When importing an OBJ it's useful to split up the objects into Blender objects, named according to the OBJ-file. However, this splitting looses the vertex order which is needed when using OBJ-files as morph targets. It also looses any vertices that are not connected to a face, so this must be disabled if you want to keep the vertex order.

As far as Blender is concerned OBJ Objects and Groups are no difference, since they are just two levels of separation, the OBJ groups are not equivalent to Blender groups, so both can optionally be used for splitting.

由于许多应用程序对“向上”使用不同的轴，因此存在轴转换设置，向前轴和向上轴 - 通过将这些轴映射到不同的轴，你可以在应用程序默认的向上和向前轴之间转换。

Blender uses Y Forward, Z Up (since the front view looks along the +Y direction). For example, it's common for applications to use Y as the up axis, in that case -Z Forward, Y Up is needed.