Search Results for author: Petros Maragos

Found 60 papers, 26 papers with code

Greek Sign Language Recognition for the SL-ReDu Learning Platform

no code implementations SLTAT (LREC) 2022 Katerina Papadimitriou, Gerasimos Potamianos, Galini Sapountzaki, Theodore Goulas, Eleni Efthimiou, Stavroula-Evita Fotinea, Petros Maragos

There has been increasing interest lately in developing education tools for sign language (SL) learning that enable self-assessment and objective evaluation of learners’ SL productions, assisting both students and their instructors.

Sign Language Recognition

Multiclass Neural Network Minimization via Tropical Newton Polytope Approximation

1 code implementation ICML 2020 Georgios Smyrnis, Petros Maragos

The field of tropical algebra is closely linked with the domain of neural networks with piecewise linear activations, since their output can be described via tropical polynomials in the max-plus semiring.

Mushroom Segmentation and 3D Pose Estimation from Point Clouds using Fully Convolutional Geometric Features and Implicit Pose Encoding

1 code implementation17 Apr 2024 George Retsinas, Niki Efthymiou, Petros Maragos

We have validated the effectiveness of the proposed implicit-based approach for a synthetic test set, as well as provided qualitative results for a small set of real acquired point clouds with depth sensors.

3D Pose Estimation Instance Segmentation +1

3D Facial Expressions through Analysis-by-Neural-Synthesis

no code implementations5 Apr 2024 George Retsinas, Panagiotis P. Filntisis, Radek Danecek, Victoria F. Abrevaya, Anastasios Roussos, Timo Bolkart, Petros Maragos

Instead, SMIRK replaces the differentiable rendering with a neural rendering module that, given the rendered predicted mesh geometry, and sparsely sampled pixels of the input image, generates a face image.

3D Face Reconstruction Neural Rendering

Neural Text to Articulate Talk: Deep Text to Audiovisual Speech Synthesis achieving both Auditory and Photo-realism

1 code implementation11 Dec 2023 Georgios Milis, Panagiotis P. Filntisis, Anastasios Roussos, Petros Maragos

Our method, which we call NEUral Text to ARticulate Talk (NEUTART), is a talking face generator that uses a joint audiovisual feature space, as well as speech-informed 3D facial reconstructions and a lip-reading loss for visual supervision.

Lip Reading Speech Synthesis +1

Pre-training Music Classification Models via Music Source Separation

2 code implementations24 Oct 2023 Christos Garoufis, Athanasia Zlatintsi, Petros Maragos

In this paper, we study whether music source separation can be used as a pre-training strategy for music representation learning, targeted at music classification tasks.

Classification Genre classification +5

Feather: An Elegant Solution to Effective DNN Sparsification

1 code implementation3 Oct 2023 Athanasios Glentis Georgoulakis, George Retsinas, Petros Maragos

Neural Network pruning is an increasingly popular way for producing compact and efficient models, suitable for resource-limited environments, while preserving high performance.

Network Pruning

Matrix Factorization in Tropical and Mixed Tropical-Linear Algebras

no code implementations25 Sep 2023 Ioannis Kordonis, Emmanouil Theodosis, George Retsinas, Petros Maragos

Matrix Factorization (MF) has found numerous applications in Machine Learning and Data Mining, including collaborative filtering recommendation systems, dimensionality reduction, data visualization, and community detection.

Collaborative Filtering Community Detection +3

Photorealistic and Identity-Preserving Image-Based Emotion Manipulation with Latent Diffusion Models

1 code implementation6 Aug 2023 Ioannis Pikoulis, Panagiotis P. Filntisis, Petros Maragos

In this paper, we investigate the emotion manipulation capabilities of diffusion models with "in-the-wild" images, a rather unexplored application area relative to the vast and rapidly growing literature for image-to-image translation tasks.

Image-to-Image Translation Translation

Revisiting Tropical Polynomial Division: Theory, Algorithms and Application to Neural Networks

no code implementations27 Jun 2023 Ioannis Kordonis, Petros Maragos

Furthermore, we develop a relationship of tropical polynomial division with the computation of the convex hull of unions of convex polyhedra and use it to derive an exact algorithm for tropical polynomial division.

ViDaS Video Depth-aware Saliency Network

no code implementations19 May 2023 Ioanna Diamanti, Antigoni Tsiami, Petros Koutras, Petros Maragos

We introduce ViDaS, a two-stream, fully convolutional Video, Depth-Aware Saliency network to address the problem of attention modeling ``in-the-wild", via saliency prediction in videos.

object-detection Object Detection +2

OVeNet: Offset Vector Network for Semantic Segmentation

1 code implementation25 Mar 2023 Stamatis Alexandropoulos, Christos Sakaridis, Petros Maragos

Motivated by this prior, we design a novel two-head network, named Offset Vector Network (OVeNet), which generates both standard semantic predictions and a dense 2D offset vector field indicating the offset from each pixel to the respective seed pixel, which is used to compute an alternative, seed-based semantic prediction.

Optical Character Recognition (OCR) Scene Understanding +1

Medical Face Masks and Emotion Recognition from the Body: Insights from a Deep Learning Perspective

1 code implementation20 Feb 2023 Nikolaos Kegkeroglou, Panagiotis P. Filntisis, Petros Maragos

In this paper, we conduct insightful studies about the effect of face occlusion on emotion recognition performance, and showcase the superiority of full body input over the plain masked face.

Emotion Recognition

Multi-Source Contrastive Learning from Musical Audio

1 code implementation14 Feb 2023 Christos Garoufis, Athanasia Zlatintsi, Petros Maragos

Contrastive learning constitutes an emerging branch of self-supervised learning that leverages large amounts of unlabeled data, by learning a latent space, where pairs of different views of the same sample are associated.

CoLA Contrastive Learning +6

VP-SLAM: A Monocular Real-time Visual SLAM with Points, Lines and Vanishing Points

no code implementations23 Oct 2022 Andreas Georgis, Panagiotis Mermigkas, Petros Maragos

Traditional monocular Visual Simultaneous Localization and Mapping (vSLAM) systems can be divided into three categories: those that use features, those that rely on the image itself, and hybrid models.

Simultaneous Localization and Mapping Translation

3D Neural Sculpting (3DNS): Editing Neural Signed Distance Functions

1 code implementation28 Sep 2022 Petros Tzathas, Petros Maragos, Anastasios Roussos

In recent years, implicit surface representations through neural networks that encode the signed distance have gained popularity and have achieved state-of-the-art results in various tasks (e. g. shape representation, shape reconstruction, and learning shape priors).

Neural Sign Reenactor: Deep Photorealistic Sign Language Retargeting

no code implementations3 Sep 2022 Christina O. Tze, Panagiotis P. Filntisis, Athanasia-Lida Dimou, Anastasios Roussos, Petros Maragos

In this paper, we introduce a neural rendering pipeline for transferring the facial expressions, head pose, and body movements of one person in a source video to another in a target video.

Neural Rendering Sign Language Production

Visual Speech-Aware Perceptual 3D Facial Expression Reconstruction from Videos

1 code implementation22 Jul 2022 Panagiotis P. Filntisis, George Retsinas, Foivos Paraperas-Papantoniou, Athanasios Katsamanis, Anastasios Roussos, Petros Maragos

The recent state of the art on monocular 3D face reconstruction from image data has made some impressive advancements, thanks to the advent of Deep Learning.

3D Face Reconstruction 3D Reconstruction

Trainable Learning Rate

no code implementations29 Sep 2021 George Retsinas, Giorgos Sfikas, Panagiotis Filntisis, Petros Maragos

Selecting an appropriate learning rate for efficiently training deep neural networks is a difficult process that can be affected by numerous parameters, such as the dataset, the model architecture or even the batch size.

An audiovisual and contextual approach for categorical and continuous emotion recognition in-the-wild

1 code implementation7 Jul 2021 Panagiotis Antoniadis, Ioannis Pikoulis, Panagiotis P. Filntisis, Petros Maragos

In this work we tackle the task of video-based audio-visual emotion recognition, within the premises of the 2nd Workshop and Competition on Affective Behavior Analysis in-the-wild (ABAW2).

Emotion Recognition

Exploring Temporal Context and Human Movement Dynamics for Online Action Detection in Videos

no code implementations26 Jun 2021 Vasiliki I. Vasileiou, Nikolaos Kardaris, Petros Maragos

Nowadays, the interaction between humans and robots is constantly expanding, requiring more and more human motion recognition applications to operate in real time.

Online Action Detection Temporal Action Localization

Exploiting Emotional Dependencies with Graph Convolutional Networks for Facial Expression Recognition

1 code implementation7 Jun 2021 Panagiotis Antoniadis, Panagiotis P. Filntisis, Petros Maragos

To evaluate the performance of our method under real-world conditions we perform extensive experiments on the AffectNet and Aff-Wild2 datasets.

Ranked #8 on Facial Expression Recognition (FER) on AffectNet (Accuracy (7 emotion) metric)

Facial Expression Recognition Facial Expression Recognition (FER)

HTMD-Net: A Hybrid Masking-Denoising Approach to Time-Domain Monaural Singing Voice Separation

no code implementations7 Mar 2021 Christos Garoufis, Athanasia Zlatintsi, Petros Maragos

The advent of deep learning has led to the prevalence of deep neural network architectures for monaural music source separation, with end-to-end approaches that operate directly on the waveform level increasingly receiving research attention.

Computational Efficiency Denoising +1

Grounding Consistency: Distilling Spatial Common Sense for Precise Visual Relationship Detection

1 code implementation ICCV 2021 Markos Diomataris, Nikolaos Gkanatsios, Vassilis Pitsikalis, Petros Maragos

Scene Graph Generators (SGGs) are models that, given an image, build a directed graph where each edge represents a predicted subject predicate object triplet.

Common Sense Reasoning Graph Generation +3

Enhancing Handwritten Text Recognition with N-gram sequence decomposition and Multitask Learning

no code implementations28 Dec 2020 Vasiliki Tassopoulou, George Retsinas, Petros Maragos

In our work, we utilize a Multi-task Learning scheme, training the model to perform decompositions of the target sequence with target units of different granularity, from fine to coarse.

Handwritten Text Recognition Language Modelling +1

Independent Sign Language Recognition with 3D Body, Hands, and Face Reconstruction

no code implementations24 Nov 2020 Agelos Kratimenos, Georgios Pavlakos, Petros Maragos

Independent Sign Language Recognition is a complex visual recognition problem that combines several challenging tasks of Computer Vision due to the necessity to exploit and fuse information from hand gestures, body features and facial expressions.

3D Action Recognition 3D Reconstruction +3

Advances in the training, pruning and enforcement of shape constraints of Morphological Neural Networks using Tropical Algebra

no code implementations15 Nov 2020 Nikolaos Dimitriadis, Petros Maragos

In this paper we study an emerging class of neural networks based on the morphological operators of dilation and erosion.

Sparse Approximate Solutions to Max-Plus Equations with Application to Multivariate Convex Regression

no code implementations6 Nov 2020 Nikos Tsilivis, Anastasios Tsiamis, Petros Maragos

In this work, we study the problem of finding approximate, with minimum support set, solutions to matrix max-plus equations, which we call sparse approximate solutions.

regression

Multiscale Fractal Analysis on EEG Signals for Music-Induced Emotion Recognition

no code implementations30 Oct 2020 Kleanthis Avramidis, Athanasia Zlatintsi, Christos Garoufis, Petros Maragos

Emotion Recognition from EEG signals has long been researched as it can assist numerous medical and rehabilitative applications.

EEG Emotion Classification +1

ChildBot: Multi-Robot Perception and Interaction with Children

no code implementations28 Aug 2020 Niki Efthymiou, Panagiotis P. Filntisis, Petros Koutras, Antigoni Tsiami, Jack Hadfield, Gerasimos Potamianos, Petros Maragos

In this paper we present an integrated robotic system capable of participating in and performing a wide range of educational and entertainment tasks, in collaboration with one or more children.

WSRNet: Joint Spotting and Recognition of Handwritten Words

no code implementations17 Aug 2020 George Retsinas, Giorgos Sfikas, Petros Maragos

The related joint loss leads to a boost in recognition performance, while the Seq2Seq branch is used to create efficient word representations.

Binarization Keyword Spotting

Orientation Attentive Robotic Grasp Synthesis with Augmented Grasp Map Representation

1 code implementation9 Jun 2020 Georgia Chalvatzaki, Nikolaos Gkanatsios, Petros Maragos, Jan Peters

Inherent morphological characteristics in objects may offer a wide range of plausible grasping orientations that obfuscates the visual learning of robotic grasping.

Grasp Generation Robotic Grasping

Weight Pruning via Adaptive Sparsity Loss

1 code implementation4 Jun 2020 George Retsinas, Athena Elafrou, Georgios Goumas, Petros Maragos

Pruning neural networks has regained interest in recent years as a means to compress state-of-the-art deep neural networks and enable their deployment on resource-constrained devices.

Image Classification Network Pruning

How to track your dragon: A Multi-Attentional Framework for real-time RGB-D 6-DOF Object Pose Tracking

1 code implementation21 Apr 2020 Isidoros Marougkas, Petros Koutras, Nikos Kardaris, Georgios Retsinas, Georgia Chalvatzaki, Petros Maragos

We present a novel multi-attentional convolutional architecture to tackle the problem of real-time RGB-D 6D object pose tracking of single, known objects.

Data Augmentation Object Tracking +3

STAViS: Spatio-Temporal AudioVisual Saliency Network

1 code implementation CVPR 2020 Antigoni Tsiami, Petros Koutras, Petros Maragos

We introduce STAViS, a spatio-temporal audiovisual saliency network that combines spatio-temporal visual and auditory information in order to efficiently address the problem of saliency estimation in videos.

Saliency Prediction

Tropical Geometry and Piecewise-Linear Approximation of Curves and Surfaces on Weighted Lattices

no code implementations9 Dec 2019 Petros Maragos, Emmanouil Theodosis

Tropical Geometry and Mathematical Morphology share the same max-plus and min-plus semiring arithmetic and matrix algebra.

regression

Tropical Polynomial Division and Neural Networks

no code implementations29 Nov 2019 Georgios Smyrnis, Petros Maragos

In this work, we examine the process of Tropical Polynomial Division, a geometric method which seeks to emulate the division of regular polynomials, when applied to those of the max-plus semiring.

Binary Classification

RecNets: Channel-wise Recurrent Convolutional Neural Networks

no code implementations28 May 2019 George Retsinas, Athena Elafrou, Georgios Goumas, Petros Maragos

In this paper, we introduce Channel-wise recurrent convolutional neural networks (RecNets), a family of novel, compact neural network architectures for computer vision tasks inspired by recurrent neural networks (RNNs).

General Classification Image Classification

Deeply Supervised Multimodal Attentional Translation Embeddings for Visual Relationship Detection

1 code implementation15 Feb 2019 Nikolaos Gkanatsios, Vassilis Pitsikalis, Petros Koutras, Athanasia Zlatintsi, Petros Maragos

Detecting visual relationships, i. e. <Subject, Predicate, Object> triplets, is a challenging Scene Understanding task approached in the past via linguistic priors or spatial information in a single feature branch.

Relationship Detection Translation +1

Fusing Body Posture with Facial Expressions for Joint Recognition of Affect in Child-Robot Interaction

1 code implementation7 Jan 2019 Panagiotis P. Filntisis, Niki Efthymiou, Petros Koutras, Gerasimos Potamianos, Petros Maragos

In this paper we address the problem of multi-cue affect recognition in challenging scenarios such as child-robot interaction.

Detecting Adversarial Examples in Convolutional Neural Networks

no code implementations8 Dec 2018 Stefanos Pertigkiozoglou, Petros Maragos

This paper focuses on the detection of adversarial examples, which are created for convolutional neural networks that perform image classification.

Image Classification

SUSiNet: See, Understand and Summarize it

no code implementations3 Dec 2018 Petros Koutras, Petros Maragos

In this work we propose a multi-task spatio-temporal network, called SUSiNet, that can jointly tackle the spatio-temporal problems of saliency estimation, action recognition and video summarization.

Ranked #66 on Action Recognition on HMDB-51 (using extra training data)

Action Recognition Saliency Prediction +2

LSTM-based Network for Human Gait Stability Prediction in an Intelligent Robotic Rollator

no code implementations1 Dec 2018 Georgia Chalvatzaki, Petros Koutras, Jack Hadfield, Xanthi S. Papageorgiou, Costas S. Tzafestas, Petros Maragos

In this work, we present a novel framework for on-line human gait stability prediction of the elderly users of an intelligent robotic rollator using Long Short Term Memory (LSTM) networks, fusing multimodal RGB-D and Laser Range Finder (LRF) data from non-wearable sensors.

Pose Estimation

Tropical Modeling of Weighted Transducer Algorithms on Graphs

no code implementations1 Nov 2018 Emmanouil Theodosis, Petros Maragos

Weighted Finite State Transducers (WFSTs) are versatile data structures that can model a great number of problems, ranging from Automatic Speech Recognition to DNA sequencing.

Automatic Speech Recognition Automatic Speech Recognition (ASR) +1

An Adaptive Pruning Algorithm for Spoofing Localisation Based on Tropical Geometry

no code implementations1 Nov 2018 Emmanouil Theodosis, Petros Maragos

In particular, the proposed algorithm tries to localise the attacker by adapting the leniency parameter based on estimates about the state of the solution space.

A Tropical Approach to Neural Networks with Piecewise Linear Activations

no code implementations22 May 2018 Vasileios Charisopoulos, Petros Maragos

We present a new, unifying approach following some recent developments on the complexity of neural networks with piecewise linear activations.

Multimodal Visual Concept Learning with Weakly Supervised Techniques

1 code implementation CVPR 2018 Giorgos Bouritsas, Petros Koutras, Athanasia Zlatintsi, Petros Maragos

Despite the availability of a huge amount of video data accompanied by descriptive texts, it is not always easy to exploit the information contained in natural language in order to automatically recognize video concepts.

Action Recognition Descriptive +4

Theoretical Analysis of Active Contours on Graphs

no code implementations24 Oct 2016 Christos Sakaridis, Kimon Drakopoulos, Petros Maragos

Active contour models based on partial differential equations have proved successful in image segmentation, yet the study of their geometric formulation on arbitrary geometric graphs is still at an early stage.

Image Segmentation Semantic Segmentation

The DIRHA simulated corpus

no code implementations LREC 2014 Luca Cristoforetti, Mirco Ravanelli, Maurizio Omologo, Aless Sosi, ro, Alberto Abad, Martin Hagmueller, Petros Maragos

This paper describes a multi-microphone multi-language acoustic corpus being developed under the EC project Distant-speech Interaction for Robust Home Applications (DIRHA).

Dialogue Management Distant Speech Recognition +2

Spectrum of Fractal Interpolation Functions

no code implementations29 Jun 2009 Nikolaos Vasiloglou, Petros Maragos

In this paper we compute the Fourier spectrum of the Fractal Interpolation Functions FIFs as introduced by Michael Barnsley.

Information Theory Information Theory

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