Is RT not really recommended for IPR rendering ?

[JezUK]

I'm new to the IPR party (I know), so I've been having a play with it today.

But I'm getting some inconsistencies with how IPR works in different versions of 3DS max, and swapping between V-Ray Adv. and V-Ray RT (right now my brain is a mush but I've been playing with 2016 / 2017, gave up on 2014).

Would I be right in saying best to only really use V-Ray Adv. with IPR ?

Also, why is IPR Adv rendering more noisy even when noise settings etc are set to the same as non-ipr, production methods ? (and I've left it to render long enough). Obviously there's no such thing as a free lunch !

[Alex_M]

Maybe I'm wrong but I think you're mixing up IPR with RT which are two different things. IPR stands for Interactive Production Rendering using just your CPU. While IPR is another method of rendering your scene with Vray Adv, RT is pretty much a separate render engine in itself and is used only interactive (or production) rendering only with your graphics card/s. I guess you're talking about RT? I would not recommend to use CPU with Vray RT as it's pretty much always slower than using your graphics card. It's only useful when there are some maps or features that are not supported by RT GPU but this list gets shorter and shorter with each version of Vray.

I guess I should put it this way. They pretty much serve the same purpose - working on your scene and seeing it update in real time for fast iteration. If you want to use your CPU for this purpose, I would use IPR. If you want to use your GPU for interactive rendering, use Vray RT. Just know that both have pros and cons so you should decide which to use depending on the particular job.

[JezUK]

Hi Alex,

Thanks for your message, but I am talking about IPR - you can choose the Renderer to be V-Ray Adv or RT, whilst keeping the Target as "Production".

Oops..... where I was saying CPU or GPU, I was meaning using the CPU based Adv Renderer or RT (I did say my brain was mush ).

When you do that (choose RT as the Renderer for Production), you get an RT with a lot more features (in RT) than when using RT in Activeshade.

(I'm aware of using CPU or GPU as the Engine type for RT and wasn't referring to that )

Sorry for being unclear - so I'll say again, I'm comparing V-Ray Adv vs V-Ray RT in Production rendering, using IPR.

Many thanks.

[JezUK]

I've since corrected my bad English in my original post - but so that it's clear, this is where I'm talking about

[Alan Iglesias]

Would I be right in saying best to only really use V-Ray Adv. with IPR ?

IPR is, by definition, currently rendered only with the V-Ray Advanced Renderer.

Vray RT with Active Shade is a form of interactive rendering -- and the only one we really had up until recently.

However, many folks wanted something interactive that would match the V-Ray Advanced Renderer in every way with perfect precision, and thus IPR was born. So that is why IPR is V-Ray Advanced Renderer-based.

-Alan

[JezUK]

IPR is, by definition, currently rendered only with the V-Ray Advanced Renderer.

Vray RT with Active Shade is a form of interactive rendering -- and the only one we really had up until recently.

However, many folks wanted something interactive that would match the V-Ray Advanced Renderer in every way with perfect precision, and thus IPR was born. So that is why IPR is V-Ray Advanced Renderer-based.

-Alan

Whilst I agree with you, here at Chaosgroup's TV channel on YouTube, there is this....

https://www.youtube.com/watch?v=zw9k19uZB5E

Before then, I was experiencing discrepancies with the features when using IPR, the main one being that for GPU rendering, the render would carry on, regardless of the time limit I would impose, whilst for CPU, the time limit for renders would be respected. Maybe that's a bug ?

Anyway, hence the question - I was hoping for an official answer from Vlado or another Chaosgroup member.

[Alex_M]

But I'm getting some inconsistencies with how IPR works in different versions of 3DS max, and swapping between V-Ray Adv. and V-Ray RT

While the principle of work of both is the same, IPR in Vray Adv uses Vray Adv's engine to interactively render your scene and allow working on it at the same time, while IPR in Vray RT uses RT's engine to interactively render your scene and allow working on it at the same time. That's why there's differences in your renders. As I mentioned in my previous post, Adv and RT are basically 2 different render engines, you'll never get absolutely identical render results from both in more complex scenes. Or at least at the moment, in the future that might change when GPU rendering gets more and more mature.

Would I be right in saying best to only really use V-Ray Adv. with IPR ?

No. Use whatever best suits your situation.
Use IPR in Adv if you plan to finish your project with Adv (CPU rendering). If you plan to finish your project with RT (GPU rendering) then use IPR in RT.

Also, why is IPR Adv rendering more noisy even when noise settings etc are set to the same as non-ipr, production methods ? (and I've left it to render long enough). Obviously there's no such thing as a free lunch !

Because IPR by nature is built and optimized to interactively render changes in your scene on the fly as you work on it, not produce final quality images. Otherwise interactivity would be greatly diminished and would defeat the purpose of IPR.

So to summarize if it didn't get clear already, never use IPR to render final quality images because that's not the purpose of IPR. For final images use either Vray Adv with the "Render" or "Render last" button or Vray RT in Production mode with the "Render" or "Render last" button.

[JezUK]

While the principle of work of both is the same, IPR in Vray Adv uses Vray Adv's engine to interactively render your scene and allow working on it at the same time, while IPR in Vray RT uses RT's engine to interactively render your scene and allow working on it at the same time. That's why there's differences in your renders. As I mentioned in my previous post, Adv and RT are basically 2 different render engines, you'll never get absolutely identical render results from both in more complex scenes. Or at least at the moment, in the future that might change when GPU rendering gets more and more mature.



No. Use whatever best suits your situation.
Use IPR in Adv if you plan to finish your project with Adv (CPU rendering). If you plan to finish your project with RT (GPU rendering) then use IPR in RT.



Because IPR by nature is built and optimized to interactively render changes in your scene on the fly as you work on it, not produce final quality images. Otherwise interactivity would be greatly diminished and would defeat the purpose of IPR.

So to summarize if it didn't get clear already, never use IPR to render final quality images because that's not the purpose of IPR. For final images use either Vray Adv with the "Render" or "Render last" button or Vray RT in Production mode with the "Render" or "Render last" button.

Thanks Alex, I really appreciate your thorough answer

I've been rendering using RT with either Render or Render Last - and am loving the productivity / speed increases I'm experiencing as a result.