Something seems to be wrong with my model and I can't figure it out

Question

I recently started learning blender and made my first model. When I try importing my model to unreal engine I have all kinds of weird problems seemingly with scale and rotation.

When I tried to apply location and rotation (I was told that might fix the exporting issues) the mirroring would break.

Apply rotation made one half of the model rotate 180° while the other half stayed in place.

Apply location made the 2 halves of my model move apart without disconnecting. The connection between them just stretched.

After manually fixing these things by rotating the entire model 90° and moving the 2 halves closer together, I was able to apply transformations without anything breaking.

I thought that fixed my issue but today I found out about Mixamo. I uploaded my model and made Mixamo generate a new rig for it (it wouldn't accept my rig probably because it had a tail.) Mixamo was able to apply it's animations to my model just fine and I downloaded the newly rigged model plus animations.

Now when I reimport the model into blender it's fingers are curled backwards, whenever I enter edit mode the entire model spins 90°, and trying to apply transformations moves it a couple meters to the side.

Now I can probably fix these things manually again but I assume this is caused by some overarching problem with my model and I would like to fix it completely before things go wrong again.

Thank you!

Answer 1

The mirror modifier (which I assume you are using) works in relation to the origin of your model (the orange dot). When you apply location and your model isn't on world origin you are moving the model origin to the world origin (if that makes sense lol). Effectively you are moving the mirror to X 0.000 Y 0.000 Z 0.000. When using the mirror modifier the origin of the object has to be between the real and mirrored half. If you are creating an asset for unreal just keep the model in the middle of the world or don't apply transform before applying the mirror modifier.

The model spinning when you enter edit mode is caused by the rig/animation. When you enter edit mode the model ignores all keyframes for the animation and goes to it's default position. This is fine and it is supposed to happen.

Applying transformations is the same, your model probably has location keyframes from mixamo and that causes the weird behaviour. I usually try not to mess with meshes after they have been rigged it almost always causes problems (especially when you don't really know what you are doing)