Hello everyone!
I am Jiaju, and I am presenting our work on a layered authoring interface for stylized
3D animations.
This work is done in collaboration with Li-Yi Wei and Rubaiat Habib Kazi.
In the book the Illusion of Life, Disney animators Frank Thomas and Ollie Johnston proposed the
12 principles of animation, which later became an essential component of stylized 2D animations.
As 3D computer graphics develop, there has been significant research and commercial interests
in applying these 12 principles to the 3D animation domain.
However, due to the inherent technical barriers of 3D computer graphics and the complexity
of current commercial animation software, beginners often found it difficult to
apply these 12 principles to animations in 3D efficiently.
In our work, we designed and implemented a tool that helps users, especially novices,
more effectively and efficiently author stylized 3D animations.
When designing the system, our main challenge was to balance between ease of use and expressiveness
In order to better understand the current 3D animation authoring space and gain design
insights, we conducted a design study in which we analyzed state-of-the-art animation tools
and interviewed 6 animation professionals.
Currently, there are three main types of animation authoring paradigms: keyframe-based, procedural-based,
and preset-based.
Keyframe-based software often involves a timeline in which users put down keyframes to drive animations.
In procedural-based tools, you can often see
a node graph through which users can define animation behaviors in a visual programming manner.
Preset-based software presents the user with a set of predefined animations for them to
choose from.
According to our study, keyframe and procedural- based approaches are more flexible in terms
of control and thus are able to create more expressive results.
However, they can be hard to learn and use for novices.
On the other hand, creating with presets can greatly speed up workflow and is beginner-friendly,
but can sometimes be limiting when it comes to flexibility.
In our interviews, one participant summarized the relationships between these various paradigms
and the balance between ease of use and expressiveness into a spectrum like this,
which essentially converts the binary trade-off into a fluid sliding scale.
We are then motivated to combine multiple authoring paradigms to support a wide range
of user needs.
Based on our user study, we formulated 3 design
goals to guide the design of our system The first one is layered authoring interface.
As mentioned before, our main goal is to fluidly balance between ease of use and expressiveness.
Inspired by our study findings, especially the curation to creation spectrum, we wanted
to employ a layered authoring interface by combining multiple authoring paradigms to
harness their respective strengths.
Our second goal is efficiency and modularity.
To help users efficiently create animations, we should provide them with a library of ready-to-use
stylization effects based on the 12 principles of animation.
Moreover, the interactions with these effects should be modular to allow for compositing
for more complex effects Lastly, instead of physically accurate simulation-based
animations, our system should assist users with authoring visually plausible motions
by providing collision information and real-time visualization feedback.
Here I present our stylized 3D animation authoring system that consists of a layered user interface
and a library of preset stylizations.
The layered interface has two levels.
On the surface level, a timeline sequencer with clips arranged in tracks allows the user
to create animations without using keyframes.
Repositioning and resizing these clips controls the timing of each animation.
To help users better coordinate animations with collision events, we also put event markers
on the timeline with detailed information about the collisions.
Each clip in the timeline sequencer is associated with a basic manipulator or a stylization,
whose behavior is defined by our second level authoring interface, the node graph.
By default, the user can use predefined stylizations without the need to work with the node graph.
As they become more comfortable with our tool, they can use the node graph to create custom
stylizations not offered in our library, as shown here in this example.
Our library of preset stylizations consists of motion effects based on the 12 principles
of animation, and each comes with adjustable parameters that allow for fine-tuning.
Here is a showcase of the preset stylizations in the library.
For more details, please refer to our paper and the video figure.
Now let me give you a demo of our system.
We are going to animate this fish swimming around and playing with the ball
First, we create a track and a motion path clip, and then assign the fish object
and a 3D path to move it around.
We then use a similar procedure to animate the ball.
Note that we reverse the second motion path clip here to complete the loop.
We then add an arc clip to deform the fish along the curvy path
We then add a follow through clip to express the soft-bodied nature of the fish.
We adjust the bend factor and bend center parameters to make the effect look more realistic
To emphasize the speed of the fish, we add a staging clip and adjust its appearance parameters
to fine-tune the motion trail
Now let’s work on the collision interactions between the fish and the ball.
We create a new track and add squash and stretch clips.
We only keep the squash clips for the fish.
Using the event markers, we can easily position the squash clips to the right places on the
timeline, and we adjust relevant parameters to make the collision look convincing.
We handle the collisions for the ball in a similar fashion.
In this case, we keep both the stretch and squash clips.
Finally, we add some rotation effects to the ball, and adjust its motion timing for a more
realistic bouncing off look.
We are done!
To evaluate our system, we conducted a user study with 6 participants.
2 of which are professional animators while the other 4 are novices.
Each participant was asked to reproduce two target animations using our system and a tool
of their choice.
The professionals used C4D and the novices all used Blender.
Then, they were given the opportunity to freely create animations with our tool.
Overall, the participants used significantly less time to complete the required animations.
Subjectively, they found our tool to be easier, faster, and more satisfying to use.
They also thought it is somewhat more expressive than the traditional tools.
Here are the animations made by the 6 participants during the open creation session.
Overall, 4 participants made their own custom stylizations with the node graph, and 1 changed
the default anticipation stylization behavior.
P2 and P5 created a custom stylization to add an organic sense of randomness
P6 and P3 used custom effects to bring out the soft-bodied nature of the octopus
P1 and P4 animated the clouds to interact with the environment and other objects more lively
Please refer to our paper and the video figure
for more details on these animations
As part of the user study, we also asked the participants what kind of animations our system
is suitable for creating, and we then created 4 example animations according to their answers.
These animations can be used in areas like education, marketing, and immersive AR experiences.
Thanks so much for your attention.