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I'm new to Blender and purchased a course on Udemy--"Complete Blender Creator: Learn 3D modelling for Beginners". I'm having a hard time wrapping my head around "Rotate & Scale" "Apply an objects transformation to it's data". I know how to do it, but the instructor doesn't go into much detail. What is it's purpose? Would someone mind explaining it to me like I'm five?

Thanks

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  • $\begingroup$ You might consider adding some more detail to your question. Remember, a lot of people reading/answering your question will not have seen that course (or any Udemy course), and definitely won't consider paying and spending the time watching it just to answer your question. $\endgroup$
    – Nathan
    Jun 10, 2021 at 23:09
  • $\begingroup$ Some info about Delta Transforms here - oneminutevideotutorials.com/2014/12/29/… $\endgroup$
    – Christopher Bennett
    Jun 10, 2021 at 23:15
  • $\begingroup$ You said "Apply an objects transformation to it's date" did you happen to mean data and not date? $\endgroup$
    – Ron Jensen
    Jun 11, 2021 at 0:19

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To get your head round CtrlA applying transforms, I think it helps to separate the ideas of an 'object' and its 'mesh' (vertices). You can think of the object as a vehicle for its mesh.

Here's an object (the yellow axes,) sitting on the World Origin. Its mesh is a cube.

enter image description here

The numbers show the coordinates of the mesh vertices.

(To visualize an object, as here, you can switch on 'Axis' in its Object Properties tab, Viewport Display panel.)

Now here's the same object, translated a bit, rotated a bit, and scaled in Y, in Object Mode.

enter image description here

All the vertex coordinates are the same as they were before! Their locations are measured along the object axes; in the Object Space. It's the object which has been transformed. The axes have been moved,rotated and scaled. See how the Y axis has been stretched. Measured along those axes, the vertices are exactly where they were before.

Changing the locations of the vertices with respect to the object is what you do in Edit Mode. In Object Mode, you transform the whole object, and the object carries the mesh along with it.

Here are the locations of the vertices in World Space, (along the eternally fixed World axes) That is: the object-space locations of the vertices, with the further transform of the object added in:

enter image description here

CtrlA applying (all) the transforms of the object is baking the transforms of the object into its mesh, and returning the object to the World Origin:

enter image description here

You can apply the transforms individually, too.. applying rotation will align the object to the world, leaving its location where it was.. applying scale will return the object axes to length 1, and compensate in the coordinates of its vertices.. applying translation will return the object to the World origin, leaving its mesh behind.

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  • $\begingroup$ great explanation!! $\endgroup$
    – Chris
    Jun 23, 2021 at 9:28
  • $\begingroup$ @Chris Thanks! It's hard to know, when you're a bit too familiar. People who can clearly remember their own confusion give better explanations. ( Also, IMO, the reason artists make some of their most exciting work when they're thrashing about a bit, and haven't quite learned how to use their tools. The great artists have learned how to forget.. :D ) $\endgroup$
    – Robin Betts ♦
    Jun 23, 2021 at 9:46
  • $\begingroup$ YOU MADE MY DAY!!!!!! 😂😂😂😂😂😂 $\endgroup$
    – Chris
    Jun 23, 2021 at 9:52
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If you click "N" key, a bar will appear on the right side of blender. If you go to "Item" (with an object selected), you can see the location, rotation and scale values. When you apply scale, he changes the "Scale" values to 1 without changing the objects size. When you apply rotation, he changes the "Rotation" values to 0, without actually rotating the object.

Is this what you wanted to know?

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  • $\begingroup$ Applying a transform alters the local data coordinates Eg default cube has a corner at (1, 1, 1) locally, which if object scaled by (4, 4, 4) that corner coordinate is global location (4, 4, 4). If I apply scale to the object scale is (1, 1, 1) and the local coordinate of the corner is (4, 4, 4) ie the scale has been applied to the cube making it now a 4 times larger mesh than default cube at unit scale. The global location of the corners remain unchanged. Feel the "answer" given above simply adds to confusion... $\endgroup$
    – batFINGER
    Jun 11, 2021 at 18:05
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I think "date" is a typo for "data".

In object mode, select an object. A fast way of getting to the menu is control+A.

A wheel of options are opened such as "apply all", "apply scale", etc.

Before many operations in Blender, it is important to do this. You should get used to doing this all the time. It affects the smooth operation of modifiers and textures.

I don't understand the exact reasons for this, although it has do with many of the operations depending on the objects having a scale of 1 as the basis for various bits of code. As you know, 3D programs depend on real world scale to make calculations. So, when you start with the wrong scale it makes the math more complicated. This can happen easily during modelling as you readjust the dimensions of the object to be correct.

The solutions to this is that, once you are satisfied with the dimensions of the object you can apply scale.

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