# GIS and BIM as Integrated Digital Environments for Modeling and Monitoring of Historic Buildings
## 1 Introduction  
In the field of monument protection, a growing need has emerged for the documentation and visualization of built cultural heritage assets and particularly in relation to their pathology. Various ICT platforms can serve as a tool for this purpose and several efforts have been made in this direction, by the research community, over the last years [1, 2]. Specifically, over the last decade, the integration of multidisciplinary investigation data in combination with the realization of 3D models of historic structures and complex monuments, are included in the standard processes for the assessment of their preservation state. Moreover, regarding the structural documentation of a historic building and its elements' analysis, various steps have been made towards integration of various multidisciplinary data within a finite element model (FEM) for the optimum assessment [3, 4, 5, 6, 7, 8, 9]. Considering the geometric documentation as one of the most important steps towards the documentation of a historic building, many tools are available to obtain such information; however, lately the use of photogrammetric techniques is becoming common practice for the acquisition of a 3D model. Furthermore, extensive efforts have been made in order to combine digital photogrammetry with laser scanning (LS) [10; 11]. In particular, the combination of laser scanning products with high resolution images of materials textures [12; 13] and consequently information regarding material degradation, can lead to the creation of a 3D textured model [14; 15; 16; 17]. Additionally, it is possible to compose a structure from high resolution images through the structure from motion methodology and acquire a digitally reconstructed 3D geometric textured model as well. Overall, the technological advances of 3D scanning and photogrammetry have made the acquisition and representation of spatial data a less time-consuming process. Their products (point clouds and 3d models) can act as blueprints for FEM and, moreover, can assist in the decision making process, for immediate rehabilitation interventions [6; 8; 9]. Another crucial step towards multidisciplinary documentation is the incorporation of historical and architectural archives that can contribute to the structure assessment. Past restoration works documents, or even, knowledge of past restoration interventions are very important issues in the case of a historic building, where its preservation state is linked with the structures' pathology and form. In this framework, the characterization of building materials and the diagnosis of decay patterns can be obtained through the combined use of various nondestructive techniques (NDTs) onsite, and of in-lab analytical techniques after sampling. In particular, through the elaboration of NDTs, information concerning the structure of a building such as type of construction, morphology, masonry thickness, structural alterations through time, as well as areas of past incompatible interventions, cracks and building material loss, can be obtained [18; 19]. Moreover, incorporation of building materials data into FEM is crucial, in order to select compatible restoration materials for intervention actions. Utilizing the products of 3D geometric documentation process, deriving from photogrammetric techniques, is a well-established process for the creation of geographic information system (GIS) thematic maps [20; 21]. In general, the use of GIS platforms addresses to a vast amount of disciplines and scientific fields, nevertheless, in the field of cultural heritage, it still constitutes a research area that has many aspects to unfold [22; 23; 24; 25; 26]. Within this information system, a multilateral database can be created, incorporating diverse data such as historical, architectural, geometrical, and building materials that can be projected through thematic maps. The incorporation of the abovementioned data, within a GIS system, aids towards the life cycle monitoring of the structure under investigation in terms of sustainability [20; 22].