[Closed] Can someone help me answer these questions on character animation please

Inbetweening, also known as tweening, is simply the interpolation over time between two key poses. In traditional cel animation, in-betweening was handled by junior animators. They would be assigned to draw the frames that would go in between the key poses drawn by the lead animators.

As for spline vs linear. One is not better than the other. It all depends on your application. For a robotic character, you may want linear interpolation between your keyframes since its movements may need to move at a constant speed. Generally, more organic character animation will lean toward spline interpolation because you can control the easing-in and easing-out into a key frame.

Skeletal animation is simply using a skeleton (a collection of hierarchical nodes) to make a character move. This would be akin to having a physical armature in stop motion animation that is moved and posed. “Root” refers to the top most node in a skeleton. Often times that is the character’s pelvis. Joint is a joint in a skeleton, e.g. an arm or leg. Link is usually a verb that refers to making a node be a child of another node in the hierarchy. E.g. you would link the shin bone to the thigh bone to make it a child of–and thus follow–the thigh bone.

Segmented characters are characters whose mesh geometry moves rigidly with the skeleton. Typically this is done by linking (see above) the mesh directly to the skeleton. Smooth Skinning refers to placing a Skin Modifier on a mesh which allows the mesh to be deform and move with the skeleton. Each vertex in the mesh can be assigned to follow one or multiple bones in a skeleton.

Refer to the Max help on Skinning and Character Animation to get more thorough answers. Watch the video tutorials also.