## 4 Results
### Height Validation: Empirical Assessment of PSInSAR Data Accuracy in the Hanyang District  
Figure 12 presents a comparative analysis of 2018 height measurements and validation data collected in March 2024 against the GHSL data of 2018 and PSInSAR results. To facilitate direct comparison, we firstly resampled GHSL and validation data to 50 m resolution, then we categorized our height and validation data into the same five segments used by GHSL: the first category encompasses heights of 3 m or less; the second ranges from 3 to 6 m; the third span 6 to 15 m; the fourth extends from 15 to 30 m; and the fifth includes buildings with heights greater than 30 m.  
Figure 12a displays the GHSL data, which illustrates a diverse distribution of building heights. There is a significant presence of taller structures in the \"15-30 m\" and \">30 m\" categories, suggesting that GHSL captures a wide range of building heights. However, the considerable number of buildings in the \"6-15 m\" range points to a certain level of generalization in GHSL's depiction of urban structures, which, while comprehensive, may not always capture the precise heights of buildings.  
Figure 12b focuses on the PSInSAR data, which predominantly categorizes buildings exceeding 30 m in height. This indicates PSInSAR's high sensitivity and precision in identifying tall urban structures, making it particularly suitable for precise elevation mapping. The PSInSAR data's emphasis on taller buildings highlights its utility in urban areas characterized by high-rise architecture.  
Figure 12c shows the validation data, which supports the accuracy of the PSinSAR results, with a substantial number of buildings also classified in the \">30 m\" category. This alignment confirms PSinSAR's effectiveness and suggests it provides a more accurate reflection of the current urban landscape compared to GHSL, especially in the detection of taller buildings.  
Comparing these datasets, Figure 12d,e highlight the differences in height estimation between GHSL and PSinSAR when validated against actual measurements from aerial surveys. GHSL, while valuable for broad urban studies, tends to underestimate the height of taller buildings. In contrast, PSinSAR shows a closer alignment with the validation data, particularly in the accurate detection of structures taller than 30 m. The validation data corroborate the accuracy of the PSinSAR results by also highlighting a substantial frequency of buildings in the \">30 m\" category. This validation supports PSinSAR accuracy and suggests a closer alignment with the real-world scenario than GHSL. Although the validation  
Figure 12: Height values and distribution for **(a)** GHSL, **(b)** Standard PSinSAR results, and **(c)** Validation data (obtained by aerial survey using DJI Maxic 3 Pro). Comparison between **(d)** GHSL vs. Validation data and **(e)** PSinSAR vs. Validation. The latter histograms are displayed with the same height classes along the x-axis for comparability, while a different scale is used along the y-axis to highlight the respective height correctness and over-/under-estimations per each height class.  
data also show buildings in the \"6-15 m\" and \"15-30 m\" categories, the quantity is less pronounced than in GHSL, indicating a partial but not complete agreement.  
In summary, when these results are compared, PSInSAR height estimates align more closely with the validation data, particularly in the detection of taller structures. GHSL data, while valuable, appears to offer a broader perspective that may include some underestimation of the tallest buildings.