Agnieszka Bier

Error Analysis of Stereo Calibration and Reconstruction

This paper addresses the problem of the propagation of input data errors in the stereovision process and its influence on the quality of reconstructed 3D points. We consider only those particular camera calibration and 3D reconstruction algorithms which employ singular value decomposition (SVD) methods. Using the SVD Jacobian estimation method developed by Papadopoulo and Lourakis, we determine all the partial derivatives of outputs with respect to the inputs and present a set of tests applying them in various stereovision conditions in order to evaluate their impact on the quality of 3D reconstruction.

Pattern Lock Evaluation Framework for Mobile Devices: Human Perception of the Pattern Strength Measure

In this paper we present a multiplatform research framework for acquisition of pattern locks and evaluation of their strength. Along with the design features of the framework itself we provide the analysis of the data set of more than 300 pattern locks acquired by means of this solution. In particular we compare the subjective human rating of pattern memorizability and complexity with the numerical values of pattern strength measure.

Adaptive Math-To-Speech Interface

People with visual impairments suffer because of the lack of well prepared educational resources, especially in the field of mathematics. Existing translation software provides a way to convert basic math documents into Braille language or speak them through Text-To-Speech (TTS) engines, but it requires constant userss interaction and detailed preparations. In this paper we describe a self-contained, adaptive and adaptable Math-To-Speech Interface. We explain the assumptions and design of the system and present exemplary test data. Since the results are quite promising the developed system may be applied in automatic audio presentation tools of mathematical content to sighted as well as visually impaired audience.

Pattern Lock Evaluation Framework for Mobile Devices: Memorizability and Timing Issues

The paper concerns the influence of memory, forgetting and timing issues on the security of mobile applications. The designed framework system was used to further elaboration of the automatic measure, which estimates the quality (strength) of unlock gesture patterns. The data analysis described in detail presents the relations between human subjective ratings of patterns’ complexity and memorizability levels in regards to computed values of quality measure and real-life time spans needed to enter and re-enter the pattern.

Efficiency Comparison of Modern Computer Languages: Sorting Benchmark

The paper surveys the execution features of ready-to-use sorting procedures in various modern computer languages/compilers. The chosen sorting functions were tested for randomly generated data sets of different size and structure resembling the lists or arrays commonly used in real life IT solutions. Our results reveal some differences between particular implementations in efficiency of sorting in terms of CPU load and execution time.

A note on commutators in the group of infinite triangular matrices over a ring

We investigate the commutators of elements of the group of infinite unitriangular matrices over an associative ring with and a commutative group of invertible elements. We prove that every unitriangular matrix of a specified form is a commutator of two other unitriangular matrices. As a direct consequence, we give a complete characterization of the lower central series of the group including the width of its terms with respect to basic commutators and Engel words. With an additional restriction on the ring , we show that the derived subgroup of coincides with the group . These results generalize the results obtained for triangular groups over a field.