Varjo Markers

Note: you are currently viewing documentation for a beta or an older version of Varjo

Varjo Markers are physical markers tracked by the video pass-through cameras on XR-3 and XR-1 Developer Edition.

Different types of markers can be used for different purposes. As an example, Varjo Markers can be used as cheap replacements for electronic trackers such as Vive Trackers. The cost per printed tracker is significantly lower and the markers require no power to function.

We provide a predefined selection of different marker types and sizes for printing below.

Table of Contents

Object markers

Object markers are used to track static or dynamic objects in the user environment. You can use object markers in both XR and VR applications.

Each marker has a unique ID, and you shouldn’t use the same marker more than once in any given environment. For added precision, an application can use multiple markers to track a single object. You could, for example, track a monitor by placing a marker in each corner.

For SDK-specific examples on using markers, see the Varjo Native SDK and Unity XR SDK pages. We will add an updated Unreal example later on.

Marker Sizes and Tracking Distance

Tracking works best with large markers in general, and especially when the markers are farther away from the headset. Marker sizes and their respective tracking distances are listed below. For best performance, we recommend that you use roughly half the maximum tracking distance.

Marker size Tracking distance
Small Up to 0.5 m (1.5 ft)
Medium Up to 1 m (3 ft)
Large Up to 3 m (9 ft)

Reference marker

The reference marker is used to improve the accuracy of Varjo inside-out tracking (Beta). Read more about using the reference marker.

Only one reference marker can be used at a time, and reference markers are provided in one size only.

Printing Varjo Markers

You can print out Varjo Markers from the PDF documents below:

Marker type Size PDF, A4 size PDF, Letter size
Object marker Small Download Download
Object marker Medium Download Download
Object marker Large Download Download
Reference marker Large Download Download

Printing instructions

  • Use matte paper and matte ink to avoid reflections. Inkjet and pigment printers are suitable, laser toner is not recommended.
  • Print in the darkest and fullest black possible. Rich black (made up of CMYK) is preferable to greyscale (100% K) as the contrast is better for camera recognition.

  • Only print on one side of the paper.

  • Print at 100% scale (“actual size”) with no additional sizing optimizations (i.e., not fit-to-page). To confirm that the sizing is accurate, lay a ruler along the scale on the printout and compare.

  • Cut along the crosses and lines, leaving the white margin around the marker.

  • Ensure that the printed markers are flat and that the paper is not curling.

  • Printing in the wrong size will cause the virtual marker to be be skewed in relation to the physical marker.

Using Varjo Markers

Performance

Currently the Varjo Markers tracking system uses a single CPU core when enabled through the developer API.

Tips

  • Do not bend the markers and always place them on a flat surface. If a marker is curved, its size may be incorrectly detected and positional tracking can suffer.

  • Avoid reflections on your markers to improve tracking.

  • Use more than one object marker to increase tracking accuracy. This is especially useful for tracking a larger area or larger objects, where one marker may not always be in view of the cameras or the object is observed from multiple angles.

  • If an object can be rotated, use markers on all sides of the object. For example, for a large box that will be observed from all sides, place four markers on each side.

FAQ

Q: Can I use Varjo Markers to create objects like tracking cubes? A: Yes, it is possible to group object markers together. This also means that you can create a cube from multiple unique markers. We are working on a way to define marker groups in the API to improve tracking quality.

Q: Can I use Varjo Markers on a curved surface? A: We do not recommend using Varjo Markers on curved surfaces. However, if you need to place a marker on a curved surface, first attach it to something flat (e.g., a piece of cardboard) and then attach that to the surface.

Q: What if my Varjo Markers are printed in the wrong size? A: If your marker is sized incorrectly, tracking for the object will be estimated incorrectly as well. For small markers especially, even a 1 mm (0.03 in) difference in size may cause tracking to shift by about 1 cm (0.3 in).

Q: Positional tracking for my Varjo Markers is unreliable. The virtual objects stutter or don’t stay in one place. A: Check the recommended distances for different marker sizes. Positional tracking may deteriorate at the upper end of the range. We recommend that you choose a larger marker size in such cases.