AR trackers can be set up in the AR Trackers window. AR trackers are useful to anchor your augmented reality content to the real world.

You can find the window under Window > AR Trackers.

There are 3 placement (alignment) modes available within WorkLink: Object, Image and Surface Trackers.

AR Tracker types

Object Trackers

Use this tracker type in case you want to anchor your 3D content to a real object in the real world. A prerequisite for this is that you have the 3D data for that real object, so that it can be used by the tracking algorithm to recognize it and place data correctly. More information on how to set up object trackers can be found here.

This article describes how you can create object trackers by selection.

 

Image Trackers

Use this tracker type to align content to a printed image. This tracker type can be useful in case you consistently want to anchor 3D data to the same spot in the real world. 

 

Each surface tracker can be configured with a custom image. If no image is selected, the default Scope image tracker is added, which can be downloaded here. This default tracker, when printed should be 10 cm square, be sure to set the size in the properties to the same size for best tracking results.

When creating your own surface tracker images, we recommend using simple, yet unique, asymmetrical shapes, so they are easy to be picked up, recognized and oriented by the camera feed and the algorithm. Take into account that some camera's, like the one in the HoloLens 2 are quite low resolution for modern standards, focusing on making the image tracker easy to recognize will be helpful with the end user experience. 

Always ensure that the size parameter is the same size as the physical width of the printed target.

Tip: Image tracking on HoloLens 2

Image tracking on HoloLens 2 can require the end user to move quite close to the image tracker, due to its hardware limitations, versus phones or tablets, which have higher resolution cameras. Taken from Microsoft's recommendations, here are some FAQ's around image tracking on HoloLens 2:

• What's the accuracy?
  When detected in a single frame, the size is expected to have at most a 1% error from the actual size. For example, a 10 cm image might be up to +/- 1 mm off in measured size. Under continuous detection, an image's position might drift around by up to +/- 2.5 mm. Once you’ve moved out of detection range, a previous detection's position is up to the mercy of the map error.

• How close do I need to be to the image to detect it?
  On HoloLens 2, for an image varying from 5 cm to 25 cm, the minimum detection distance ranges from 0.25 meters to 0.5 meters. The furthest these can be detected from goes from about 0.5 m for the smallest code to two meters for the bigger.

  For any codes bigger, extrapolate--the detection distance for size increases linearly. For any code smaller, detection simply won’t occur--4-5 cm is the smallest HoloLens can detect.

• Lighting and backdrop
  Image detection quality is susceptible to varying illumination and backdrop.

  Under normal lighting conditions, provide enough contrast and unique identification points in the image for better performance.

Surface Trackers

This mode allows you to align to a surface detected by the app. Once a surface is found, you can tap the device screen to place object once alignment is successful. The anchor point will be exactly located at the intersection of a perpendicular line coming from the center of your device's camera feed, and the detected surface.

Trackers can be deleted by selecting them, and pressing the delete button on your keyboard.

Image guide

Each tracker type has the ability to define an image guide. This can be useful, for example when you want to help the end user find an object in real life, by provide a reference picture of it in context.

As an author, you can define an image, a title and a caption for the reference image, as well as the size of the image.

Display modes

This setting allows you to trigger a specific display or visibility mode when an AR tracker is triggered.

For example, usually it would make sense to use a surface tracker in combination with standalone mode and an object tracker in combination with device mode, in case your project is leveraging hiding and showing objects depending if the viewing mode is intended to display AR content over an existing object.

Defaulting to a surface tracker in app

If you are looking to enforce the Surface Tracker as primary choice, you can enable  "Default Surface Tracker" as shown below: