Need Some Basic Help With Scene Building

Hello, I’ve only been using Blender for a couple months now and new to 3D in general so I am still trying to understand a lot of things, especially on the general workflow of things. I’m having a real problem with my scenes once I get them further along, to a point where trying to make changes is a nightmare.

For example, my entry for last weeks competition had about 1m polys, 2 cloth physics, smoke physics, about 5 particle systems, a manuel bastioni IK rig, 5 or so lights, couple dozen objects and tons of textures/matierals… So at that point trying to do anything in the scene is impossible, even moving small objects. I have to move them to an empty layer first to do anything at all.

So how do you handle this? Is this where render layers and compositing comes into play? Should I be separating these things into individual renders and then combining them in the compositor? Should I not have everything put together in my scene and just render it?

I feel like I am doing something wrong here, because even my lesser of scenes get horribly slow after towards the end and I just think I must be doing something wrong. Please, any insight is appreciated.

split things up and keep it dynamic. let me break it down.

you said you ended up with 1m polygons, this is likely with stuff that has subsurface modifier on them. here its very simple, turn down the View number, while keeping the render value to what you want it to be in the end.
if you still end up with 1m polygons, try to find out what takes up the most of that budget, and move it to a separate layer, or move stuff that does not need to be visable all the time to be on a separate layer.

cloth physics is not a problem, however there is something i advice you to do. up on the top row, create a new scene for the physics, and in there, only add the objects you want the cloth to interact with, and also try to keep the polycount of these objects relatively low, even lower than you want in the final result. it wont change the cloth sim very much, and will drastically increase sim speed.
this will keep the simulations off of your main scene.
and when you are done, simply bake the simulation, which will give you 1 keyframe on every frame, and copy that object over to your main scene.

^ same rule applies to smoke physics, make a separate scene for it, then port it back when ur done with it.

Particle systems are not as important, they just tend to be resource heavy no matter what you do with it. so all i advice you to do here is simply put them on different layers, and keep them separate from eachother, then bring it all back once you want to render it all.
keep in mind, most people exaggerate the polycount on particles, if i say you can likely get away with using 1/10 the polycount on your particles, im likely correct.

keep the rig on a separate layer aswell. it wont affect performance very much, but it makes somewhat of a difference.

lights wont affect viewport performance, but try to use HDRIs as your main source of light. it just looks better.

I have the opposite problem, where I won’t let myself do anything that might become too complicated, so don’t over-correct. With that in mind, and in addition to finalbarrage’s advice, here are a few tips:

Spend some time at the beginning of the project to plan things out, do some low-poly models, some grease pencil sketches, some color studies. This can help you see what you need and what you don’t need, where to put a lot of detail, and what to maybe throw a texture on and forget about it.

Learn how to bake diffuse and normal maps onto low-poly meshes. You can’t use it for everything, but where you can it will drastically reduce your render times and poly-counts. Same kind of idea for replacing full grass geometry with textures on billboard particles. Or replacing a smoke sim with a selectively blurred transparent mesh object.

Yes, use the compositor where appropriate. If you can render several different scenes and composite them all together, go for it! You could even keep stuff in completely separate files if you want to really segregate the complexity.

@finalbarrage thank you so so soo much for taking the time to break it down like that. It actually helps a lot. Using different scenes is also a great idea, not sure why I forgot about that.

@dudecon thanks to you as well, and I know what you mean about about correcting lol. Also your note about baking is spot on. I haven’t done that yet, so after I scult a bunch of detail onto a mesh I have been leaving it, but I need to convert that to a texture through a bake… I don’t typically like baking things because it can get that fake 2d texture look, but for simple small details that eat up polys is a great idea… It’s just such a pain, especially if I need to make a change.

Thank you guys so much for the tips!