3D can be used as a basis to make shots a bit more clear and easier to understand when the storyboard is too rough.
Sometimes for more complex scenes, real people are used as reference for the movements. While this can give the animators an idea of performance, it’s still hard to imagine it from different angles and perspectives.
To make the steps more efficient and reduce the time thinking while increasing the time for making, a rough 3D model can help. A 3D artist will take the reference footage and focus on the movement of the performer. After that some camera adjustments according to the instructions of the storyboard are made and also some basic planes for the background are created. This result is called previsualisation. It gives a rough idea of how the final product will look like. Even motion tracking can be used for this, which gives the animator even more accurate reference material. The animators can use the original reference footage and the previs to create something that is accurate to the original performance but also has its own value as an original animation. This will help the animator, but it is still just reference. The real magic comes of course later as a result of the animators technique.