Ibragim R. Atadjanov

Bio: Ibragim R. Atadjanov is an academic researcher from Kyung Hee University. The author has contributed to research in topics: Symmetry (geometry) & Reflection symmetry. The author has an hindex of 2, co-authored 7 publications receiving 47 citations.

Reflection Symmetry Detection via Appearance of Structure Descriptor

Abstract: Symmetry in visual data represents repeated patterns or shapes that is easily found in natural and human-made objects. Symmetry pattern on an object works as a salient visual feature attracting human attention and letting the object to be easily recognized. Most existing symmetry detection methods are based on sparsely detected local features describing the appearance of their neighborhood, which have difficulty in capturing object structure mostly supported by edges and contours. In this work, we propose a new reflection symmetry detection method extracting robust 4-dimensional Appearance of Structure descriptors based on a set of outstanding neighbourhood edge segments in multiple scales. Our experimental evaluations on multiple public symmetry detection datasets show promising reflection symmetry detection results on challenging real world and synthetic images.

Bilateral symmetry detection based on scale invariant structure feature

Abstract: Symmetry is a salient visual pattern in images. Symmetrical structure attracts human eye more than other regions. Therefore, detecting symmetry in an image is one of the crucial tasks in pattern recognition and computer vision research. Sparse key point based symmetry detection methods have been proposed which are fast and robust to noise showing superior detection performance. However, such local appearance-based methods have difficulties in capturing structure based patterns mostly supported by edges and contours. In this paper, we propose a scale invariant structure feature which describes points on extremum curvature along edges. We propose to use a histogram of curvature responses at respective scale space for description. Experimental evaluation on public shape dataset and real world images show that our structure feature works better in detecting visually salient structure based symmetry patterns.

Visually Guided Acquisition of Contact Dynamics and Case Study in Data-Driven Haptic Texture Modeling

Abstract: Data-driven modeling of human hand contact dynamics starts with a tedious process of data collection. The data of contact dynamics consist of an input describing an applied action and response stimuli from the environment. The quality and stability of the model mainly depend on how well data points cover the model space. Thus, in order to build a reliable data-driven model, a user usually collects data dozens of times. In this article, we aim to build an interactive system that assists a user in data collection. We develop an online segmentation framework that partitions a multivariate streaming signal. Real-time segmentation allows for tracking the process of how the model space is being populated. We applied the proposed framework for a haptic texture modeling use-case. In order to guide a user in data collection, we designed a user interface mapping applied input to alternative visual modalities based on the theory of direct perception. A combination of the segmentation framework and user interface implements a human-in-loop system, where the user interface assigns the target combination of input variables and the user tries to acquire them. Experimental results show that the proposed data collection schema considerably increases the approximation quality of the model, whereas the proposed user interface considerably reduces mental workload experienced during data collection.

Realistic haptic rendering of hyper-elastic material via measurement-based FEM model identification and real-time simulation

Abstract: This paper presents a measurement-based FEM (finite element method) modeling and haptic rendering framework for objects with hyper-elastic deformation property. A complete set of methods covering the whole process of the measurement-based modeling/rendering paradigm is newly designed and implemented, with a special emphasis on haptic feedback realism. To this end, we first build a data collection setup that accurately captures shape deformation and response forces during compressive deformation of cylindrical material samples. With this setup, training and testing sets of data are collected from four silicone objects having various material profiles. Then, an objective function incorporating both shape deformation and reactive forces is designed and used to identify material parameters based on training data and the genetic algorithm. For real-time haptic rendering, an optimization-based FEM solver is adopted, ensuring around 500 Hz update rate. The whole procedure is evaluated through numerical and psychophysical experiments. The numerical rendering error is calculated based on the difference between simulated and actually measured deformation forces. The errors are also compared to the human perceptual threshold and found to be perceptually negligible. Overall realism of the feedback from the system is also assessed through the psychophysical experiment. A total of twelve participants rated similarity between real and modeled objects, and the results reveal the rendering quality to be at a reasonable level of realism with positive user feedback.

Measurement-based Hyper-elastic Material Identification and Real-time FEM Simulation for Haptic Rendering

Abstract: In this paper, we propose a measurement-based modeling framework for hyper-elastic material identification and real-time haptic rendering. We build a custom data collection setup that captures shape deformation and response forces during compressive deformation of cylindrical material samples. We collected training and testing sets of data from four silicone objects having various material profiles. We design an objective function for material parameter identification by incorporating both shape deformation and reactive forces and utilize a genetic algorithm. We adopted an optimization-based Finite Element Method (FEM) for object deformation rendering. The numerical error of simulated forces was found to be perceptually negligible.

HybridPose: 6D Object Pose Estimation Under Hybrid Representations

Abstract: We introduce HybridPose, a novel 6D object pose estimation approach. HybridPose utilizes a hybrid intermediate representation to express different geometric information in the input image, including keypoints, edge vectors, and symmetry correspondences. Compared to a unitary representation, our hybrid representation allows pose regression to exploit more and diverse features when one type of predicted representation is inaccurate (e.g., because of occlusion). Different intermediate representations used by HybridPose can all be predicted by the same simple neural network, and outliers in predicted intermediate representations are filtered by a robust regression module. Compared to state-of-the-art pose estimation approaches, HybridPose is comparable in running time and is significantly more accurate. For example, on Occlusion Linemod dataset, our method achieves a prediction speed of 30 fps with a mean ADD(-S) accuracy of 79.2%, representing a 67.4% improvement from the current state-of-the-art approach.

HybridPose: 6D Object Pose Estimation under Hybrid Representations.

Abstract: We introduce HybridPose, a novel 6D object pose estimation approach. HybridPose utilizes a hybrid intermediate representation to express different geometric information in the input image, including keypoints, edge vectors, and symmetry correspondences. Compared to a unitary representation, our hybrid representation allows pose regression to exploit more and diverse features when one type of predicted representation is inaccurate (e.g., because of occlusion). Different intermediate representations used by HybridPose can all be predicted by the same simple neural network, and outliers in predicted intermediate representations are filtered by a robust regression module. Compared to state-of-the-art pose estimation approaches, HybridPose is comparable in running time and accuracy. For example, on Occlusion Linemod dataset, our method achieves a prediction speed of 30 fps with a mean ADD(-S) accuracy of 47.5%, representing a state-of-the-art performance. The implementation of HybridPose is available at this https URL.

2017 ICCV Challenge: Detecting Symmetry in the Wild

Abstract: Motivated by various new applications of computational symmetry in computer vision and in an effort to advance machine perception of symmetry in the wild, we organize the third international symmetry detection challenge at ICCV 2017, after the CVPR 2011/2013 symmetry detection competitions. Our goal is to gauge the progress in computational symmetry with continuous benchmarking of both new algorithms and datasets, as well as more polished validation methodology. Different from previous years, this time we expand our training/testing data sets to include 3D data, and establish the most comprehensive and largest annotated datasets for symmetry detection to date; we also expand the types of symmetries to include densely-distributed and medial-axis-like symmetries; furthermore, we establish a challenge-and-paper dual track mechanism where both algorithms and articles on symmetry-related research are solicited. In this report, we provide a detailed summary of our evaluation methodology for each type of symmetry detection algorithm validated. We demonstrate and analyze quantified detection results in terms of precision-recall curves and F-measures for all algorithms evaluated. We also offer a short survey of the paper-track submissions accepted for our 2017 symmetry challenge.

Reflection Symmetry Detection via Appearance of Structure Descriptor

Abstract: Symmetry in visual data represents repeated patterns or shapes that is easily found in natural and human-made objects. Symmetry pattern on an object works as a salient visual feature attracting human attention and letting the object to be easily recognized. Most existing symmetry detection methods are based on sparsely detected local features describing the appearance of their neighborhood, which have difficulty in capturing object structure mostly supported by edges and contours. In this work, we propose a new reflection symmetry detection method extracting robust 4-dimensional Appearance of Structure descriptors based on a set of outstanding neighbourhood edge segments in multiple scales. Our experimental evaluations on multiple public symmetry detection datasets show promising reflection symmetry detection results on challenging real world and synthetic images.

Detecting Approximate Reflection Symmetry in a Point Set Using Optimization on Manifold

Abstract: We propose an algorithm to detect approximate reflection symmetry present in a set of volumetrically distributed points belonging to $\mathbb {R}^d$ containing a distorted reflection symmetry pattern. We pose the problem of detecting approximate reflection symmetry as the problem of establishing correspondences between the points which are reflections of each other and we determine the reflection symmetry transformation. We formulate an optimization framework in which the problem of establishing the correspondences amounts to solving a linear assignment problem and the problem of determining the reflection symmetry transformation amounts to solving an optimization problem on a smooth Riemannian product manifold. The proposed approach estimates the symmetry from the geometry of the points and is descriptor independent. We evaluate the performance of the proposed approach on the standard benchmark dataset and achieve the state-of-the-art performance. We further show the robustness of our approach by varying the amount of distortion in a perfect reflection symmetry pattern where we perturb each point by a different amount of perturbation. We demonstrate the effectiveness of the method by applying it to the problem of 2-D (two-dimensional) and 3-D reflection symmetry detection along with comparisons.