What approach in animation is described by the principles of straight ahead action and pose to pose?

The approach in animation characterized by the principles of straight ahead action and pose to pose is fundamentally centered around creating movement.

Straight ahead action involves drawing out an animation frame by frame from beginning to end, allowing for fluid, dynamic motion that can capture spontaneous actions and expressions. This technique often lends itself to creating a sense of realism and vitality in scenes where movement is continuous and needs to feel organic.

Pose to pose, on the other hand, focuses on establishing key frames or significant poses and then filling in the sequences in between those key frames. This method is particularly effective for more controlled motion, where the animator can meticulously design the poses to ensure the action adheres to the character’s personality and the story's needs.

Both techniques serve to cultivate a rich sense of movement within an animated sequence. They help animators effectively portray how characters interact with their environment, transition through actions, and express emotions, all of which are critical aspects of animation that contribute to the illusion of life. Thus, the emphasis on these principles is vital for capturing the essence of movement in animated works.