Sotiris Karavarsamis

Mr. Sotiris Karavarsamis


Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 June 2022 in Sensors
Verified
Journal Article
Open access
PDF file
SKSotiris Karavarsamis
Sotiris Karavarsamis
IGIoanna Gkika
Ioanna Gkika
VGVasileios Gkitsas
Vasileios Gkitsas
KKKonstantinos Konstantoudakis
Konstantinos Konstantoudakis
Dimitrios ZarpalasDimitrios Zarpalas
Dimitrios Zarpalas
This survey article is concerned with the emergence of vision augmentation AI tools for enhancing the situational awareness of first responders (FRs) in rescue operations. More specifically, the article surveys three families of image restoration methods serving the purpose of vision augmentation under adverse weather conditions. These image restoration methods are: (a) deraining; (b) desnowing; (c) dehazing ones. The contribution of this article is a survey of the recent literature on these three problem families, focusing on the utilization of deep learning (DL) models and meeting the requirements of their application in rescue operations. A faceted taxonomy is introduced in past and recent literature including various DL architectures, loss functions and datasets. Although there are multiple surveys on recovering images degraded by natural phenomena, the literature lacks a comprehensive survey focused explicitly on assisting FRs. This paper aims to fill this gap by presenting existing methods in the literature, assessing their suitability for FR applications, and providing insights for future research directions.

6 September 2012
Verified
Conference Paper
Open access
PDF file
SKSotiris Karavarsamis
Sotiris Karavarsamis
IPIoannis Pitas
Ioannis Pitas
NNNikos Ntarmos
Nikos Ntarmos
We present a novel algorithm for discriminating pornographic and assorted benign images, each categorized into semantic subclasses. The algorithm exploits connectedness and coherence properties in skin image regions in order to capture alarming Regions of Interest (ROIs). The technique to identify ROIs in an image employs a region-splitting scheme, in which the image plane is recursively partitioned into quadrants. Splitting is achieved by considering both the accumulation of skin pixels and texture coherence. This processing step is proven to significantly boost the accuracy and reduction of running time demands, even in the presence of sparse noise due to errors attributed to skin segmentation. For detected ROIs, we extract 15 rough color and spatial features computed from the pixels residing in the ROI. A novel classification scheme based on a tree-structured ensemble of strong Random Forest classifiers is also proposed. The method achieves competitive performance both in terms of response time and accuracy when compared to the state-of-the-art.

30 April 2024 in Sensors
Verified
Journal Article
Open access
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DDDennis Dahlke
Dennis Dahlke
PDPetros Drakoulis
Petros Drakoulis
AGAnaida Fernández García
Anaida Fernández García
SKSusanna Kaiser
Susanna Kaiser
SKSotiris Karavarsamis
Sotiris Karavarsamis
Dimitrios ZarpalasDimitrios Zarpalas
Dimitrios Zarpalas
In dynamic and unpredictable environments, the precise localization of first responders and rescuers is crucial for effective incident response. This paper introduces a novel approach leveraging three complementary localization modalities: visual-based, Galileo-based, and inertial-based. Each modality contributes uniquely to the final Fusion tool, facilitating seamless indoor and outdoor localization, offering a robust and accurate localization solution without reliance on pre-existing infrastructure, essential for maintaining responder safety and optimizing operational effectiveness. The visual-based localization method utilizes an RGB camera coupled with a modified implementation of the ORB-SLAM2 method, enabling operation with or without prior area scanning. The Galileo-based localization method employs a lightweight prototype equipped with a high-accuracy GNSS receiver board, tailored to meet the specific needs of first responders. The inertial-based localization method utilizes sensor fusion, primarily leveraging smartphone inertial measurement units, to predict and adjust first responders’ positions incrementally, compensating for the GPS signal attenuation indoors. A comprehensive validation test involving various environmental conditions was carried out to demonstrate the efficacy of the proposed fused localization tool. Our results show that our proposed solution always provides a location regardless of the conditions (indoors, outdoors, etc.), with an overall mean error of 1.73 m.

15 November 2022 in arXiv
Verified
Preprint
Open access
PDF file
SKSotiris Karavarsamis
Sotiris Karavarsamis
ADAlexandros Doumanoglou
Alexandros Doumanoglou
KKKonstantinos Konstantoudakis
Konstantinos Konstantoudakis
Dimitrios ZarpalasDimitrios Zarpalas
Dimitrios Zarpalas
We present the Cross-stitched Multi-task Unified Dual Recursive Network (CMUDRN) model targeting the task of unified deraining and desnowing in a multi-task learning setting. This unified model borrows from the basic Dual Recursive Network (DRN) architecture developed by Cai et al. The proposed model makes use of cross-stitch units that enable multi-task learning across two separate DRN models, each tasked for single image deraining and desnowing, respectively. By fixing cross-stitch units at several layers of basic task-specific DRN networks, we perform multi-task learning over the two separate DRN models. To enable blind image restoration, on top of these structures we employ a simple neural fusion scheme which merges the output of each DRN. The separate task-specific DRN models and the fusion scheme are simultaneously trained by enforcing local and global supervision. Local supervision is applied on the two DRN submodules, and global supervision is applied on the data fusion submodule of the proposed model. Consequently, we both enable feature sharing across task-specific DRN models and control the image restoration behavior of the DRN submodules. An ablation study shows the strength of the hypothesized CMUDRN model, and experiments indicate that its performance is comparable or better than baseline DRN models on the single image deraining and desnowing tasks. Moreover, CMUDRN enables blind image restoration for the two underlying image restoration tasks, by unifying task-specific image restoration pipelines via a naive parametric fusion scheme. The CMUDRN implementation is available at https://github.com/VCL3D/CMUDRN.