Which most impt CPU/GPU/RAM for orbiting around complex models

[rmehta]

This is not directly a rendering question... but what part of the system is the bottleneck when orbiting around a very complex model? I have a 125mb model that orbits painfully slow. I'm on wireframe with coarse rendermeshes. What would help my situation on either the hardware or software side?

[Micha_cg]

Re: Which most impt CPU/GPU/RAM for orbiting around complex models

Is Rhino slow or Vray?

Here you find a thread about large model rendering:

http://asgvis.com/index.php?option=c...18510#msg18510

I have the feeling, if I convert NURBS to meshes and delete the NURBS, than the model is faster handled at the Rhino viewport.

The render speed shouldn't be big affected by the polygon count. If you have the feeling, your setup is right, but the rendering is to slow, than check for duplicated objects (seldup and set sec ray bias at 0 -> duplicate objects should be black rendered), because this slow down the calculation.

[rmehta]

Re: Which most impt CPU/GPU/RAM for orbiting around complex models

Well actually it's rhino that i'm asking about... (The rendering is also slow since I have a lot of glass and transparency) but I'm asking about orbiting around the model in rhino.
When modeling nurbs in rhino what part of the system is responsible for the update time of the view and how responsive the system is when rotating complex models?

[dalomar_cg]

Re: Which most impt CPU/GPU/RAM for orbiting around complex models

Its a combination of all three actually (with RAM possibly being the least). Basically when your orbiting around the model two basic processes have to go on...the first is that where the 3d model lies in 2d space has to be calculated, and secondly, the viewport itself has to be rendered. The first operation is very CPU intensive. Actually if you open up windows task manager, rotate any model around (a medium size one will do), and watch the processor activity, you'll likely see it be jumping around with the rotation of the view. The second operation (the rendering/drawing of the viewport) is a gpu thing, so all the info that is precalculated gets passed off to the GPU and puts it up on the screen. With too little ram both the calculations of the model (the first part) and the transfer of that info to the GPU will slow down, so enough RAM is important

The thing about viewport stuff is that once you have a big model, there really isn't too much you can do about it other than hide as much stuff as you don't need and work in wireframe mode.

[rmehta]

Re: Which most impt CPU/GPU/RAM for orbiting around complex models

Thanks, good explanation.

Out of curiosity at what MB file size, with all objects shown, do you notice significant slowdown from "realtime"?

[dalomar_cg]

Re: Which most impt CPU/GPU/RAM for orbiting around complex models

Depends actually on a number of things...since its a back and forth between gpu and cpu there's a lot at play. I personally always work with 1 maximized, or major viewport, so that means more pixels to render for the gpu as well. On my workstation, I switched over to 2 24" monitors about 3 months ago, which means that I've got a rhino viewport that is about 1800x900. Even with a stout graphics card and cpu, I'll notice a slowdown with complex model a little sooner than I would with my laptop, simply because of the size of the viewport.

Depending on whether the model is straight forward (a lot of flat surfaces) or very curvy, things may slow down as well...Meshes will take up much more processor power/memory once they get more complex, so sometimes certain types of objects will be enough to slow things to a hault.

One of the key things I try to do is have a good layer structure, so I can hide things easily. I also use a lot of hide and hideswap as an easy way to pick and choose the things I work on. The last thing I do is actually from 3dsMax, where they have something called Isolate Selection, which allows you to isolate just what you have selected, but you can then unisolate back to the previous object you have shown...this is something that I've found extremely useful, so I found a way to mimic that behavior in Rhino. The following are two macros that I use to do this...one for the isolation, and another for the unisolation. Copy and paste those into a button (Lmb and Rmb) and you're good to go.

isolate selection

_NoEcho
_SetRedrawOff
_Invert
_Group
_SetGroupName "Isolated"
_Hide
_SetRedrawOn
_Echo

unIsolate selection

_NoEcho
_SetRedrawOff
_SelNone
_ShowSelected
_SelGroup "Isolated" Enter
_Ungroup SelGroup "Isolated" Enter
_SetRedrawOn
_Echo

Note: clicking on the unIsolate button without something Isolated will just turn Redraw off...press ESC 2 or 3 times and it will come back