Aria Everyday Objects (AEO) World Coordinate Convention

[Carton22]

Hi there,

Thanks for the datasets.

I am utilizing the (x,y,z)position and (w,x,y,z)quaternion of the objects provided in scene_objects.csv in one example sequence inside Aria Digital Twin Datasets, and trying to reconstruct the digital twin virtual environment in Unity.

Can you let me know what is the world coordinate convention in this scene_objects.csv, so that I can convert to Unity right-hand coordinate system and render correctly of the object spatial relationship.

Thank you!

[ja-martinez]

Hi @Carton22 Thank you for reaching out. We'll look into this and get back to you.

[Tarunstk]

Hi @Carton22 the AEO datasets uses the Right Handed Coordinate system with the following axes -

+X - Right
+Y - Up
+Z - Back

following the RUB convention.

Does the unity use the RIght handed coordinate system or the Left handed coordinate system? And if it is right handed, is it RUB (right, up, back) or RUF (Right, up, front) ?

[Carton22]

Hi @Tarunstk,

Thanks for telling me!

Unity uses RUF (Right, up, front).

I am currently trying to figure out how to convert the quaternion in Aria datasets and set the correct Euler Angle in Unity, I have figured out how to convert position, though.

This is the current scene I get after position conversion correctly.

This is the current function I use in Unity for converting, basically I read the position value and quaternion value in the Aria dataset scene_objects.csv

`static Vector3 ConvertPositionToUnity(Vector3 sourcePos)
{
// Source: Aria's coordinate system
return new Vector3(-sourcePos.x, sourcePos.y, sourcePos.z);
}

static Quaternion ConvertRotationToUnity(Quaternion sourceRot)
{
    //  Source: Aria's coordinate system
    return new Quaternion(-sourceRot.x, sourceRot.y, sourceRot.z, sourceRot.w);
}`

Thank you for any help or suggestions in how to reconstruct the scene in Unity using your provided 3D models and their position and rotation values.

Below is the main C# script I use for reconstructing for reference.

Load_all_OBJ.cs

[Tarunstk]

Thanks for the screenshots. I will look into this and get back to you.

[Tarunstk]

Hey @Carton22, I believe the issue is with your conversion functions. Aria uses a right-handed coordinate system where Y points down, while Unity uses Y pointing up.

Your current code negates the wrong components:

Position fix:

// Change from: new Vector3(-sourcePos.x, sourcePos.y, sourcePos.z)
// To:
return new Vector3(sourcePos.x, -sourcePos.y, sourcePos.z);  // Negate Y, not X`

Rotation fix:

// Also note: Aria CSV stores quaternions as (w, x, y, z), not (x, y, z, w)
return new Quaternion(qx, -qy, qz, -qw);  // Negate Y and W components

Make sure you're parsing the CSV quaternion columns in the right order: columns are [5]=qw, [6]=qx, [7]=qy, [8]=qz.

For more details on our coordinate conventions, see: https://facebookresearch.github.io/projectaria_tools/docs/tech_spec/coordinate_convention/3d_coordinate_frame_convention