Cross-domain transferability of deep learning models for building extraction from UAV imagery: a case study and benchmark in Vietnam

- Authors: Dung Trung Pham
Affiliations:
Hanoi University of Mining and Geology, Hanoi, Vietnam
- *Corresponding:This email address is being protected from spambots. You need JavaScript enabled to view it.
- Keywords: Building extraction, Domain gap, DeepLabV3+, UAV imagery, Urban morphology, Vietnam.
- Received: 20th-Jan-2026
- Revised: 8th-Apr-2026
- Accepted: 23rd-Apr-2026
- Online: 1st-Aug-2026
- Section: Geomatics and Land Administration
Abstract:
Automated building extraction from Unmanned Aerial Vehicle (UAV) imagery plays an important role in urban analysis and large-scale geospatial applications. However, models trained on international datasets often struggle when deployed in regions with distinct local urban morphologies. This study evaluates the cross-domain transferability of such models in the Vietnamese urban context. Rather than testing domain adaptation methods, the paper focuses on assessing the performance degradation of source-trained models relative to a localized baseline. Using the DeepLabV3+ architecture with a ResNet-18 backbone, models trained on representative global datasets were evaluated against the HUMG benchmark derived from UAV imagery in Vietnam. The results reveal a pronounced domain gap, with cross-domain Intersection over Union (IoU) values decreasing substantially and reaching as low as 0.642. Error analysis indicates that this degradation is primarily driven by the prevalence of high-density “tube houses,” which frequently cause instance merging and omission errors in non-localized models. In contrast, a model trained in local 10 cm resolution imagery achieved an IoU of 0.857. An efficiency plateau was also observed, whereby approximately 2,000 training samples (40% of the dataset) were sufficient to achieve near-optimal performance at very high resolution. To contextualize these findings within geospatial mapping practice, a simplified geometric model was introduced to explore the potential relationship between IoU and map-scale requirements. However, it is emphasized that overlap-based metrics provide only an indicative assessment and are insufficient to demonstrate regulatory compliance or full geometric validity. Overall, the study highlights the necessity of localized data for reliable building extraction in complex urban environments such as Vietnam.
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