## 5 Discussion  
The proposed methodological approach underlines how UES classification and representation within a 3D GIS-based environment can support the processes of evaluation, planning, and monitoring by improving the visualisation of the spatial relationships of service allocation. Figure 8: 3D visualisation of Regulation (green), Carrier (blue), and Information (red) service values with Jenks natural breaks categorisation. The overlay allows for visualising trade-offs among services at an overall level. Figure 7: 3D visualisation of Carrier Services values with Jenks natural breaks categorisation. The colour gradient and histogram height show high (green) and low (red) UES values. The 3D GIS-based modelling in the case study was intended to explain how certain information can be communicated more effectively, improving the level and quality of knowledge of decision-makers regarding the localisation, features, and status of UES. The identification of UES and the classification of relevant spatial functions allowed us to define a framework for structuring site-specific knowledge through the selection of services representing local peculiarities. The integration of GIS and MCDA supported the implementation of spatial assessments to investigate the UES and their relationships within the characteristics of the city system, referred to as MMU [43], which was used to identify a homogenous surface for analysis [42]. The elaboration of a Spatial Decision-Making Support System (SDMSS), in which GIS tools and the spatial multi-criteria AHP method interact and work together, produced a normalised index of UES per MMU. The processing of the cell-by-cell weighted sum and Euclidean distance among the spatial elements provided a relevant result to integrate different UES characteristics. At the same time, the number of the objects within the distance threshold and their weighted sum provided the weight per category per cell and was used to express the importance of the cell with respect to the Regulation, Carrier, and Information functions. According to [PERSON] and [PERSON] [100], the selection of different statistical units leads to totally different results, generating new patterns and spatial relationships between the features that shape the investigation area. An advantage of using a regular cell grid is combining the original mapping units with more accurate cells, in order to investigate the effects of urban changes at different scales. Indeed, the EEA has recognised that regular grids are very useful for understanding the spatial variability of phenomena, their mapping, and their evaluation [101]. Within the SDMSS, the implementation of MASCOT (based on the AHP multi-criteria aggregation rules) identified the potential to map the distribution of UES for each Regulation, Carrier, and Information function, as well as that to assess the multi-functionality levels. Indeed, MASCOT provided the opportunity to operationalise the pairwise comparison between different tiers and to spatially express the evaluation results. The 3D visualisation of the spatial distribution of UES represents an innovative component of the methodological process, making the values of the three selected UES functions categories more easily understandable and communicable. The 3D visualisation can be considered a suitable way to analyse UES characteristics and to support the elaboration of planning and design alternatives, starting with the identification of enabling conditions. Our experimental study, applied to the city of Naples, made it possible to verify the significance of the role that 3D modelling can play in a virtual decision environment, in terms of the communication of UES, as well as the democratisation and the negotiation of transformational choices [53]. The 3D modelling and virtual decisional environment involve the representation of UES, considering an inclusive approach in which all the involved stakeholders have the chance to understand the spatial changes in UES and to elicit values related to each understanding jointly.