The lighting conditions in your test environment can significantly affect marker detection and tracking.
Make sure that there is enough light in your room or operating environment so that the scene details and marker features are well visible in the camera view. Markers should be viewed under moderately bright and diffuse lighting. The surfaces of the object should be evenly lit. Indoor scenarios generally work well.
If your application use case and scenarios require operating in dark environments, we recommend using the option of enabling the device Flash torch (if your device has one).
Printed marker - flatness
The quality of detecting the marker can degrade significantly when the printed markers are not flat. When designing the physical printouts, game boards, play pieces, try to ensure that the markers do not bend, coil up, and are not creased or wrinkled.
Printed marker - glossiness
Printouts from modern laser printers might also be glossy. Under ambient lighting conditions a glossy surface is not a problem. But under certain angles some light sources, such as a lamp, window, or the sun, can create a glossy reflection that covers up large parts of the original texture of the printout. The reflection can create issues with tracking and detection, since this problem is very similar to partially occluding the marker.
The marker features will be harder to detect and tracking can also be less stable if you are looking at the marker from a very steep angle, or your marker appears very oblique with regard to the camera. When defining your use scenarios, keep in mind that a marker facing the camera whose normal is well aligned with the camera viewing direction, will have a better chance to get detected and tracked.