Augmented Reality for Heritage Tourism Applications: an Efficient Methodology Applied to the Milan Cathedral

Augmented Reality apps for tourism storytelling are evolving, covering diverse topics and objectives. This research defines a fast and effective methodology for developing AR applications for smartphones and tablets by directly using digital survey output. The approach relies on two key concepts: first, employing acquired digital data directly to bypass laborious raw data processing and modelling; second, using a flexible AR system that requires no targets (targetless), images (image tracking), or GPS (geo-positioned AR), making it effective even in complex indoor spaces. The study tests the Immersal SDK System with a mobile mapping system (Leica Geosystem BLK2GO) to establish a digital survey reference for AR positioning. Immersal’s Visual Positioning System (VPS) matches real-time camera images with a spatial map of visual features from a mobile mapping dataset. By identifying key points in real-time images and comparing them with pre-collected data, devices can determine their position and orientation, effectively using the environment as a marker. This solution enables seamless integration of digital content with the real world. The Unity game engine is used to build and customise the AR application. The Milan Cathedral serves as the case study, with designed itineraries tailored to different tourist experiences: a “quick journey” with general cathedral information, an “artistic journey” exploring architecture and art, and a “treasure hunt”. This study highlights AR’s potential to enhance cultural education, engage tourists, and improve heritage management, demonstrating its role in enriching architectural and cultural assets.