Digitizing 3D Historical Scientific Instruments with Laser and Photographic Technologies

The Digitization of 3D tangible cultural heritage is becoming a widespread process. It assists in the creation of physical replicas for preserving the original object, for conducting studies, precise documentation and enhanced exhibition, among other purposes. Nevertheless, some objects still present major challenges due to their complex geometry, difficult access, or materials that are not compliant with most acquisition technologies. The Digital Bamberg projected was conducted in collaboration between the Computer Graphics Lab of UFRJ (Universidade Federal do Rio de Janeiro) and MAST (Museu de Astronomia e Ciências Afins), to digitize a historical meridian circle. One of the main goals was to study how 3D scanning technologies behaved when confronted with important challenges, such as: dark and shiny materials (metallic parts), a mechanical instrument, and of historical value (no physical intervention allowed). The digitization process used a laser scanner for geometry acquisition, and high-resolution photographs for appearance retrieval. Most of the challenges were due to the use of these two light-based technologies. The laser, for example, spreads when hitting a metallic surface introducing a high frequency noise, which results in imprecise geometry. Moreover, removing the light influence when taking photographs to acquire the true surface appearance is another critical issue, mainly due to reflections that are difficult to eliminate completely. In this work we discuss the main light-based challenges confronted during this project, as well as solutions to these issues. In a broader sense, the study of light-material interaction is essential to improve digitization techniques, making them more robust, faster, and accessible. In the more specific scenario, this work sheds light on how to efficiently acquire quality geometric and photographic data of complex metallic mechanical instruments, while at the same time, preserving the integrity of the historical object.

@InCollection { MCG16,
  author       = "Marroquim, Ricardo and Coutinho, Daniel and Granato, Marcus",
  title        = "Digitizing 3D Historical Scientific Instruments with Laser and Photographic Technologies",
  booktitle    = "Lights on? Cultural Heritage and Museums!",
  volume       = "1",
  pages        = "193--211",
  year         = "2016",
  editor       = "Paula Menino Homem",
  publisher    = "FLUP Faculty of Arts and Humanities, University of Porto",
  url          = "http://graphics.tudelft.nl/Publications-new/2016/MCG16"
}