This service converts OutSight messages into the A-to-Be object structure.
The A-to-Be format requires specific fields for each object, such as:
- Dimensions - length, width, height
- Local coordinates - of the corner with the smallest coordinate values relative to the ORT tracking camera
- Absolute coordinates - geographic position of the same point as local coordinates
- Speed
- Object ID
- Measurement timestamp
Although OutSight messages contain all necessary information, some fields are not directly available and must be derived.
The following fields are available directly from OutSight messages:
- Object ID
- Measurement timestamp
- Speed
These values are extracted without transformation.
OutSight messages include a bounding box defined in local coordinates. While height is directly available, length and width are not explicitly provided.
To derive length and width:
- Identify the coordinates of the corners of the bounding box.
- Compute distances between corresponding corner pairs for each side.
- Average the distances of opposite sides to obtain consistent length and width values.
This approach assumes that bounding box corners follow a consistent ordering, which seems to be the case.
OutSight and A-to-Be use different reference systems, although both share the same scale.
To compute coordinates:
- Convert OutSight coordinates to ENU (East-North-Up) using the origin defined by the A-to-Be reference system.
- Transform ENU coordinates to A-to-Be local coordinates via matrix multiplication.
- Use the intermediate ENU position to compute absolute geographic coordinates (latitude/longitude) before generating the final local coordinates.
In practice, this process involves two matrix multiplications. While one could combine these into a single transformation, the intermediate ENU values are reused to calculate absolute coordinates efficiently.
| Field | Source |
|---|---|
| Object ID | Direct from OutSight |
| Timestamp | Direct from OutSight |
| Speed | Direct from OutSight |
| Height | From OutSight message |
| Length & Width | Computed from bounding box |
| Local coordinates | Converted via ENU to A-to-Be |
| Absolute coordinates | Derived from ENU |
Notes:
- The conversion assumes consistent bounding box corner ordering.
- Geographic coordinate conversion leverages the ENU intermediate for accuracy and simplicity. There is some distortion associated with this, but at the small scales we are working with it is negligible.