# Optitrack Calibration Tool

The goal of the Optitrack Calibration is to calculate the relative positions of all the Optitrack Cameras in relationship to each other. 

There are different tools for calibrating multiple optitrack cameras through a wanding process to create one single Optitrack Volume. 

Depending on the type of object that would be used for this wanding process, you would choose the appropriate tool

* Wand Calibration – using a traditional wand with 3 markers on a line a different distnace to each other as the tool for the wanding process.
* Calibration with Rigid Body – using a defined Rigid Body as the tool for the wanding process

### How to Calibrate

{% hint style="info" %}
make sure that there are no noise from other sources that could be confused as a valid marker to the system to ensure good calibration result. If needed, can use the masking function on each of the camera to mask out any areas that is causing problem.
{% endhint %}

* Press the “+” button next to the Recorder section to open up a window for capturing frames for the calibration process.
* Press the “record” button to start the calibration press.
* Press the “record” button again to pause the capturing process.

{% hint style="info" %}
One can toggle to “show overlay” button to display an overlay in the Object Grid to show the coverage of the wanding process per camera.
{% endhint %}

{% hint style="info" %}
It is recommended to disable the “show overlay” option during the actual recording of the wanding process.
{% endhint %}

{% hint style="info" %}
It is recommended that a minimum of 500 valid frames is needed per camera to obtain a good calibration result.
{% endhint %}

* Once the capturing of the data is finished, the recorder window can be closed.
* To run a calibration based on the recording, press the “play” button at the header of the calibration tool. This will take some time to go through all the recorded frames and reconstruct the coordinates of all the optitrack cameras in the volume.

{% hint style="info" %}
For a good calibration result, one should be looking at a projection error of less than 1.0 pixel.
{% endhint %}

* Once this is completed, all of the optitrack cameras should be translated to their relative position with one of the cameras located at the origin point. This can be double checked in the viewport.


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