## 6 Conclusions  
This study presented and validated an effective PSInSAR stack processing methodology for quantifying VUG using a dense, 8-year-long COSMO-SkyMed SAR dataset over Wuhan, China. Our approach successfully adapted interferometric techniques, traditionally used for stable targets, to monitor the dynamic process of vertical construction, addressing challenges like data gaps and evolving scatterers. The analysis revealed significant VUG in Wuhan between 2012 and 2020, characterized by intense high-rise development in central districts like Hanyang, Wuchang, and Hongshan, while peripheral areas showed more moderate growth. This multi-temporal, high-resolution perspective offered detailed insights into the spatial heterogeneity and dynamics of Wuhan's vertical expansion, surpassing the capabilities of traditional 2D remote sensing or static global datasets. Validation against high-resolution drone data confirmed the method's ability to estimate building heights accurately, particularly for structures exceeding 30 m height, though GHSL data showed limitations in capturing the tallest buildings. While the methodology marks a significant step forward, inherent limitations in PSInSAR, such as the potential misplacement of scatterers on non-rooftop elements leading to height underestimation and the impact of residual noise, require acknowledgment. Future efforts aimed at refining scatterer selection, mitigating noise, and potentially integrating complementary datasets could further enhance the precision of VUG monitoring. Nonetheless, this research demonstrates the considerable value of advanced SAR interferometry techniques for providing critical analysis to understand and manage the complex three-dimensional growth of modern cities.  
Conceptualization, Z.A., T.B., F.C. and D.T.; formal analysis, Z.A.; funding acquisition, T.B.; investigation, Z.A.; resources, T.B., F.C. and D.T.; supervision, T.B.; visualization, Z.A.; writing\(-\)original draft, Z.A.; writing\(-\)review and editing, Z.A., T.B., F.C. and D.T. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China under Grant 42250610212.  
The data that support the findings of this study are available from the Italian Space Agency\(-\)ASI (information about the COSMO-SkyMed Mission and data exploitation and access are available at: [[https://www.asiit/en/earth-science/cosmo-skymed/](https://www.asiit/en/earth-science/cosmo-skymed/)]([https://www.asiit/en/earth-science/cosmo-skymed/](https://www.asiit/en/earth-science/cosmo-skymed/)), accessed on 25 May 2025). However, restrictions apply to the availability of the data, which were used under license for the current study, and, thus, are not publicly available.  
This research was carried out using COSMO-SkyMed\({}^{\circledR}\) Products \(\copyright\) of the Italian Space Agency (ASI), delivered under a license for use by ASI (i.e., \"WUHAN-CSK\" led by [PERSON]).  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.