Offline Rendering - General Questions and Hardware Purchase Advice Needed

vijayasimhabr

Folks,

Some context in place. Six months ago, I installed Daz 3D because I simply had too much time to kill with the pandemic and all that. Now, there is still too much time to kill, and I am still doing Daz. More importantly, Daz is easy enough to use that it is acting as a gateway towards the general 3D relate things.

Slowly, over the last few months, along with Daz, I am also looking at photorealism with 3D in general. For instance, I have managed to get some cool house renders with Sketch Up and V-Ray. I am now investigating Twin Motion from Unreal. I even got into Unreal for ArchViz. All this happened because of Daz.

For months, I had wondered why Daz 3D does not use my super expensive RTX 3060 desktop setup (I am in India, where all gaming gear is marked up by 60 to 80 % due to taxes, on top of the high prices of graphics cards these days) during rendering. So, now I have realized that

1. Real Time Rendering uses the graphics card.

2. Final Rendering or Offline Rendering uses the CPU.

So, my first question is, am I correct with my understanding of the real time and offline rendering above?

Now, coming to the second question. Since offline rendering is CPU heavy, I am thinking of buying a computer, which has a basic GPU but a very powerful CPU. Like an i7 or an i9. So, would that be good? I imagine a scenario where I do all the staging and "live" stuff, on my RTX machine.

Then, fire up the (future purchase) i7 or i9 computer for the 'offline' final rendering.

So, would this be a good way to manage my 3D pipeline?

Note : To keep things simple and tiny and quiet, I am thinking of an intel NUC mini PC with 32 GB or 64 GB RAM. I could keep the NUC on my existing desk, and simply connect it to my existing monitor as it wont be used except for while rendering.

barbult

No, final renders are done on the GPU, unless they are too large to fit. No matter what CPU you buy, it will be much slower than an RTX GPU. Do you have a 6 GB or 12 GB 3060? 6 is pretty small these days, but 12 should be pretty good. You also need quite a bit or RAM in your computer to support the GPU. People say 2 to 3 times as much as GPU memory. If your scenes don't fit in GPU, I suggested you try optimizations to reduce the GPU memory requirements. The forum is full of discussions about this. V3Digitimes Scene Optimizer is one useful tool.

Gordig

By realtime rendering, do you mean Iray preview? Both preview and rendering can use the GPU if the scene fits onto your GPU, which might be difficult if you have one of the 6GB 3060s. To get a scene to fit onto a GPU with limited VRAM, you'll need to engage in various optimizations, like hiding objects outside the camera, reducing texture resolutions, reducing the overall number of texture maps by any combination of removing bump and normal maps, reusing the same textures on multiple figures, pre-rendering figures and using them as billboards, etc.

vijayasimhabr

Perhaps, I should add some additional clarity.

@barbult

I have the 12 GB version. I am convinced that the GPU is not consumed during my final, offline rendering. However, the GPU is full utilized during my IRay Preview, Real time Rendering. Right now, I am happy with the performance of the RTX 3060 (which is all i can buy in India, anyway).

@Gordig

I am not talking about the preview, real time rendering. I am simply thinking of buying a second computer, just for the final renders. As the RTX desktop rarely uses the GPU itself during the final, offline render, I fancied getting a machine with a juiced up i7 or i9.

------------

So....

Further, from what I understand with all those videos I am watching from Unity, SketchUp and V-Ray (official tutorials, not some YouTube stuff), they seem to be imply that offline rendering happens on CPU.

Realtime preview rendering happens on GPU.

So, the information I am getting is, the final offline rendering, for instance, on V-Ray and Nvidia IRay, depends 100 % on CPU power with GPU not playing a role at all.

Are you guys saying that, offline rendering absolutey is GPU dependent? I am confused now :(

Gordig

V-Ray is a separate render engine from Iray, so it's possible they're using terminology that doesn't apply to Iray.

vijayasimhabr

Folks

My apologies. I just tested it again and I wish to correct myself.

On my RTX, both the GPU and CPU are in fact used 100 % during the final render. It suddenly hit me that the task manager does not show GPU usage. However, the Xbox Game Bar shows actual GPU usage, and I can see that both CPU and GPU are at 100 %.

Also, forgot to mention the RAM thing. So, the desktop has 32 GB of RAM. GPU has 12 GB RAM. So, that's my RAM situation.

So, combining what you guys said with my earlier knowledge, looks like, i already have the best setup I can buy here in India.

So, if I have to buy a second computer, looks like I simply have to buy a second computer which has the same specs as the current one.

Thanks for helping out folks.

As always, love the community in Daz 3D. Really, always, helping me when I need it the most. You folks just saved me a lot of headache and moneyache. Thanks.

barbult

GPU-Z is a good free tool you can download for monitoring the GPU usage, temperature, etc.

vijayasimhabr

Gordig said:

V-Ray is a separate render engine from Iray, so it's possible they're using terminology that doesn't apply to Iray.

I believe so. I will check their documentation again. I did remember reading somewhere that Nvidia (IRay) approach rendering slightly differently than the V-Ray folks. Thank you.

vijayasimhabr

barbult said:

GPU-Z is a good free tool you can download for monitoring the GPU usage, temperature, etc.

As of now, happy with Xbox Game Bar, but, I will add this to my work diary notes. Thank you.