Hi there,
can someone explain to me the difference between instancing a collection and using alt+d?
Thanks.
Hi.
As I understand it…
Alt-D makes a seperate copy of an object. That seperate copy takes up RAM resources.
“instancing a collection” does not create a seperate copy. Instead it tells the renderer “show this again… oh, and put this one over here - away from the first one.”
Just my take…
Good luck Blendering!
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@calpgrmr isn’t making a separate copy shift+D? Or is Alt+D also a separate copy but trasnfers the changes and attributes of the original one to the copies?
Another question: once I create an instance collection, if I duplicate that collection (with shift+D) will that create a separate object, or another instance of the original object?
Thanks!
Alt-D will make a linked duplicate of one or more objects that you have selected. The duplicates will have there own origin and in the case of multiple objects multiple origins. The duplicates can be rotated scaled etc individually. The same thing applies if you right-click “duplicate linked” a collection.
When you instance a collection (by right-click “instance to scene”) a new “empty-object” appears. You will see all the objects in the collection duplicated but they will all be “bound” to the empty (they are also linked to their original objects in the same way as Alt-D).
You can also instance collections to the current scene by creating an empty and under the properties tab - instancing - select collection.
The big difference is that the objects in the “instanced collection” are treated as one object, and they only have one origin (the empty). So when you move/scale/and rotate the instance you are really transforming the empty.
To move/scale/rotate the individual objects in the collection instance you have to do it with the original objects.
If you duplicate the empty you will be duplicating the entire instanced collection ie. making another instance of that collection.
Memory wise there is no difference in terms of geometry-vert-count, both methods make linked duplicates.
There will be a little difference for many objects in that with Alt-D (or “duplicate linked”) each duplicated object has its own personal origin and transformation values. An instanced collection only has one origin and one set of transformation values.
“separate object” and “instance” are 2 different things (collection instance is in the Add menu)
For example… in Ram…, if an object is 1000 bytes,
100 copies would be 100,000 bytes.
100 instances of an object is (in theory) still 1000 bytes, but drawn 100 times.
But I could be wrong.
Yes I forgot that one, another way to instance a collection. This will also add an empty.
Edit:
It is a bit confusing that Blender will name the empty with the same name as your original collection and the empty is often hidden inside one of the instanced objects.
But if you select the instanced collection and look at its object properties you will see that it is in fact an empty that is instancing a collection (look at the “properties tab - object properties- instance” and “object data properties”)
Thank you both.
So is alt-D an instance too?
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Technically I think not, maybe it is the other way around, instances are “linked copies” that are instanced or “summoned” on something (like on verts, faces, edges, points, empties etc).
Alt- D makes “free standing” linked copies that do not depend on another object for their position.
…I could be corrected!
I edited this line to get rid of the word (instances)
Thanks for the info! It helps a lot.