir.nedev]

Well The Foundry is certainly working in that direction.
They switched to Qt for MODO 901, which will make it possible for us to dock our VFB in the MODO UI, and will also fix a number of smaller glitches on the Mac version (like not being able to right click in the History panel to enter a Note).
They also added the Render Cache API, which gives us access to their fur/hair. The API needs some more bug fixing, but it is getting there.
About for the procedural textures that you asked about, it really depends on how they wrote them initially. It might be a huge task for them to give access to 3rd party renderers, especially considering how many procedural textures they already have.

Greetings,
Vladimir Nedev

[Dentzz]

The elapsed time would be pretty good. Time left would also probably be nice though is it comparable to other render engines estimation or is something about progressive make it really far off?

Also as an aside does handling item masks to work with particles something that is able to happen or being worked on in the future?

[vladimir.nedev]

The elapsed time would be pretty good. Time left would also probably be nice though is it comparable to other render engines estimation or is something about progressive make it really far off?

The estimated time left will be based on the time elapsed so far and the percentage of the work done.
So, for example, if the progress bar shows 50% and this took 1minute, then the estimated time left will show 1minute as well.
The estimation will probably be off, if you use a noise threshold. In this case, it is impossible to know how much time it will take each pixel to clear to the specified noise threshold.
If you disable the noise threshold (put it at 0.0), I think the progressive sampler progress bar will act very predictably, and the estimated time left will probably be very close to correct.

Also as an aside does handling item masks to work with particles something that is able to happen or being worked on in the future?

Can you start a separate thread and show me an example about this ? I am no sure what you mean, we don't support particles in MODO yet, only the Replicator.

Greetings,
Vladimir Nedev

[Dentzz]

The estimated time left will be based on the time elapsed so far and the percentage of the work done.
So, for example, if the progress bar shows 50% and this took 1minute, then the estimated time left will show 1minute as well.
The estimation will probably be off, if you use a noise threshold. In this case, it is impossible to know how much time it will take each pixel to clear to the specified noise threshold.
If you disable the noise threshold (put it at 0.0), I think the progressive sampler progress bar will act very predictably, and the estimated time left will probably be very close to correct.

Not sure I am in a position to know if other people would or would not want a time remaining. Personally I would rather have that info as it is something that is usually in the modo render window but it jumps around a lot based on what it has rendered with no accounting for what is left. Also if RTGPU can eventually be used for final frame rendering would be nice to have time left when setting max paths per pixel.

Can you start a separate thread and show me an example about this ? I am no sure what you mean, we don't support particles in MODO yet, only the Replicator.

Greetings,
Vladimir Nedev

Will do.

[vladimir.nedev]

For tomorrow's nightly build (the one from 2015-07-26),
our progress bar in MODO 901 will include how much time has elapsed since the beginning of the current task.
It will also include an estimation of the remaining time.

Greetings,
Vladimir Nedev

[Dentzz]

Great will have to try it on 901 if I upgrade in a week or two.