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Tracker Coordinate System in Unity

This page describes the world coordinate systems of image, marker, and instant trackers to place a virtual object correctly in Unity.
Please refer to Android, iOS Tracker Coordinate System if you are working on Android or iOS platform.
In Unity, a virtual object will be basically placed along y axis of world coordinate.


Image Tracker

The world coordinate system of Image Tracker is like below.
If the following image is trained by Target Manager and is added in Unity,

ImageTrackerUnity.jpg

the world coordinate is defined, where the x-z plane is set to the image plane and the y axis is set to the direction going through the image like the right figure. imageCoordinateUnity.PNG


Marker Tracker

The world coordinate system of Marker Tracker is like below.
If Marker Trackable is added in Unity,

markerCoodrinate.jpg

the coordinate system of Marker Trackable is shown without a marker image like the left figure.
You need to place a virtual object with considering that the x-z plane is set to the marker plane and the y axis is set to the direction going through the marker like the right figure.


Instant Tracker

The world coordinate system of Instant Tracker is like below.
If Instant Trackable is added in Unity, instantCoordinateUnity.PNG the coordinate system of Instant Trackable is shown like the left figure.
The world coordinate is defined, where the x-z plane is set to the ground plane perpendicular to the gravity direction and the y axis is set to the direction going through the ground plane like the right figure. X axis is set to the direction parallel to a smart phone.


QR Code Tracker

The coordinate system of QR Code Tracker is as follows. When you add QRCodeTrackable to Unity as shown below, the coordinate axis appears.

qrcode_coord_in_unity.jpg qrtracker_unity_coord.JPG

It is set in the world coordinate system with the XZ plane above the QR Code plane and the Y axis with the direction through the QR Code. Therefore, the object to be augmented should be placed with this in mind.