3D Scanning in Arts & Culture
In the course of history, mankind has created great artwork. We have to preserve this heritage for our present as well as for our future generations. Therefore, the significance of digital imaging and documentation of these masterpieces has been continuously growing - be it in the field of architecture, fine arts or archaeology in general.
Print
Scanning with an optoTOP-HE system
in the Antalya Museum, Turkey
3D Modelling of the "Weary Herakles" Statue
This application describes the digitisation project of the famed "Weary Herakles" statue, on display in the Antalya Archaeological Museum in Turkey.
Project Definition
Around 330-320 BC, the Greek master Lysippos of Sikyon created a larger than life-sized (said to be nearly 3m) bronze statue of the Greek demi-god Herakles. Because of his rare posture of repose, it is referred to as the “Weary Herakles” statue.
One particular replica made of marble was found in two parts in geographically opposite areas of the world. To date, time and circumstances for the damage are not resolved. It is said to be carved in the Hadrianic or Antonine (Roman) period.
The upper half of this “Herakles Farnese type” statue was first discovered in the USA in the early 1980s. It is currently on display in the Boston Museum of Fine Arts. The lower part was found by Prof. Jale Inan at an excavation site in Perge (Antalya, Turkey) in 1980. It is now on display in the Antalya Museum, along with a photograph of the top half.
Since upper and lower parts are to date geographically separated, the objective of the scanning project was to digitally record and model both parts of the statue and combine these digital models in the computer with the intention that at least this way a complete statue could be seen, appreciated and analysed. With the help of the Turkish authorities and the Antalya Museum, the project members were able to complete the work on the lower part. However, access to the Boston Museum for digitisation of the upper part was – and to date has been – denied.
Measuring System
The digitisation of the lower part of the statue was carried out in September 2005 in the Antalya Archeological Museum. A Breuckmann optoTOP-HE, a high-definition topometrical 3D white-light (coded structured light) scanner system, kindly provided by Breuckmann’s sales partner in Turkey, InfoTRON Co. (Istanbul) was used for the scanning task.
This measuring system allows the three-dimensional digitisation of art objects and paintings at a very high level of resolution and accuracy. Optionally, the texture and/or the colour of the object can be recorded, offering a one-to-one representation of 3D coordinates and their respective colour information.
The recording time for a single scan is about 1 second for a 1.4 Mpixel camera. Different scans can be directly aligned by means of the 3D geometry of the digitised object without using any additional markers.
In order to achieve the best high-definition digitisation result of the lower statue part,
a sensor with a 1.4 Mpixel camera and a FOV of about 480 x 360 millimeter was chosen, resulting in a lateral resolution of approximately 360 µm and a depth resolution of
about 20 µm.
With Breuckmann's software OPTOCAT, the recorded 3D data can be visualised in shaded form, optionally with overlapping texture or colour information, and stored in standard file formats, such as STL or PLY.
Result
Active sensors, e.g. laser scanners and structured light systems are used for many kinds of 3D object reconstruction tasks, one important area of which being the 3D documentation of cultural heritage objects. Active sensing with structured light systems is a mature technology and allows high resolution documentation of cultural heritage objects.
The system has acquired high-quality point cloud data of the statue. The processing results with an accuracy level of about 50 µm fully complied with the performance requirements of the system. The most active user involvement is required in the editing steps of the project,
in particular for filling in remaining data holes caused by the inaccessibility of some areas for the scanner’s ‘eyes’ due to the complex geometry of the measuring object.
Various software packages have been used to carry out the modeling steps, each of which featuring its own particular functions and advantages. An integrated package, providing all features required for sophisticated and automatic editing
tasks, is to date not available.
Pictures
- The project team
- Evaluation back side
- Scanning process
- Evaluation side view
- 3D digitisation on site
