Printable markers for tagging what you photograph on a site visit. Put one in shot and the report knows which room, unit or asset the photo belongs to — no typing on site.
These are ArUco markers, from the augmented-reality library developed at the University of Córdoba. Each carries a number the camera can read reliably at an angle, in poor light, and when partly obscured.
Print on A4, one marker per page, at 100% — not "fit to page", which shrinks the marker and loses the white border around it. That border is part of the marker.