# CalTrack

*CalTrack* is a feature exclusive to primitive objects, video screens, and imported 3D objects. It allows you to visualize the location of environment trackers through the responsive movement of the chosen Viewport Object.

One possible use case is projection mapping on a moving object as demonstrated in the video below:

{% embed url="<https://youtu.be/YSUf7uPQFvg?si=s2jRQTpyG6W6kyLI>" %}

## CalTrack Setup

To apply the transformation of incoming tracking device data to an Object, all you have to do is follow three simple steps:

1. Insert an Object onto the Viewport,
2. choose a *Tracking d*evice,
3. place at least three different *Tracking points* on the Object, and
4. assign the *Trackers* to the *Tracking points*.

### 1. Place an Object onto the Viewport

In the Viewport window, choose a *Primitive* object, *Video Screen*, or imported *3D Object* from the *Toolbar* and drag it to the desired spot on the Viewport floor.

In reality, here, you will want to place the virtual twin of the physical 3D Object you will be tracking.

<figure><img src="/files/34eJhgesLiX4aVklLdbg" alt=""><figcaption></figcaption></figure>

### 2. Choose a Tracking Device

In **Tracker device** dropdown menu in *CalTrack* collapsible section, you can choose one of the *Device receiver* nodes placed in the Devices window.

<div align="left"><figure><img src="/files/PDfG4KpCLxbL2j0NhZXb" alt=""><figcaption></figcaption></figure></div>

### 3. Select three different points from that Object

Next, you need to choose at least three different points on the virtual Object that match the position of the physical Trackers, in relation to the physical 3D Object.

To do so, under the *CalTrack* section click on **Add point** button. Upon clicking, you will enter a special mode, indicated by the **Pick a point** label on the top left corner of the Viewport window.

{% hint style="info" %}
**Good to know:** In the *Pick a point* mode, the chosen Viewport Object will be isolated and all other Viewport objects will become invisible.
{% endhint %}

If **Render spheres** checkbox is enabled, anytime you hover over the chosen object, a sphere will be drawn out.

To add a point to the object, all you have to do is click on it.

<figure><img src="/files/8kf29gmgnbk8f6qbZsEI" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}
Good to know: You can also exit the *Pick a point* mode without adding any points by pressing **ESC** key or **left-clicking** somewhere else in the Viewport.
{% endhint %}

### 4. Assign the Trackers to the points

Under the *Tracker* column, enter the name of the physical tracker for each corresponding point.

Once you enable the **Apply transformation override** checkbox, the virtual Object will jump to the position in the Viewport that matches the position of the physical Object in your tracking environment.

<figure><img src="/files/oU0a5g52c9HQYrIDFe6L" alt=""><figcaption></figcaption></figure>

{% hint style="warning" %}
If LightAct is not able to find a suitable transformation of the Viewport object based on the tracking data, it won't be able to move the object. This for example happens if tracking points are not correctly paired with physical trackers.
{% endhint %}


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