Abstract
Abstract. This work proposes the application of the latest methods of photo-modeling to the study of Gothic architecture in Sardinia. The aim is to consider the versatility and ease of use of such documentation tools in order to study architecture and its ornamental details. The paper illustrates a procedure of integrated survey and restitution, with the purpose to obtain an accurate 3D model of some gothic portals. We combined the contact survey and the photographic survey oriented to the photo-modelling. The software used is 123D Catch by Autodesk an Image Based Modelling (IBM) system available free. It is a web-based application that requires a few simple steps to produce a mesh from a set of not oriented photos. We tested the application on four portals, working at different scale of detail: at first the whole portal and then the different architectural elements that composed it. We were able to model all the elements and to quickly extrapolate simple sections, in order to make a comparison between the moldings, highlighting similarities and differences. Working in different sites at different scale of detail, have allowed us to test the procedure under different conditions of exposure, sunshine, accessibility, degradation of surface, type of material, and with different equipment and operators, showing if the final result could be affected by these factors. We tested a procedure, articulated in a few repeatable steps, that can be applied, with the right corrections and adaptations, to similar cases and/or larger or smaller elements.
Highlights
The study and understanding of architecture occurs through the architectural survey and the resulting graphical summary of what has been observed, measured and examined
We propose a procedure of integrated survey and restitution that will lead to geometric analysis applied to the specific case of gothic portals sited in the centre and in the south of the island, in order to make a comparison between the different decorative and compositional choices followed by manufacturers in the creation of these openings
Visual attractive 3D models could be obtained with the Autodesk Web service, if the objects are not very large and show rotund forms. (Kersten & Stallman 2012) The Autodesk 123D Catch software used in this work operates in cloud computing for the computation of correspondences between the images and the creation of triangulated mesh
Summary
The study and understanding of architecture occurs through the architectural survey and the resulting graphical summary of what has been observed, measured and examined. The software used is 123D Catch by Autodesk an Image Based Modelling (IBM) system available free It combines an app and a web-service. It produces a model from a sequence of photos taken in a very simple way and returns a mesh which must be oriented and scaled in the virtual space. The accuracy of the Image Based Modeling process was compared with similar measurements using laser scanner highlighting the strengths and limitations of the method that is most suitable in the study of contained size elements. In post-production operations, before exporting the mesh to another software that manages and models it, we traced over the model a network of defined points and lines using the tools provided by the software These points are chosen in correspondence with the real ones used during the recording of the reference measurements. We tested the application on a specific case and performed a comparison between various architectural elements, in particular between sections of the mouldings, highlighting similarities and differences, that with other systems, would be long and laborious to obtain
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