# About the data in EgoExo4D

**URL:** <https://discuss.ego4d-data.org/t/about-the-data-in-egoexo4d/435>\
**Category:** Uncategorized\
**Created:** [December 28, 2023, 5:46am UTC](https://discuss.ego4d-data.org/t/about-the-data-in-egoexo4d/435 "2023-12-28T05:46:51Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![zgchen333](https://avatars.discourse-cdn.com/v4/letter/z/e68b1a/32.png) [@zgchen333](https://discuss.ego4d-data.org/u/zgchen333)\
**Post date:** [December 28, 2023, 5:46am UTC](https://discuss.ego4d-data.org/t/about-the-data-in-egoexo4d/435/1 "2023-12-28T05:46:51Z")

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Hi, EgoExo4D team.

1. Do all videos have the three descriptions `expert commentary`, `narrate-and-act descriptions`, and `atomic action descriptions`? If not, Could you tell me what kind of videos or activities have specific descriptions? (After seeing some examples by the visualizer, I think not all videos have the three descriptions.)

2. Could you offer the cameras’ in/extrinsic parameters and positioning of the cameras about each other? I didn’t find them in the files you provided.

3. What coordinate system is eye\_gaze data in?

4. There may be some small errors in `proficiency_demonstration_train(also val).json`.

```auto
{...
                    "list": NaN,
 ...},

```

In my opinion, maybe it should be modified to

```auto
{...
                    "list": "NaN",
 ...},

```

Thank you so much for your patience.

---

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**Author:** ![miguelmartin](https://avatars.discourse-cdn.com/v4/letter/m/f19dbf/32.png) [@miguelmartin](https://discuss.ego4d-data.org/u/miguelmartin)\
**Post date:** [January 2, 2024, 5:56am UTC](https://discuss.ego4d-data.org/t/about-the-data-in-egoexo4d/435/2 "2024-01-02T05:56:34Z")

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> [@zgchen333](#):
>
> - Do all videos have the three descriptions `expert commentary`, `narrate-and-act descriptions`, and `atomic action descriptions`? If not, Could you tell me what kind of videos or activities have specific descriptions? (After seeing some examples by the visualizer, I think not all videos have the three descriptions.)

No. We aimed to get full coverage, but due to time constraints we were unable to annotate everything.

- Narrate & Act can be identified from the takes.json file, please see [Metadata | EgoExo4D Documentation](https://docs.ego-exo4d-data.org/data/metadata/#takes) for the description of the JSON, it is the `"is_narrated"` field
- Atomic Descriptions: read the JSON file to obtain the set of takes covered, see docs here: [Atomic Action Descriptions | EgoExo4D Documentation](https://docs.ego-exo4d-data.org/annotations/atomic_descriptions/#sample-json)
- Expert Commentary: you will have to read the annotation files similar to above. I will provide more documentation when it is released.

> [@zgchen333](#):
>
> - Could you offer the cameras’ in/extrinsic parameters and positioning of the cameras about each other? I didn’t find them in the files you provided.

For intrinsics&extrinsics, please refer to: [MPS | EgoExo4D Documentation](https://docs.ego-exo4d-data.org/data/mps/#trajectory)

A quote that page:

> - The intrinsic parameters are provided in the `trajectory` directory for the exo-centric GoPro cameras (`gopro_calibs.csv`); for the aria camera it is provided in the capture, or the take-trimmed, VRS file.

* * *

> [@zgchen333](#):
>
> - What coordinate system is eye\_gaze data in?

All 3D data is in the coordinate system for each capture. i.e. the same as the extrinics (trajectory) & point clouds coordinate system. Please read the MPS page for more information: [MPS | EgoExo4D Documentation](https://docs.ego-exo4d-data.org/data/mps/)

* * *

> [@zgchen333](#):
>
> 1. There may be some small errors in `proficiency_demonstration_train(also val).json`.

cc @srama2512 as POC for proficiency

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<div class="post-metadata">

**Author:** ![srama2512](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@srama2512](https://discuss.ego4d-data.org/u/srama2512)\
**Post date:** [January 4, 2024, 7:47am UTC](https://discuss.ego4d-data.org/t/about-the-data-in-egoexo4d/435/3 "2024-01-04T07:47:19Z")

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> 1. There may be some small errors in `proficiency_demonstration_train(also val).json`.

@zgchen333 - Thanks for pointing out the above. This was a post-processing artifact of reading empty fields in csv files. I think an appropriate way to handle this is to replace Nan with an empty list. We will fix this in our next release.

---

<div class="post-metadata">

**Author:** ![zgchen333](https://avatars.discourse-cdn.com/v4/letter/z/e68b1a/32.png) [@zgchen333](https://discuss.ego4d-data.org/u/zgchen333)\
**Post date:** [January 5, 2024, 3:36am UTC](https://discuss.ego4d-data.org/t/about-the-data-in-egoexo4d/435/4 "2024-01-05T03:36:25Z")

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Okay, I understand. Thank you for your reply.