1. Optimization-based downscaling of satellite-derived isotropic broadband albedo to high resolutionNiko Lukač, Domen Mongus, Marko Bizjak, 2025, original scientific article 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%.
Keywords: isotropic broadband albedo, high-resolution albedo, Sentinel-2 albedo, true orthophoto, anything model, differential evolution
Published in DKUM: 23.04.2025; Views: 0; Downloads: 0
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2. Completely resected stage III melanoma controversy : 15 years of national tertiary centre experienceBarbara Perić, Sara Milićević, Andraž Perhavec, Marko Hočevar, Janez Žgajnar, 2021, original scientific article Abstract: Background: Two prospective randomized studies analysing cutaneous melanoma (CM) patients with sentinel lymph node (SLN) metastases and rapid development of systemic adjuvant therapy have changed our approach to stage III CM treatment. The aim of this study was to compare results of retrospective survival analysis of stage III CM patients% treatment from Slovenian national CM register to leading international clinical guidelines.
Patients and methods: Since 2000, all Slovenian CM patients with primary tumour % TIb are treated at the Institute of Oncology Ljubljana and data are prospectively collected into a national CM registry. A retrospective analysis of 2426 sentinel lymph node (SLN) biopsies and 789 lymphadenectomies performed until 2015 was conducted using Kaplan-Meier survival curves and log-rank tests.
Results: Positive SLN was found in 519/2426 (21.4%) of patients and completion dissection (CLND) was performed in 455 patients. The 5-year overall survival (OS) of CLND group was 58% vs. 47% of metachronous metastases group (MLNM) (p = 0.003). The 5-year OS of patients with lymph node (LN) metastases and unknown primary site (UPM) was 45% vs. 21% of patients with synchronous LN metastasis. Patients with SLN tumour burden < 0.3 mm had 5-year OS similar to SLN negative patients (86% vs. 85%; p = 0.926). The 5-year OS of patients with burden > 1.0 mm was similar to the MLNM group (49% vs. 47%; p = 0.280).
Conclusions: Stage III melanoma patients is a heterogeneous group with significant OS differences. CLND after positive SLNB might still remain a method of treatment for selected patients with stage III.
Keywords: cutaneous melanoma, surgery treatment, sentinel node biopsy, completion lymph node dissection, overall surviva
Published in DKUM: 08.10.2024; Views: 0; Downloads: 2
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3. Graph Neural Network-Based Method of Spatiotemporal Land Cover Mapping Using Satellite ImageryDomen Kavran, Domen Mongus, Borut Žalik, Niko Lukač, 2023, original scientific article Keywords: multispectral, Sentinel-2, superpixel, node, EfficientNetV2, GraphSAGE
Published in DKUM: 23.05.2024; Views: 158; Downloads: 22
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4. Evaluating seagrass meadow dynamics by integrating field-based and remote sensing techniquesDanijel Ivajnšič, Martina Orlando-Bonaca, Daša Donša, Jaša Veno Grujić, Domen Trkov, Borut Mavrič, Lovrenc Lipej, 2022, original scientific article Abstract: Marine phanerogams are considered biological sentinels or indicators since any modification in seagrass meadow distribution and coverage signals negative changes in the marine environment. In recent decades, seagrass meadows have undergone global losses at accelerating rates, and almost one-third of their coverage has disappeared globally. This study focused on the dynamics of seagrass meadows in the northern Adriatic Sea, which is one of the most anthropogenically affected areas in the Mediterranean Sea. Seagrass distribution data and remote sensing products were utilized to identify the stable and dynamic parts of the seagrass ecosystem. Different seagrass species could not be distinguished with the Sentinel-2 (BOA) satellite image. However, results revealed a generally stable seagrass meadow (283.5 Ha) but, on the other hand, a stochastic behavior in seagrass meadow retraction (90.8 Ha) linked to local environmental processes associated with anthropogenic activities or climate change. If systemized, this proposed approach to monitoring seagrass meadow dynamics could be developed as a spatial decision support system for the entire Mediterranean basin. Such a tool could serve as a key element for decision makers in marine protected areas and would potentially support more effective conservation and management actions in these highly productive and important environments.
Keywords: Adriatic Sea, seagrass meadow, change analysis, Cimodocea nodosa, image classifiers, Sentinel-2, marine biology, hydrobiology
Published in DKUM: 17.05.2024; Views: 152; Downloads: 17
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5. Postopek zaznave sprememb rabe zemljišč s časovno analizo podatkov daljinskega zaznavanja : magistrsko deloSašo Ivič, 2024, master's thesis Abstract: Daljinsko zaznavanje je pridobivanje informacij brez fizičnega stika. S pomočjo satelita Sentinel-2, lahko z odbojem elektromagnetnega valovanja pridobimo informacije o površju Zemlje. Preko platforme Copernicus Open Access Hub, ki jo upravlja Evropska vesoljska agencija, lahko brezplačno dostopamo do podatkov satelitov Copernicus od leta 2015 do danes. V magistrskem delu uporabimo satelitske posnetke satelita Sentinel-2, da strojne modele naučimo prepoznavati spremembe na površju Zemlje, v določenem časovnem obdobju. V prvem delu opišemo tehnike daljinskega zaznavanja sprememb na satelitskih slikah. V nadaljevanju opišemo naši dve metodi implementacije zaznave sprememb in ju primerjamo. Ugotovimo, da obe metodi delujeta dobro in s pomočjo modela nevronskih mrež z visoko natančnostjo zaznavata spremembe na površju.
Keywords: Zaznava sprememb, Časovna analiza, Sentinel-2, Daljinsko zaznavanje
Published in DKUM: 01.03.2024; Views: 372; Downloads: 35
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