## 2 Research Aims, Materials, and Method
### Methodology
#### 2.2.1 Terminology Definition  
To be able to \"normalise\" the results from the two batches that might appear heterogeneous and make them comparable, it was necessary to build a common terminology of reference. We have referred to this phase as **\"Step 0: Terminology definition\"**. On one hand, for the definition of damages and type of heritage, we have referred to the official UNESCO terminology based on a two-tier system of damaging factors consisting of a list of 14 primary hazards from which more than 150 types of hazards (secondary) derive ([[https://whc.unesco.org/en/factors/](https://whc.unesco.org/en/factors/)]([https://whc.unesco.org/en/factors/](https://whc.unesco.org/en/factors/)), accessed on 15 April 2023) [24]. The UNESCO terminology is nowadays the most complete and shared document regarding the definition of heritage hazards, and all types of damage considered by the papers analyzed in the present research fit well with either UNESCO's primary or secondary hazards. To have a statistically significant sample, we considered the 14 primary factors proposed by the UNESCO report [24] to be sufficiently exhaustive. In fact, if we had also considered the secondary factors, we would not have obtained a statistically significant result. For each paper selected, we normalized the types of damaging factors described according to the UNESCO terminology, so as to produce a coherent dataset to be analysed.  
Figure 1: Literature assessment: overall methodology workflow.  
On the other hand, for a definition of the terminology of geomatics technologies employed, we built a nomenclature reference, as presented in Figure 2. To provide a comprehensive list of technologies and their sub-categories, we have referred to the current structure adopted by the International Society of Photogrammetry and Remote Sensing (ISPRS). The list of commissions and sub-commissions of the ISPRS was hence used to define a structure and correlations between different technologies, sensors, and their future technological perspectives within a specific applications framework of the monitoring of cultural heritage and cultural landscapes.  
Some adaptations were required. In addition to the list of geomatics technologies, it was necessary to indicate \"Machine Learning/Artificial Intelligence (AI)\" as possible relevant terms for this exercise.  
At the same time, \"Photography\", from either Aerial or UAV platforms (but also balloon or other specific types), was taken into account as a relevant term because the use of photographs from above has been a common practice by CH professionals for several decades. Similarly, the use of satellite imagery consultation within maps' search engines without further processing of the images themselves (e.g., through Google Earth or Bing) was considered under the general term \"Engine\". Both examples were used for literature assessment (Step 1, Data collection and literature assessment), as they indicate awareness of technological potential and specifically that of satellite imagery. However, articles from the scientific literature and documents from the Grey literature that only mentioned this kind of practice without a specific reference to actual data processing or ways to further process and analyze satellite images were not considered in order to answer question 1. The concept is that the simple mention of maps' search engines cannot be taken as proof that this technology is effectively exploited in daily practice. Similar consideration was made for any other RS reported in Figure 2, and, in that case, the textual occurrence was disregarded to the scope of the final statistics of the present assessment.  
The time period of the scientific and Grey literature analyzed in this study spans from 2000 to 2022, thus providing a sufficiently long timeline to assess trends and current perspectives.  
Figure 2: Terminology for remote sensing technologies.