Effect of poly count on render? Objects vs. polys?

[JIII]

hmm I am not certain about this but polygonal objects have to be calculated by the computer but primatives are already in the program there which makes the rendering simpler. just a wild guess though. yes instancing lowers the time significantly.

I have found that its not polys which take forever to render its textures.

you can have 500k polys and render times of not long but add in textures and boom those rays are crawling from one place to the next.

[brammelo]

about the instances: the only thing that goes faster is editing. But when it comes down to rendering, the render engine replaces the instances with the source object. So there's no noticeable difference there :-)

cheers,
BaRa

[Iggy]

Oh bummer. I have some moderately high poly objects that I instanced, thinking that it would save render time. (Though now that you mention it, it has definitely made a difference in the editing.) I don't have the time to remodel them to save polys, though I might be able to modify them some, if it seems like it will help. I guess I won't know until I apply the textures. I have a feeling that this thing is going to have a long render. Once I get the model work complete I'll get a WIP going.

Any more insights on this? Objects vs. polys?

[cookepuss]

It might sound obvious, but you also have to consider the rendering method. Poly count can have a huge effect on that.

For example, I'm currently work with a scene that borders on 2-million polys. Yeah, that's a very heavy scene. As a general case, render times are pretty slow. They get even worse if your turn on the cel renderer. Hidden line removal drives that rendering time up. This is a direct effect of the poly count.

I rendered a 30-sec cel rendered walkthrough of this scene on a single CPU P4-3GHz machine. Render time..... 13 hours.

Switch to radiosity, a sky light, & a single spotlight. Render time for this 2mil poly scene (on a single CPU P4-3GHz) jumps up to..... 6.25 DAYS

Textures are off.

Kinda makes sense to network render it out, eh? :)

[Iggy]

Yah I'm starting to worry a little bit. I had hoped to keep the times down. I will probably save some on the textures. I'm not going for a super realistic look. As much as possible is good, but my animation is a sales tool for a machine and no one will be concerned if it does not match reality exactly. In fact I am quite certain that I am the person most interested in making it look realistic, if only for the practice. I'm sure I won't use radiosity or caustics here. I will have to do some quick materials in the near future and see how it affects the render times. I'm planning for a 2 minute animation, though I am not sure right now what the frame rate will be (probably 15). That's 30 hours at 60 seconds a frame, which is probably optimistic.

Learning curve!

[Iggy]

So I'm compelled to wonder yet more on this topic. What textures render faster: bitmapped or procedural, or does it just depend there too? I'm just starting to play with textures on my model and wondering. And is it so, that instances only help in the editor? Well, I guess that it could also be very helpful if you have a complicated texture that gets repeated... Or you're editing a field of 1000's of objects. Okay, so I suppose I'm answering my own question... But really, a field of a 1000 objects all the same will render in the same amount of time whether the objects are instanced or not? Sounds like an experiment is in order.

I'm obsessed!

[Pate]

Hi!

Bitmapped textures usually render much faster thanprocedural textures (depends a bit on the complexity of the procedurals, of course). Try a multi-level Bhodinut Fusion tree with 3D noise on many channels and see render times skyrocket.. :)

With bitmap textures, you could try the various interpolation methods (MIP/SAT/etc). If you can use NONE that is the fastest, but usually it is not usable.

Experiment away, and let us know the results!

Pate

[brammelo]

Polygons vs Objects: it's actually the same story as instances. It's easier to edit Objects, because you have interesting attributes. But rendering is the same, because you have the same amount of polygons. After all, an object is just some piece of logic with a polygonal output.

I haven't seen it confirmed yet, but it might even be that Objects take a tadd longer to calculate, because there's a conversion step which isn't there with pure polygons - but I'm not sure about this one.

What does change is the size of you file: polygons consume a lot more diskspace, which could mean that when working with polygons, you have less memory available - but again, I am not sure about that.

Those are actually questions Srek should answer - he's doing support for Maxon :)

Cheers,
BaRa

[Iggy]

Thanks for the input Pate and Brammelo. I did some experiments last night with a model that I downloaded from noctua (his feurzeug: a lighter). I duped it 10 times (not instanced) and rendered: 2:28. I duped it 10 times as instances and rendered and again: 2:28. So there is definitely no advantage to instancing from the context of rendering. (I also couldn't see any particular advantage in the editor.) Given that, I'm sure that brammelo is correct also, that objects don't speed anything up in the render either.

So continuing from here, what is the point of instancing? I'm certainly missing something here. Srek? Kaiskai? Anyone?

MUST...LEARN...

[brammelo]

It speeds up editing, not the refresh of the editor window. When you use instances and you want to change the shape of the object, you only change it once (the source object) and the instances follow.

If you didn't use instances, you'd have to change the copies one by one or you'd have to duplicate the changed source object again. So it's really about editing speed, not about redraw speed.

Cheers,
BaRa

[Iggy]

Oh, of course! [Fleshy slap of hand on forehead] I misunderstood what you said before, brammelo. I've obviously been wasting some time with a lot of instancing when I should have been modeling. Glad I got that figured out now. Thanks to everyone for their help.

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