How do I find global rotation values of a child object? Object1 is a child of Object2. I rotated Object2 thus rotating Object1. In the Transform section of the N panel Rotation values of Object1 are 0,0,0. How do I get global values of rotation of Object1 related to world?

This may seem trivial when you have only 2 objects, but actually I have a chain of child-parent relations, each one rotated by some degree. Calculating this by hand would take ages.

I need to align rotation of the object that is not part of this child-parent chain with the object that is.
Add a Copy Rotation constraint to the object you want to rotate. In constraint panel, set Target to that child object;
After seeing it being aligned well, CtrlA >  Visual Transform;
Delete that constraint, since you don't need it anymore.




Edit:

If you just want to "know" the global rotation info, you can simply AltP > Clear and Keep Transformation, then you will see the visual rotation applied, which is the global rotation. After getting what you want, you can simply CtrlZ to undo.