Align selection to cursor does not align with geometry origin

Support Basics & Interface
1

I have a model of a car with each car part being a separate model. I’d like to align all parts such that the geometric center (geometry origin) of the whole group aligns with world origin.

What I’ve tried:

  1. Select all parts of the car
  2. To be safe I set the origin of all parts to geometry center (set origin → origin to geometry)
  3. Then Shift+S → Selection to Cursor (keep offset):
  4. And here is the problem - the geometric center of the selection of all parts does not align with the 3D cursor in the world origin!
    image
    image2325×1107 502 KB

To show it differently I joined all 3d models of all parts into a single mesh. Aligned the origin to geometry center (set origin → origin to geometry) and set the position of the model to world origin. As you can see, the merged mesh has the origin exactly at world origin, but not the group with individual parts:
https://blenderartists.org/uploads/default/original/4X/f/a/4/fa4444934a8bfa79c6d77bc9567e13da93fd323b.jpeg

ps. I am slowly going insane trying to figure this out :stuck_out_tongue:

2

:slightly_smiling_face:
https://youtu.be/9bxOKHx2VuU
https://youtu.be/_qLDiJ6AimA
https://youtu.be/n1lCK8WH62k

3

It’s because you’re keeping offset, if you want everything to have the same origin, don’t use offset

4

If I dont use the offset then every part goes to the world origin (where the 3d cursor sits). Or did you mean something else?

image
image1434×692 250 KB

6

Thanks, but unfortunately I saw those videos, and they don’t provide a solution to the problem.

Here is a better explanation of the problem - the combined mesh has a geometric center in a different spot than a group of the same objects - https://streamable.com/jepxc6

How do I make a group of objects to have the same center as if the mesh was combined?
Also it is really weird the center of a group of objects is not a geometric center. Why? And what does Blender use, if not a geometric center?

7

Even better explanation of the issue:

image
image2311×1318 499 KB

8

I think that the point where gizmo appears is at the center of all Origins and not geometry…

9

I found the solution! If one selects several objects and does Shift+S → selection to cursor (keep offset) - Blender uses a mid-point of all object origins.

The solution for my problem, to have a geometric center (center of the bounding box of all objects) is to do the same as above, but doing it NOT in the object mode, but in the EDIT mode! It works!
So, select all objects → go to edit mode → select all objects → Shift+S → cursor to active. It will place the cursor at the geometric center! The center of a bonding box encapsulating all objects. Then one can create an empty parent and have your geometric center :slight_smile:
I only spent a whole day solving this issue :slight_smile:

10

Yes, this is exactly the problem. I wanted the center of geometry, the center of a bounding box.
I found the solution, see above

11

In object mode the median point (as in the pivot mode) is the median point of all selected objects, or rather of all selected transforms, not accounting for their data (=meshes). On the other hand, if you “set origin to geometry” of an object, depending on the operator properties (median center or bounds center) it’ll either calculate a center from all the mesh data (the center will be closer to the denser parts of the mesh, in your case the Suzanne) or it’ll calculate a center from just the bounding box of the entire mesh data. I think this is what you have done. If you want to center all origins, you can just select all your objects then center your 3D cursor and “set origin to 3D cursor”.