Trouble with multi-marker tracking using ARToolkitPlus

Hi there,

I’m working on using ARToolkitPlus in an OpenFrameworks project. I started off using the multiple-markers-demo that Zach Gage posted in this-thread. Anyway, I’ve come across a problem and I’m wondering if anyone else has encountered this. It seems like there might be some reasonable explanation/solution, but its beyond me at the moment.

What I’ve noticed is that when there are multiple markers being tracked, sometimes when one of the markers goes to an extreme angle, it will actually cause another marker to cease to be tracked. If I hold the marker that has stopped being tracked in the same position and then take away the marker at the extreme angle, it starts getting tracked again immediately. I’ve made a video to demonstrate what I’m talking about.

Check it out:

Anyways, it’d be much appreciated if anyone could help me figure out what is going on here. Thanks!