# GIS and BIM as Integrated Digital Environments for Modeling and Monitoring of Historic Buildings
## 4 Discussion  
Through the 2D and 3D documentation of the decay patters concerning structural flaws and damages, within a GIS and BIM environment, qualitative and quantitative results were depicted and presented. Diagrams including information regarding the extent and the range of the cracks and detachment of building materials in relation with their location on the building were developed, additionally including information of the environmental parameters and the construction phases. More specifically, the decay factors that prevail in the structure of the building in terms of cracks and loss of building material are presented through a diagram (Figure 21) deriving from the 2D GIS analysis. A high percentage in the length of the cracks was observed, mainly in the west and south facade with 62% and 72% side to side cracks respectively, thus assisting in the conclusion that the additional expansions of the historic building were of lower quality structure compared to the first construction phase. In addition, the capillary cracks prevail in the east facade, causing only superficial decay, indicating the cohesive structure of the first construction phase. Figure 20: Workflow indicating the proposed process towards HBIM creation and integration. When assessing cracks, the width of the crack is often more important than the length of the crack. In Figure 22, a slight alteration is observed in terms of quantifying the area that each crack holds, indicating that the width of the side to side cracks are larger than their length, thus providing additional qualitative information regarding the structure's state of preservation. Although the higher percent of decay in terms of cracks' length is observed in the south facade, the percentage grows even higher when the area of the cracks is computed. In addition, the cracks are concentrated on the structure of the southwest construction phase, with the eminent side to side crack to divide the different masonries of the south, in the two construction phases. This implies that although the masonry of the 2 nd construction phase has similarities with the initial structure, there is no interlocking between the masonries. In the west facade, where the latter construction phases of the building are encountered, there is a large percentage of side to side cracking, concentrated in the masonry of the 3 rd construction phase. This can be justified by the masonry-type, which is a limestone, mortar structure in the southwest of the  
Figure 21: Diagram illustrating the percentage of the length of each type of crack (m) for all facades of the building. Figure 22: Diagram illustrating the percentage of the area (m\({}^{2}\)) each type of crack possesses for all facades of the building. wall (2 nd C. Ph. ), while brick-walls prevail in the upper part of the northwest (3 rd C. Ph.). This decay pattern is also supported by the building material analysis, where the bricks of the 3 rd construction phase presented micro-fractures and cracks and the building materials as a whole where of lower quality, compared to the building materials of 1 st and 2 nd construction phase. Moreover, quantitative information regarding the extent of the cracks, in a 3D environment, including volumetric information, can be acquired. Quantification of the cracks within the HBIM environment was accomplished by converting the 2D data features in 3D volumetric elements. Processing of these data, results in valuable information regarding the preservation state of the structure, since the computation of the percentage of cracking in each wall can be acquired, thus providing information for refurbishment works. In Figure 23, the volumetric representation of the cracks indicates the need for immediate actions in order to achieve an adequate level of structural integrity, especially in the south and west sides of the historic building.