A high-accuracy visual marker based on a microlens array

Visual markers are useful assistive tool for service robots. Existing planar visual markers have poor accuracy in pose estimation, especially in frontal direction. We solved this problem by a novel principle using a microlens array. The marker displays a changing moiré pattern according to the visual-line direction. We can extract the pose information from the pattern by image processing using a single camera. The developed marker and the processing algorithm enable high-accuracy pose estimation even by observation from frontal direction. We verified its superiority to the conventional method by some validation tests. The marker is an extension of a marker we previously developed, and is more easily fabricated.