## 5 Conclusions  
Exploring scale issues prior to flight planning for data collection to create 3D geovisualizations in virtual space is essential in 3D mapping. More specifically, for collecting data/images for the 3D mapping of the geosite Voulgaris gorge, the optimal flight altitude was 80 m with 90% front lap and 70% side overlap for the 1:400 cartographic scale. Images collected from a higher altitude (100 m) lead to gaps appearing in the 3D point clouds, and shots from lower height (60 m) did not have enough front and side overlap to create complete 3D point clouds. Increased coverage percentage led to a more significant number of data collected, thus extending the processing time. Additionally, for creating the geosite's 3D model, the images' GSD should be \(\frac{1}{4}\) of the spatial error (10 cm). In this survey, the images' GSD was 2.5 cm which was the most suitable for the 1:400 cartographic scale.  
Also, the panorama's contribution was crucial for visualizing 3D outdoor models, especially in geosites with complex geomorphology such as the Voulgaris gorge. Environmental lights contributed to the uniform light distribution throughout the model, especially in steep and irregular slopes where shading was intense. The transfer of the properly illuminated 3D model with environmental lights calculated from a panorama of the area in an AR environment increased the photorealism of the gorge's geological structure and surrounding area.  
The proposed UAS 3D geovisualization approach results were encouraging as the combination of scale-variant data acquisition flight plans and panoramas could offer an instrumental tool for realistic 3D mapping of geosites. To achieve the large-scale reproducibility of this framework, further research is needed to determine the critical limitations that influence data acquisition, such as sunlight conditions and the associated terrain shading effects.  
Future goals might entail testing this specific methodology in areas with various types of geomorphology. It could also aid in exploring visual variables for the presentation of thematic information in the virtual space and creating contextual geovisualization for the promotion and management of geological sites.  
Conceptualization, E.-E.P., A.P., N.Z. and N.S.; methodology, E.-E.P. and N.S.; software, E.-E.P.; writing--original draft preparation, E.-E.P., A.P. and N.S.; writing--review and editing, all authors. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Research e-Infrastructure \"Interregional Digital Transformation for Culture and Tourism in Aegean Archipelagos\" [Code Number MIS 5047046] which is implemented within the framework of the \"Regional Excellence\" Action of the Operational Program \"Competitiveness, Entrepreneurship and Innovation\". The action was co-funded by the European Regional Development Fund (ERDF) and the Greek State [Partnership Agreement 2014-2020].  
We thank the editor and the three anonymous reviewers for their insightful comments which substantially improved the manuscript. We also thank [PERSON] for his help with AR imaging and [PERSON] for her help with the English language editing.  
The authors declare no conflict of interest.