Number of vertices in a project

I somehow have the idea that for large projects, less verts is a kinda good thing.
so i made a railway engine of various parts…
put each part in its own layer and found the verts for each part- added them up.
then joined them togeather and it is a higher number of verts!
any idea why?
also i found that a cube- 8 verts of course, when you use subdivision surface ( it has a catchier name) i had hundreds of verts! so they will get removed!

does mirroring reduce the verts?
thanks all

There’s something called LOD (level of detail) in games, in order to reduce the graphics load when it can. You basically have different levels of detail (usually 3-5) that have less and less amount of verts, in turn, less amount of detail as well. The closer you get, the game uses a lower-detail model and replaces it in the scene. In 3D, it’s the same, except you don’t have to have multiple copies of decimated models, since most of the time you don’t put the camera close to the background. So the further objects get from the camera, the less detail you put into it, sometimes even replacing it with an image. There’s also something called “adaptive subdivision surface”, if you’re interested in newer versions of Blender, I suggest you look it up to see how it has advanced in the last few years.
The number of verts the entire project has does not change, whether you merge certain objects together or not. That’s a matter of how you work with the objects, not the poly-count.

The layer system did indeed have separate counts for vertices among layers (if I remember correctly), but if you want to show all of them I think you had to put them in the same layer. If you “add them”, well yes, the count gets combined. I suggest using the layer system, in line with managing separate parts so that you can work on single parts at a time if that’s what you want. Don’t forget to check if the parts still fit afterward, though.

The subdivision surface modifier is meant to smooth out pointy geometry with by adding some. You can reduce the count by selecting a lower level or step, which in turn, makes it a bit pointy, but no one has the best computer ever.

Unfortunately, the mirror mod does not reduce geometry. If you have the same object, I suggest using Instances:

BTW it is not a game.
mirroring does not reduce vert count. i see that now

What are Instances?

I suspect, too many verts will slow everything down.
now i have to figure out, for this computer how much is too much- verts wise.
i put the parts in diffferent layers, only to see how many verts were in that part.

I don’t think you should be too concerned about poly-count unless you still use something from like a decade ago.
Instances are copies of an object that don’t carry their own data. Basically, the original object moved to a different position as a “ghost” so that it doesn’t raise the poly-count. It uses the original’s data, so if you make local changes to the original like changing the shape or material, its instances get affected as well.

as this will be a model rail layout, lots of engines, cars and what have you, constantly moving… instances may not help.
yes i only use 2.69- as i know where things are in it. and will do everything i want it to do!