| Title: | Optimization-based downscaling of satellite-derived isotropic broadband albedo to high resolution |
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| Authors: | ID Lukač, Niko (Author)
ID Mongus, Domen (Author)
ID Bizjak, Marko (Author) |
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| Files: |  remotesensing-17-01366-v3.pdf (20,47 MB)
MD5: C00CA5A2336AB4E4374519E84B440A0A
 https://www.mdpi.com/2072-4292/17/8/1366
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| Language: | English |
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| Work type: | Article |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: | FERI - Faculty of Electrical Engineering and Computer Science
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| Abstract: | 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 km2 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%. |
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| Keywords: | isotropic broadband albedo, high-resolution albedo, Sentinel-2 albedo, true orthophoto, anything model, differential evolution |
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| Publication status: | Published |
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| Publication version: | Version of Record |
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| Submitted for review: | 28.02.2025 |
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| Article acceptance date: | 10.04.2025 |
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| Publication date: | 11.04.2025 |
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| Publisher: | MDPI |
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| Year of publishing: | 2025 |
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| Number of pages: | 26 str. |
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| Numbering: | vol. 17, no. 8, [article no.] 1366 |
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| PID: | 20.500.12556/DKUM-92603  |
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| UDC: | 004.9 |
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| ISSN on article: | 2072-4292 |
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| COBISS.SI-ID: | 232486915 |
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| DOI: | 10.3390/rs17081366 |
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| Copyright: | © 2025 by the authors |
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| Publication date in DKUM: | 23.04.2025 |
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| Views: | 141 |
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| Downloads: | 5 |
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| Metadata: |    |
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| Categories: | Misc.
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