Innovative LiDAR/TLS 3D scanning method
LiDAR works by emitting laser pulses and measuring the time they take to return (time of flight) from scanned surfaces, which generates a dense 3D point cloud (a spatial dataset with x, y, and z coordinates).
“TLS technology offers high accuracy but is costly and challenging to operate inside caves, because these surveys require setting the scanners in fixed positions,” says Antón. “Smartphone LiDAR, built into devices like the latest generations of ‘Pro’ iPhones, has a shorter range (up to 5 meters) and lower accuracy, but it is portable, affordable, and produces textured 3D meshes in real time. By validating smartphone scans against TLS and total station data, we evaluated its reliability for cave archaeology.”
The researchers scanned key sectors of La Pileta Cave, including the “Gran Pez” chamber, using both a TLS (Leica Geosystems’ BLK360 G1) and an Apple iPhone 15 Pro with LiDAR apps (Polycam, MetaScan, 3D Scanner App).
“Each smartphone scan covered from 2 to 3 meters, which required systematic overlap and controlled lighting,” Antón explains. “The resulting models were aligned with topographic (total station) control points and compared against the TLS point cloud, used as a benchmark for the iPhone’s data. Fieldwork took several days, while post-processing and validation required weeks of analysis.”
The most striking moment of this work for Antón was realizing how a simple smartphone could capture the iconic Gran Pez and surrounding paintings in remarkable detail to produce textured models that rival professional systems in visual quality.
“Just as powerful were the sensations of being inside La Pileta itself,” he says. “Looking over the edge of the Gran Sima, a vast abyss that feels truly impossible for the untrained visitor, or seeing the completed iPhone survey as a whole, with its intricate network of galleries, dramatic vertical drops, and the human figure placed at the cave entrance for scale, made the experience both humbling and unforgettable.”