PoBiTag: Toward Unobtrusive and Customizable Tag-Based Interaction With Optical Polarization and Birefringence

Traditional tag-based interaction systems often rely on visible codes such as QR codes or barcodes, which can disrupt the visual design of printed media, particularly in content-dense or space-limited environments. This work introduces PoBiTag, a visually unobtrusive tagging system that uses common transparent and birefringent materials (e.g., PET stickers or cellophane tape) as tags. This tag design allows users to embed tags on any surface of interest without compromising their visual aesthetics. To enable accurate and convenient tag scanning, PoBiTag enhances tag visibility based on optical phenomena including polarization and birefringence. It converts a mobile device’s camera and torch into polarized optical components by attaching polarizing films. This enables illumination and capture of tagged surfaces under polarized light, making birefringent regions visually distinguishable from others and thus allowing accurate tag segmentation and identification. Experiments with real-world users demonstrate that PoBiTag significantly reduces tag-scanning time, even on complex or glossy surfaces, while achieving a high tag identification accuracy of 96.5% on average. These results confirm PoBiTag’s practicality for diverse real-world tag-based interaction scenarios, such as interactive books.