Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High Resolution
In this paper, a novel method for estimating high-resolution isotropic broadband albedo is proposed, by downscaling satellite-derived albedo using an optimization approach. At first, broadband albedo is calculated from the lower-resolution multispectral satellite image using standard narrow-to-broad...
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MDPI AG
2025-04-01
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| author | Niko Lukač Domen Mongus Marko Bizjak |
| author_facet | Niko Lukač Domen Mongus Marko Bizjak |
| author_sort | Niko Lukač |
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| description | In this paper, a novel method for estimating high-resolution isotropic broadband albedo is proposed, by downscaling satellite-derived albedo using an optimization approach. At first, broadband albedo is calculated from the lower-resolution multispectral satellite image using standard narrow-to-broadband (NTB) conversion, where the surfaces are considered Lambertian with isotropic reflectance. The high-resolution true orthophoto for the same location is segmented with the deep learning-based Segment Anything Model (SAM), and the resulting segments are refined with a classified digital surface model (cDSM) to exclude small transient objects. Afterwards, the remaining segments are grouped using K-means clustering, by considering orthophoto-visible (VIS) and near-infrared (NIR) bands. These segments present surfaces with similar materials and underlying reflectance properties. Next, the Differential Evolution (DE) optimization algorithm is applied to approximate albedo values to these segments so that their spatial aggregate matches the coarse-resolution satellite albedo, by proposing two novel objective functions. Extensive experiments considering different DE parameters over an 0.75 km<sup>2</sup> large urban area in Maribor, Slovenia, have been carried out, where Sentinel-2 Level-2A NTB-derived albedo was downscaled to 1 m spatial resolution. Looking at the performed spatiospectral analysis, the proposed method achieved absolute differences of 0.09 per VIS band and below 0.18 per NIR band, in comparison to lower-resolution NTB-derived albedo. Moreover, the proposed method achieved a root mean square error (RMSE) of 0.0179 and a mean absolute percentage error (MAPE) of 4.0299% against ground truth broadband albedo annotations of characteristic materials in the given urban area. The proposed method outperformed the Enhanced Super-Resolution Generative Adversarial Networks (ESRGANs), which achieved an RMSE of 0.0285 and an MAPE of 9.2778%, and the Blind Super-Resolution Generative Adversarial Network (BSRGAN), which achieved an RMSE of 0.0341 and an MAPE of 12.3104%. |
| format | Article |
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| institution | OA Journals |
| issn | 2072-4292 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | MDPI AG |
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| series | Remote Sensing |
| spelling | doaj-art-81bf103d9aee46648f9a08b79db8521d2025-08-20T02:28:25ZengMDPI AGRemote Sensing2072-42922025-04-01178136610.3390/rs17081366Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High ResolutionNiko Lukač0Domen Mongus1Marko Bizjak2Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, SloveniaFaculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, SloveniaFaculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, SloveniaIn this paper, a novel method for estimating high-resolution isotropic broadband albedo is proposed, by downscaling satellite-derived albedo using an optimization approach. At first, broadband albedo is calculated from the lower-resolution multispectral satellite image using standard narrow-to-broadband (NTB) conversion, where the surfaces are considered Lambertian with isotropic reflectance. The high-resolution true orthophoto for the same location is segmented with the deep learning-based Segment Anything Model (SAM), and the resulting segments are refined with a classified digital surface model (cDSM) to exclude small transient objects. Afterwards, the remaining segments are grouped using K-means clustering, by considering orthophoto-visible (VIS) and near-infrared (NIR) bands. These segments present surfaces with similar materials and underlying reflectance properties. Next, the Differential Evolution (DE) optimization algorithm is applied to approximate albedo values to these segments so that their spatial aggregate matches the coarse-resolution satellite albedo, by proposing two novel objective functions. Extensive experiments considering different DE parameters over an 0.75 km<sup>2</sup> large urban area in Maribor, Slovenia, have been carried out, where Sentinel-2 Level-2A NTB-derived albedo was downscaled to 1 m spatial resolution. Looking at the performed spatiospectral analysis, the proposed method achieved absolute differences of 0.09 per VIS band and below 0.18 per NIR band, in comparison to lower-resolution NTB-derived albedo. Moreover, the proposed method achieved a root mean square error (RMSE) of 0.0179 and a mean absolute percentage error (MAPE) of 4.0299% against ground truth broadband albedo annotations of characteristic materials in the given urban area. The proposed method outperformed the Enhanced Super-Resolution Generative Adversarial Networks (ESRGANs), which achieved an RMSE of 0.0285 and an MAPE of 9.2778%, and the Blind Super-Resolution Generative Adversarial Network (BSRGAN), which achieved an RMSE of 0.0341 and an MAPE of 12.3104%.https://www.mdpi.com/2072-4292/17/8/1366isotropic broadband albedohigh-resolution albedoSentinel-2 albedotrue orthophotoSegment Anything ModelDifferential Evolution |
| spellingShingle | Niko Lukač Domen Mongus Marko Bizjak Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High Resolution Remote Sensing isotropic broadband albedo high-resolution albedo Sentinel-2 albedo true orthophoto Segment Anything Model Differential Evolution |
| title | Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High Resolution |
| title_full | Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High Resolution |
| title_fullStr | Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High Resolution |
| title_full_unstemmed | Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High Resolution |
| title_short | Optimization-Based Downscaling of Satellite-Derived Isotropic Broadband Albedo to High Resolution |
| title_sort | optimization based downscaling of satellite derived isotropic broadband albedo to high resolution |
| topic | isotropic broadband albedo high-resolution albedo Sentinel-2 albedo true orthophoto Segment Anything Model Differential Evolution |
| url | https://www.mdpi.com/2072-4292/17/8/1366 |
| work_keys_str_mv | AT nikolukac optimizationbaseddownscalingofsatellitederivedisotropicbroadbandalbedotohighresolution AT domenmongus optimizationbaseddownscalingofsatellitederivedisotropicbroadbandalbedotohighresolution AT markobizjak optimizationbaseddownscalingofsatellitederivedisotropicbroadbandalbedotohighresolution |