---
title: "Vector Constraint"
url: "https://help.maxon.net/c4d/en-us/Content/html/TPHCONSTRAINTVECTOR.html"
section_path: "Motion Tracker > Motion Tracker Tags > Vector Constraint"
element_id: "TPHCONSTRAINTVECTOR"
command_id: "1029909"
description: "This page documents the Vector Constraint tag for motion tracking in Cinema 4D. Two features define an axis and, crucially, a real-world length — giving …"
---

# Vector Constraint

> **Note:** **What is it about?**
>
> This page documents the **Vector Constraint tag** for motion tracking in **Cinema 4D**. Two features define an axis and, crucially, a real-world length — giving the reconstruction its correct scale so 3D objects match the footage's dimensions.

> **Tip:** Tip:This tag only works after a 3D features have been generated, i.e., a 3D reconstruction has taken place.

Using this tag, one of the vertex cluster's axes can be bound to the world or Object Tracker coordinate system and - even more importantly - the scaling of the vertex cluster can be defined.

Use the tag as follows to calibrate (2 methods):

- Create the tag for the respective **Motion Tracker** or Object Tracker object. An axis with handles at each end will appear at the center of the Viewport. Drag these handles onto 2 Tracks or 2 features, respectively, that should be used to define the world or object axis:

  ![Image: 038372.jpg](https://help.maxon.net/c4d/en-us/Content/Resources/Images/038372.jpg)

As soon as the axis is defined in the tag's settings, the vertex cluster will be oriented accordingly. The value entered for **Length** (i.e., the actual real-world length, e.g., 100 cm for a table edge) will scale the points accordingly.

- Select the **Create Vector Constraint** tool (main menu Tracker | Constraints and click on the desired Track. A Vector Constraint tag with a linked Null object that matches the Track will be created automatically.

[Here you will find](https://help.maxon.net/c4d/en-us/Content/html/53374.html.md) an example scene with an assigned tag.

Create Vector Constraint

This command creates a Vector Constraint tag with a matching linked feature (see previous paragraph).