---
dataset_info:
  features:
  - name: created_at
    dtype: string
  - name: sequence
    sequence:
      sequence: float64
  - name: width
    dtype: float64
  - name: height
    dtype: float64
  - name: preview_image
    dtype: image
  - name: num_points
    dtype: int64
  - name: duration
    dtype: float64
  - name: avg_force
    dtype: float64
  - name: min_force
    dtype: float64
  - name: max_force
    dtype: float64
  - name: avg_altitude
    dtype: float64
  - name: min_altitude
    dtype: float64
  - name: max_altitude
    dtype: float64
  - name: avg_azimuth_sin
    dtype: float64
  - name: min_azimuth_sin
    dtype: float64
  - name: max_azimuth_sin
    dtype: float64
  - name: avg_azimuth_cos
    dtype: float64
  - name: min_azimuth_cos
    dtype: float64
  - name: max_azimuth_cos
    dtype: float64
  - name: signer
    dtype: string
  splits:
  - name: train
    num_bytes: 10848294.0
    num_examples: 137
  download_size: 8296862
  dataset_size: 10848294.0
configs:
- config_name: default
  data_files:
  - split: train
    path: data/train-*
extra_gated_description: Due to the consent forms we use, we cannot share the dataset
  with others. But we may be able to help other researchers seek permission from the
  signatories.
extra_gated_fields:
  Country: country
  Institution: text
  I want to use this dataset for: text
---

# SignSeq Dataset

The **SignSeq** dataset contains time-series handwriting signature traces collected at 240 Hz by Apple Pencil on iPad. Each example records the full stroke sequence along with per-stroke metadata and a rendered preview image. Intended use cases include signature generation, style analysis, and handwriting modelling.

## Features

Each record contains the following fields:

| Field             | Type                       | Description                                                                                                          |
|-------------------|----------------------------|----------------------------------------------------------------------------------------------------------------------|
| `created_at`      | `string`                   | ISO-8601 timestamp of recording start.                                                                               |
| `sequence`        | `sequence<sequence<float>>`| A list of points: each `[t, x_rel, y_rel, force, altitude, azimuth_sin, azimuth_cos]`.                               |
| `width`           | `float64`                  | Original signature width. Used to de-normalize `x_rel` back to pixel coordinates.                                     |
| `height`          | `float64`                  | Original signature height. Used to de-normalize `y_rel` back to pixel coordinates.                                    |
| `preview_image`   | `image`                    | PNG rendering of the full signature trace.                                                                            |
| `num_points`      | `int64`                    | Total number of captured points in `sequence`.                                                                        |
| `duration`        | `float64`                  | Recording duration in seconds.                                                                                        |
| `avg_force`       | `float64`                  | Mean pen pressure over the signature.                                                                                 |
| `min_force`       | `float64`                  | Minimum pen pressure.                                                                                                 |
| `max_force`       | `float64`                  | Maximum pen pressure.                                                                                                 |
| `avg_altitude`    | `float64`                  | Mean pen altitude angle (radians).                                                                                    |
| `min_altitude`    | `float64`                  | Minimum pen altitude angle (radians).                                                                                 |
| `max_altitude`    | `float64`                  | Maximum pen altitude angle (radians).                                                                                 |
| `avg_azimuth_sin` | `float64`                  | Mean sine of pen azimuth angle (radians).                                                                             |
| `min_azimuth_sin` | `float64`                  | Minimum sine of pen azimuth angle (radians).                                                                          |
| `max_azimuth_sin` | `float64`                  | Maximum sine of pen azimuth angle (radians).                                                                          |
| `avg_azimuth_cos` | `float64`                  | Mean cosine of pen azimuth angle (radians).                                                                           |
| `min_azimuth_cos` | `float64`                  | Minimum cosine of pen azimuth angle (radians).                                                                        |
| `max_azimuth_cos` | `float64`                  | Maximum cosine of pen azimuth angle (radians).                                                                        |
| `signer`          | `string`                   | Anonymized signer identifier.                                                                                         |

### Notes on `sequence`

- **Element breakdown**  
  1. `t` : Relative timestamp in seconds (starts at `0.0` for the first point).  
  2. `x_rel`, `y_rel` : Relative coordinates in [0, 1], to be multiplied by `width`/`height` to recover pixel positions.  
  3. `force` : Pen pressure (unitless).  
  4. `altitude` : Pen altitude angle in **radians**.  
  5. `azimuth_sin`, `azimuth_cos` : Sine and cosine of pen azimuth angle in **radians**.