Collection of palaeontologic types in the Museo Geologico Giovanni Capellini. Creation of digital data base on morphometries acquired with 3D survey technologies for the study of fossils

The Museo Geologico Giovanni Capellini has a large palaeontologic collection accumulated over many centuries; it includes valuable type material. This collection is of paramount scientific and historical importance. In order to promote open and easy access to such material a cooperative project with the DIAPReM Center has been recently developed aimed at digitizing of this natural heritage. The research objective is to create a digital data base always available on-line. It is being organized in different layers, in order to facilitate new research approaches for specialists globally and, moreover, to increase popularity for visitors and users of the Museum. Three-dimensional models, obtained by 3D laser scanninng technologies as well as related photographic data are collected in a computerized data base. This allows consultation of the assembled data as well as simultaneous entering of new data. The morphometric and dimensional variety of the digitalized types has determined the use of different methodologies of survey, in order to obtain maximum accuracy, management and usefulness of models produced. The biggest palaeonthologic types are acquired by time of flight laser scanner technology (Leica HDS 3000) and represented by a cloud-points model. The smallest types are been acquired by an optical triangulation survey instrument (Vivid-I 900, Konica Minolta), a technology that works with the factors of the tenth of a millimetre and therefore offers significant potential in description of reality. In this second case, the result consists of a mesh, a closed surface. In both cases the model obtained is a three-dimensional morphometric model: it hasn’t any holes ant it is navigable in three dimensional space. The Mesopithecus Pentelici survey is presented as a case study. The model was obtained by an optical triangulation laser scanner. The mathematical three-dimensional model, certified by a specific accuracy degree in respect to instrument technical specifics, is presented as a set of mathematical coordinates x, y, z. Anyone can query the model subsequently. The methodological approach makes a clear distinction between the time of survey and querying the data at a subsequent time; it is necessary to set a purpose relation to link the two major times of the knowledge process of the survey project. The raw data survey can be regarded as a geometric element with a great deal of data. However it has to be interpreted on a quality level according to the nature of the representation. It is a selective path for achieving a systematic reduction of the geometrical information by means of a mathematic algorithm or by a critical decision by the operator. Details visible with difficulty for a normal observer can now be studied and also enlarged: superficial and volumetric variation in the specimen is tied to the three-dimensional mathematical information. Through information created by the three-dimensional high-density survey, the path of investigation of the object of survey allows drawing from 3D data base lines or surfaces in order to build a descriptive synthesis tailored to the representation required. In particular it is possible to section the 3D data base according to plans chosen by the user in order to visualize a specific detail, to filter data, so they have different density, to draw different sections from every point and according to whatever orientation is desired. This allows generation of a cognitive process that can also be developed backwards. This system allows repeating and checking the method during a file research, something that was not previously possible - obtaining a section of a fossil required physical sacrifice of a specimen, the palaeontologist having to cut and measure it. It was possible to carry out a limited number of sections; this contrasts with the multiplicity of sections now possible. Moreover the digital datum allows saving of all steps in the process, sections as well as measurement and data storage for subsequent research checking and/or more profound investigation. Finally digitizing a specimen reduces problems of accessibility. Directly from home, a natural scientist can carry out all kind s of measurements, without having to go to where the fossil is preserved and, least of all, having to physically reach, even using a scaffold, the vertebrate he wishes to study.