---
license: apache-2.0
tags:
- motion-inbetweening
- keypose-extraction
- character-animation
- adaptive-interpolation-synthesis
---

## Model Description

This is the AIS-BiLSTM model accompanying the paper:

https://arxiv.org/abs/2605.02742

> Raël et al., "Adaptive Interpolation-Synthesis for Motion In-Betweening on Keyframe-Based Animation",
> SIGGRAPH 2026 Conference Papers (2026)

The AIS-BiLSTM model takes as input a tensor of shape N×(D+1), where N is the number of frames in the sequence and D=596 is the pose dimension. The K input keyposes are placed at their target frame indices in the first D channels, with all other frames zero-filled. The last channel is a binary mask flagging the K keypose positions. The model predicts the full N×D pose sequence.

## Model Details

| Property                 | Value                                                        |
| ------------------------ | ------------------------------------------------------------ |
| Framework                | PyTorch Lightning                                            |
| Checkpoint format        | `.safetensors`                                               |
| Input                    | Masked sequence of shape N×(D+1)                             |
| Output                   | Completed sequence of shape N×D                              |
| Pose dimensionality      | D = 596                                                      |
| Training sequence length | N=224 frames (fixed); variable length supported at inference |
| Frame rate               | 24 fps                                                       |

## Usage

See the [GitHub repository](https://github.com/animaj-lab/mib-ais)

## Training Data

Trained on the `train` split of the [mib_rig_controllers_values](https://huggingface.co/datasets/AnimajSAS/mib_rig_controllers_values) dataset, comprising ~8.1 hours of professionally handcrafted animation at 24 fps.

## Test Data

Evaluated on three test splits of the [mib_rig_controllers_values](https://huggingface.co/datasets/AnimajSAS/mib_rig_controllers_values) dataset:

| Split                       | Schedule       | Description                                                                        |
| --------------------------- | -------------- | ---------------------------------------------------------------------------------- |
| `test_held_out_algorithmic` | DBA            | Held-Out set with a deterministic keypose schedule from the domain-based algorithm |
| `test_held_out_random`      | Random (r=0.9) | Held-Out set with a random keypose schedule                                        |
| `test_production`           | Block          | 5 min production data with ground-truth block keyposes                             |

## License

Apache 2.0