# Adjusting Global Origin for Tracking Bars

{% hint style="info" %}
The OptiTrack Duo/Trio tracking bars are factory calibrated and there is **no need to calibrate the cameras** to use the system. By default, the tracking volume is set at the center origin of the cameras and the axis are oriented so that Z-axis is forward, Y-axis is up, X-axis is left.
{% endhint %}

## Tracking Bar Coordinate System

If you wish to change the location and orientation of the global axis, you can use the ground plane tools from the [Calibration pane](https://v30.wiki.optitrack.com/index.php?title=Calibration) and use a Rigid Body or a calibration square to set the global origin.

![Default coordinate axis for the Trio tracking bar](https://content.gitbook.com/content/GaZwzcsVav6zPBRZpapU/blobs/pw5Pepr9klQKOPi8vOFT/image.png) ![Default coordinate axis for the Duo tracking bar.](https://content.gitbook.com/content/GaZwzcsVav6zPBRZpapU/blobs/m6N747deaM6mte4YmM1l/image.png)

## Coordinate Systems Tool

When using the Duo/Trio tracking bars, you can set the coordinate origin at the desired location and orientation using either a Rigid Body or a [calibration square](https://docs.optitrack.com/motive/calibration/calibration-squares) as a reference point. Using a calibration square will allow you to set the origin more accurately. You can also use a custom calibration square to set this.

**Adjustig the Coordinate System Steps**

1. First set place the calibration square at the desired origin. If you are using a Rigid Body, its [pivot point](https://docs.optitrack.com/motive/rigid-body-tracking) position and orientation will be used as the reference.
2. **\[Motive]** Open the [Calibration pane](https://docs.optitrack.com/motive/calibration).
3. **\[Motive]** Open the *Ground Planes* page.
4. **\[Motive]** Select the type of calibration square that will be used as a reference to set the global origin. Set it to Auto if you are using a calibration square from us. If you are using a Rigid Body, select the Rigid Body option from the drop-down menu. If you are using a [custom calibration square](https://docs.optitrack.com/motive/calibration), you will need to set the vertical offset also.
5. **\[Motive]** Select the Calibration square markers or the Rigid Body markers from the [Perspective View pane](https://docs.optitrack.com/motive-ui-panes/viewport)
6. **\[Motive]** Click Set **Set Ground Plane** button, and the global origin will be adjusted.

![Ground plane page for adjusting global origin from the Calibration pane.](https://content.gitbook.com/content/GaZwzcsVav6zPBRZpapU/blobs/QLbGsBwSrqcOvPGG4FEh/image.png)

![Calibration square axis convention.](https://content.gitbook.com/content/GaZwzcsVav6zPBRZpapU/blobs/p9rXeV6CAnYaIYSZBYvl/image.png)