Question regarding world frame and orientation

Software
1

Hi,

I have a question regarding the world frame defined in zed-sdk/positional tracking at master · stereolabs/zed-sdk · GitHub . I thought it is defined as the camera frame when the camera started, so I would expect the orientation for the camera in the beginning w.r.t. the world frame is always an identity matrix. But it seemed to be changing depending on the pose when the camera was started, e.g., the orientation when the camera was started looking at the ceiling is not an identity. Why does the orientation change?

Best regards,

Chuan

2

Hi @Huang-Chuan,

Please take a look into our official documentation on positional tracking here: Positional Tracking Overview - Stereolabs, as well as our page on coordinate frames.

The behavior you are seeing is due to the parameter PositionalTrackingParameters.set_gravity_as_origin, which overrides the initial position of the camera to match the gravity given by the IMU

You can set this parameter to false if you wish to disable this behavior