For this how-to guide, I will use Blender 2.81. We will go over the basic features of how to use the layer system known as collections in the outliner. We will also look at how we can work with some related features to organize our work better.
Related article: 10 New or hidden features in Blenders outliner
When you start Blender, the outliner is the window in the top right corner. It is a list of all the objects is in your scene. Or to be more precise, in your file, since it can contain many scenes.
The outliner can show us any kind of data about our scene. Be it objects, lamps, and cameras or materials specific geometry or modifiers that we add to our objects. We can go so deep as to view each individual vertex position in our objects if we want.
We organize the outliner with the help of collections, and we can do all any operation to organize our file in the outliner. This is 90% of the outliners use case, but we can do other things as well, like browsing the available data on a property by property level or remove unused data. This however, is more advanced topics that we won't cover here. If you are interested in these things, I recommend reading the top 10 new or hidden features of the outliner.
We kind of said it already, it is in the top right corner, but what if you don't have it there for whatever reason, how do you bring it back?
Every window in Blender is an editor. Every editor can occupy any space of the interface except the top header row where you got your workspaces, menu and some other overarching stuff.
The outliner is an editor and can thus replace any other area that an editor occupies. Every editor has an "Editor type" menu. This menu is in most cases in the top left corner of any editor. Click it and choose the outliner on the far right side of the menu.
You can also hover your mouse over any editor and press "Shift+F9" to swap it for the outliner.
A third way is to press the editor menu, then while it is open, press "O" for outliner on your keyboard to switch the editor into the outliner.
In this article I have written more about how to change the interface around and how it is structured.
There is a lot we can do with the outliner in Blender but first and foremost it is a place where we organize our scene.
We organize our scene using collections. A collection is a container we put objects inside, so we can manipulate them as a group.
For instance, if you want to model a car, you might want to put each system of the car into its own collection. Then you can put all of those collections into a master collection that would be the collection to control the car as a whole.
We can also create instances of a collection to reuse the car or whatever other data we put in it.
For now, we will cover the basics. Right click in the outliner and choose "New" to create a collection.
Double click the collection or any object to rename it in the outliner. You can also press F2 to rename your selected object. If you want to rename multiple objects use "Ctrl+F2" to bring up the batch renamer.
We now have at least one collection that we created and renamed. You can now drag and drop objects into collections. Drag and drop will move the object or collection around. But an object can be a member of multiple collections as well.
While dropping the object you can hold CTRL to link the object into another collection. This way, an object can be part of more than one collection.
Note: We can drag and drop objects into one or more collections, but we can also parent an object to another. If you hold shift while you drop an object on top of another the dropped object will become a child of the object you dropped it on.
An object that is a child of another will inherit some properties of the parent object. Such as location, rotation and scale.
Another way to add an object to a collection is through the properties panel. Under the object tab, recognized by the orange icon, we can find the collection section. Here we can add many collections for our selected object to be a member of. We can also see all the collections the selected object is a member of.
Back in the outliner we will take a closer look at what we actually see.
Orange icons represent objects that we can manipulate in object mode in Blender. Some of these may have other icons on the same row on the right side of their names.
These icons represent different data that this object contains. This can be many kinds of data but a few common ones are mesh data, modifiers and materials. All of these kinds of data have different icons with different colors.
Mesh data has green upside down triangles. Green icons generally represent data that can only go into this kind of object. Mesh data can't go into a lamp object for instance. It needs a mesh object.
Vise versa, we can't have lamp data inside a mesh object or camera data inside a curve object. Data represented by a green icon is also often "core" data for the type of object it is in.
To understand what I mean with core data, lets move over to modifiers and particle systems. They have blue icons. Modifiers are represented as a wrench icon and particles is a dot with 3 other dots moving out from it.
Blue icons generally represent data that is not "core" data, but they depend on core data to operate. For instance a particle system need mesh to emit from and the mesh needs to be contained in the object represented by the orange icon.
Same goes for red icons that represent data that has to do with how things look. For instance materials, brush icons and texture icons.
Let's leave the data icons for now.
We also have an eye icon on the right side of most rows and just above that we have a filter dropdown list.
If you click the filter dropdown you can enable more icons. I suggest that you at least enable the camera icon. You can also enable the arrow icon for now.
If you are interested in what the rest of the icons do you can read the 10 new or hidden features in Blenders outliner article to find out more.
The eye icon will hide your object in the viewport. The object will still be rendered when you render out your final scene though.
To disable an object for rendering you can toggle the camera icon.
The arrow icon makes an object selectable or not in the 3D viewport. This can be handy if you work with multiple objects and tend to select the wrong one. In those cases it can be good to remember what the arrow icon does.
If you want to remove the outliner from its default position you can take the properties panel below it. Hover the top left corner of this editor, click it when the cursor change into a crosshair and drag up into the outliner.
A large arrow will cover the outliner and when you release the mouse button the properties panel will occupy it's space.
This heavily depends on the scene or object that you want to create.
We will look through a few scenarios.
An example of this is if we want to create a roof for a building, and we want to manually place each roof tile for maximum control. In this case we might end up duplicating a lot of objects that will be identical. If you don't intend to change these objects, first make sure that you duplicate with "Alt+D" instead of "Shift+D".
This will make sure that the same mesh data is used on all objects and it will save a huge amount of RAM. Next, make sure to name the first object so that whenever you duplicate, all the other objects will get the same name.
Also, place the object that you want to duplicate into a separate collection. All duplicates will then end up in the same collection, and they get much easier to manage as a whole.
If you need to select them all at once or hide them all at once etc. Then you can right click the collection and choose "Select objects".
This is the least strict scenario. If something is only going to be used once and is not going to be duplicated around. Then you probably don't need to worry so much about organizing your scene.
The general rule here though is that the larger the scene the more important it is to organize correctly into collections and name objects properly.
Collection has support for something called collection instancing. This means that we can take a collection and create an instance of it, or a linked copy.
If you recall we took the example of a car earlier. All cases that would be of similar nature, like a house or anything that is made up of multiple parts would fall into this category.
Make a hierarchy of collections if needed and put every subsystem into its own collection. Then put all these collections into a master collection that you then can create collection instances of.
You can add a collection instance from any collection. In your 3D viewport hit "Shift+A" and go to the "collection instance" menu to choose the collection you want to instance.
How to create a group in Blender? Groups in Blender has been deprecated and does not exist in Blender anymore. They have been replaced with the collection system. Same with the layers we had in Blender 2.79 and earlier.
How to enable render layers in Blender? Render layers are now called view layers and view layers can be created in the view layer menu in the top right corner of the interface. Just above the outliners default position.
How do you create an object in Blender? Hover your mouse in the 3D viewport and press "Shift+A" then choose any primitive object that you would like to add. You can also add an object through the add menu. By default, located at the top of the 3D viewport.