There are many different kinds of animation. Today, I will focus on 2D animation. You can do Frame-by-Frame animation, Rotoscoping and Cut Out Animation.
1. Frame-by-Frame
You can also call it Flip Animation, Traditional Animation, or Classical Animation. You draw every frame. Ha! Simple, right? Yes, I do. There's another way. You need to first know the frame rate. In this example, it will be 12 frames per second. We will then have to draw 12 images in a second.
You can achieve this with the right timing. You need to start with a test (if animating someone who is jumping then you will need video footage of someone doing so).
There are several ways you can convert the time into frames once you've got your video. Stop Motion Works Stopwatch is my favorite (link located at the bottom of this post). My example will be an 8-frame jump.
You draw key frames for your character's skeleton, then you go on to the frames in between. We'll use a woman jumping as an example (we will only show the actual action and not any anticipation or aftereffects, in order to make it simple). Draw the initial pose (frame 1), then draw the character mid-air in frame 5, and lastly, the landing position (frame 9).
You can now draw the frames in between. Drawing between the starting pose (frame 1), mid-air (frame 5) and landing (frame 9) You draw the frames 3, 7, and 8. Then, draw the frames that are missing. Is it easy? You add details frame-by-frame after the skeleton has been animated. First, you can see a bit more of the body, followed by a detailed head in every frame. Then, the right hand is added to all frames. Continue until every frame has a character.
You are only limited by your imagination. You can make characters do anything you like, with any expression and pose.
Cons: It takes a long time. It can take several hours to animate 1 second.
2. Rotoscoping
Rotoscoping, or frame-byframe animation is another way to create animated videos. You import a video into your 2D animation program. You only need to draw the outline of each frame. You can then replace the drawings you made with details of your character. Big nose? Hair length? Fat? Thin?
It's faster to work with because it doesn't require you to draw key frames, then in between, but rather just each frame. The motion also looks more realistic because the frame-by-frame footage is followed.
Cons Although it is faster, it still takes a long time because it requires you to draw each frame. Also, the character can only act as the actor in the video does.
You can use traditional animation to create the frames if you want to change the video.
3. Cutout Animation
Preparation is required for this type of animation. Cut Out Animation is achieved by "cutting" your character at each of its angles (front, side and back). If you wanted to animate the face, you'd have the hands, arms and forehand in each layer. It takes some time to do this, but you can animate your character like a puppet by preparing only once.
You can animate much faster because it's not necessary to draw every frame. Instead, just draw the character once and then each expression. Once you've finished, you're ready to start kiss anime.
Cons: The character's abilities are limited due to the rig. You can only put the character in positions that you are able to achieve using the rig. It's also not the fastest method of animating, as you have to move the arm and shoulder before you can get to where you need the hand.
4. Inverse Kinematics - Rigged Characters
It is possible to create this type of animation in the shortest time. Toon Boom and Animation Studio offer a variety of tools to help you automate expressions, rig characters with reverse kinematics, or animate facial movements.
The opposite of Forward Kinematics is Inverse Kinematics. (Used in Cut Out Animation). If you want the hand in a certain position when using Cut Out Animation, you must rotate the forearm, shoulder and then the arm. With Inverse Kinematics, you can click and drag the hand to any position. The positions of the arm, shoulder and forearm will be calculated automatically by using mathematical formulas.
Cons: It's very fast. You can animate your images with just a couple of clicks.
Cons: The preparation time is longer than for the cut-out animation but your work hours are reduced exponentially. You are limited to what you can do by the Rig. The character can only be moved into positions that the Rig allows.
Conclusion:
It is impossible to have everything. Either you have unlimited mobility but a huge investment in time, or you only get limited movements with a small investment in time. You have two options. Disney uses frame by frame for their movies, whereas TV shows, due to the tight schedules, use both Rigged Characters as well as Frame by Frame depending on what shot is being worked on.