3-D Modelling and Visualization of Stone Inscription using Close Range Photogrammetry - A case study of Hero-stone

Stone Inscriptions and archaeological structures are an asset to humankind, which contains the history of the past. Estampage is the traditional method used to obtain the replica of the Inscriptions which were primarily used to decrypt the text and for documentation purposes. Presently, Close-Range Photogrammetry (CRP) is a useful remote sensing technique to digitalize these Inscriptions for study as well as preservation. The current study focuses on the creation of a 3-D model of the Hero-Stone using digital camera technology. The photographs were acquired using a Sony Alpha7 III camera with a 35mm full-frame CMOS sensor. 261 images/frames were acquired from different heights above ground and with various positions and angles about the stone inscription to cover it all around. The data acquired from the mirrorless camera was processed in a series of steps which includes image matching, dense point cloud generation, mesh reconstruction and texturing of the model. As the sensor is non-metric, two markers acquired from the field were added to the scene for scaling it accurately. The processed model has 10,915,514 facets (TIN) and 8000 x 8000 x 4 textures providing a realistic appearance. The recent developments in computer vision using the Structure from Motion (SfM) approach enables the reconstruction of the Hero-Stone accurately with realistic textures and details useful for preservation works.