The XXI Congress of the International Society for Photogrammetry and Remote Sensing (ISPRS 2008), July 3-11, 2008, Beijing, China
cultural heritage; acquisition; laser scanning; modelling; registration; multi resolution; visualisation
We present the procedure and technologies used to modelling of the Erechtheion at the Acropolis in Athens, a large complex structure with many challenges to data acquisition, processing, and visualisation. We used two scanners, one for medium range high-resolution coverage (1-5 mm lateral data spacing) and one long-range scanner to capture some top sections occluded from the first scanner. We also used high-resolution digital images for image-based reconstruction using Photogrammetric and image matching techniques and for texture mapping. We focus in this paper on the geometric reconstruction from the range sensors. Several issues had to be addressed. Our system must be able to work with data obtained at different resolutions and accuracies and acquired from any viewpoint. The marble surfaces were of different age from one part to another due to decades of restoration. This resulted in different reflectance properties and apparent laser penetration that varied from area to area. Another problem resulted from the huge amount of data. The billions of generated 3D points by all sensors are currently beyond the processing capabilities of commercially available software or hardware. Reducing the data to a manageable size without losing important details had to be addressed.
The XXI Congress of the International Society for Photogrammetry and Remote Sensing (ISPRS 2008) [Proceedings].