Leonidas Sakalauskas

Dr. Leonidas Sakalauskas

Institute of Data Science &amp, Digital Technologies, Vilnius University, 01513 Vilnius, Italy

Research Focus & Metrics

Academic Career Length

23Years (2004-Present)

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

Representative Publications

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5 January 2022 in Applied Sciences
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DPDarius Plikynas
Darius Plikynas
AIAudrius Indriulionis
Audrius Indriulionis
ALAlgirdas Laukaitis
Algirdas Laukaitis
LSLeonidas Sakalauskas
Leonidas Sakalauskas
This paper presents an approach to enhance electronic traveling aids (ETAs) for people who are blind and severely visually impaired (BSVI) using indoor orientation and guided navigation by employing social outsourcing of indoor route mapping and assistance processes. This type of approach is necessary because GPS does not work well, and infrastructural investments are absent or too costly to install for indoor navigation. Our approach proposes the prior outsourcing of vision-based recordings of indoor routes from an online network of seeing volunteers, who gather and constantly update a web cloud database of indoor routes using specialized sensory equipment and web services. Computational intelligence-based algorithms process sensory data and prepare them for BSVI usage. In this way, people who are BSVI can obtain ready-to-use access to the indoor routes database. This type of service has not previously been offered in such a setting. Specialized wearable sensory ETA equipment, depth cameras, smartphones, computer vision algorithms, tactile and audio interfaces, and computational intelligence algorithms are employed for that matter. The integration of semantic data of points of interest (such as stairs, doors, WC, entrances/exits) and evacuation schemes could make the proposed approach even more attractive to BVSI users. Presented approach crowdsources volunteers’ real-time online help for complex navigational situations using a mobile app, a live video stream from BSVI wearable cameras, and digitalized maps of buildings’ evacuation schemes.

2 June 2020 in Informatica
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RKRasa Karbauskaitė
Rasa Karbauskaitė
LSLeonidas Sakalauskas
Leonidas Sakalauskas
GDGintautas Dzemyda
Gintautas Dzemyda
Publisher: Vilnius University Institute of Data Science and Digital Technologies, Journal: Informatica, Title: Kriging Predictor for Facial Emotion Recognition Using Numerical Proximities of Human Emotions, Authors: Rasa Karbauskaitė, Leonidas Sakalauskas, Gintautas Dzemyda , Emotion recognition from facial expressions has gained much interest over the last few decades. In the literature, the common approach, used for facial emotion recognition (FER), consists of these steps: image pre-processing, face detection, facial feature extraction, and facial expression classification (recognition). We have developed a method for FER that is absolutely different from this common approach. Our method is based on the dimensional model of emotions as well as on using the kriging predictor of Fractional Brownian Vector Field. The classification problem, related to the recognition of facial emotions, is formulated and solved. The relationship of different emotions is estimated by expert psychologists by putting different emotions as the points on the plane. The goal is to get an estimate of a new picture emotion on the plane by kriging and determine which emotion, identified by psychologists, is the closest one. Seven basic emotions (Joy, Sadness, Surprise, Disgust, Anger, Fear, and Neutral) have been chosen. The accuracy of classification into seven classes has been obtained approximately 50%, if we make a decision on the basis of the closest basic emotion. It has been ascertained that the kriging predictor is suitable for facial emotion recognition in the case of small sets of pictures. More sophisticated classification strategies may increase the accuracy, when grouping of the basic emotions is applied.

12 March 2020 in Annals of Operations Research
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RDRuta Dadeliene
Ruta Dadeliene
SDStanislav Dadelo
Stanislav Dadelo
NPNatalija Pozniak
Natalija Pozniak
LSLeonidas Sakalauskas
Leonidas Sakalauskas

1 January 2004 in Informatica
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LSLeonidas Sakalauskas
Leonidas Sakalauskas
Publisher: Vilnius University Institute of Data Science and Digital Technologies, Journal: Informatica, Title: Application of the Monte‐Carlo Method to Nonlinear Stochastic Optimization with Linear Constraints, Authors: Leonidas Sakalauskas , We consider a problem of nonlinear stochastic optimization with linear constraints. The method of ɛ‐feasible solution by series of Monte‐Carlo estimators has been developed for solving this problem avoiding “jamming” or “zigzagging”. Our approach is distinguished by two peculiarities: the optimality of solution is tested in a statistical manner and the Monte‐Carlo sample size is adjusted so as to decrease the total amount of Monte‐Carlo trials and, at the same time, to guarantee the estimation of the objective function with an admissible accuracy. Under some general conditions we prove by the martingale approach that the proposed method converges a.s. to the stationary point of the problem solved. As a counterexample the maximization of the probability of portfolio desired return is given, too.

31 July 2009 in Methodology and Computing in Applied Probability
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LSLeonidas Sakalauskas
Leonidas Sakalauskas

14 January 2009 in Journal of Optimization Theory and Applications
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USUtena University of Applied Sciences
Utena University of Applied Sciences
LSLeonidas Sakalauskas
Leonidas Sakalauskas