Michal Krumnikl

Calibration of Short Range 2D Laser Range Finder for 3D SLAM Usage

The laser range finder is one of the most essential sensors in the field of robotics. The laser range finder provides an accurate range measurement with high angular resolution. However, the short range scanners require an additional calibration to achieve the abovementioned accuracy. The calibration procedure described in this work provides an estimation of the internal parameters of the laser range finder without requiring any special three-dimensional targets. This work presents the use of a short range URG-04LX scanner for mapping purposes and describes its calibration. The precision of the calibration was checked in an environment with known ground truth values and the results were statistically evaluated. The benefits of the calibration are also demonstrated in the practical applications involving the segmentation of the environment. The proposed calibration method is complex and detects all major manufacturing inaccuracies. The procedure is suitable for easy integration into the current manufacturing process.

Active Contours without Edges and with Simple Shape Priors

In this paper, we introduce two simple shape priors into the Chan and Vese level-set method, namely, a prescribed area and a prescribed area-to-perimeter ratio of particular objects. It is remarkable that these priors may be easily incorporated into the Euler-Lagrange equation of the original method. As a side effect of our experimenting with the method, we also introduce a new probability-based level-set function, which removes the need for reinitialisation and usually, according to our experience, speeds up the computation. Finally, we also propose a method how to treat, in a simple way, the situation in which the particular objects differ in brightness. Although the mentioned changes make the segmentation more reliable, they almost do not complicate the computation. The results of experiments are also presented.

Three-Dimensional Reconstruction of Macroscopic Features in Biological Materials

This paper covers the topic of three dimensional reconstruction of small textureless formations usually found in biological samples. Generally used reconstructing algorithms do not provide sufficient accuracy for surface analysis. In order to achieve better results, combined strategy was developed, linking stereo matching algorithms with monocular depth cues such as depth from focus and depth from illumination.

The Radio Direction Finding with Advantage of the Software Defined Radio

The radio-frequency engineering recently has gone through extensive development. Software-Defined Radio (SDR) plays an important role in this development, bringing new possibilities to radio-frequency engineering and enables us to look at existing radio technologies in a new, innovative way. One such technology is a Doppler antenna, which allows us to find the direction from which the radio signal of given frequency is being transmitted. The SDR allows us to design and construct a highly-simplified system based on the Doppler antenna array. This paper deals with the design and implementation of such system used for the localization using the Doppler effect and the tests of the designed Doppler antenna system.

EM410x RFID cloned card detection system

RFID tags are nowadays used for granting access to buildings, tracking goods, persons and animals, in electronic toll collection systems, mobile payments, and other application areas. The purpose of this paper is to propose a solution that is capable of detecting fake (cloned) low cost 125 kHz RFID tags. The paper is focusing on detecting clones and emulators of EM410x tags. The proposed method is based on modifying the RFID reader and exploiting the specific features and properties of the fake tags. The experiments performed with the RFID reader with the implementation of the proposed clone detection techniques have shown that it is possible to reliably detect the majority of the publicly available fake tags and emulators. Moreover, the reader is capable of deactivating some of the clone tags if necessary.

On the Usability of Vehicle-to-Roadside Communications Using IEEE 802.11b/g Unplanned Wireless Networks

Wireless networks are achieving a widespread penetration thanks to a variety of low cost solutions; cities are overcrowded with IEEE 802.11 access points. While connecting a notebook to a wireless network is simple, a vehicle connection to a roadside unit is still one of the most challenging topic.

Image segmentation based on electrical proximity in a resistor-capacitor network

Measuring the distances is an important problem in many image-segmentation algorithms. The distance should tell whether two image points belong to a single or, respectively, to two different image segments. The paper deals with the problem of measuring the distance along the manifold that is defined by image. We start from the discussion of difficulties that arise if the geodesic distance, diffusion distance, and some other known metrics are used. Coming from the diffusion equation and inspired by the diffusion distance, we propose to measure the proximity of points as an amount of substance that is transferred in diffusion process. The analogy between the images and electrical circuits is used in the paper, i.e., we measure the proximity as an amount of electrical charge that is transported, during a certain time interval, between two nodes of a resistor-capacitor network. We show how the quantity we introduce can be used in the algorithms for supervised (seeded) and unsupervised image segmentation. We also show that the distance between the areas consisting of more than one point (pixel) can also be easily introduced in a meaningful way. Experimental results are also presented.

A New Method for Bryophyte Canopy Analysis Based on 3D Surface Reconstruction

Recent studies concerning bryophyte canopy structure applied various modern, computer analysis methods for determining moss layer characteristics drawing on the outcomes of a previous research on surface of soil. Surface roughness index Lr was hereby used as a monitor of quality (and condition) of bryophyte canopy. We explored stereo photogrammetry, a non-contact passive method of collecting distance information about surfaces, as a method to acquire 3D model of bryophyte layer and thus Lr and compared it with methods already performed by other authors - contact probe, LED scanning and 3D laser scanning. In contrast to active methods, this method relies on detecting reflected ambient light, therefore, it does not emit any kind of radiation, which can lead to interference with moss photosynthetic pigments, nor does it affect the structure of its layer. This makes it much more suitable for usage in natural environment.

SciJava Interface for Parallel Execution in the ImageJ Ecosystem

ImageJ has become a popular software platform for image processing and its community has developed and made available numerous plugins for scientific audiences. Nevertheless, no platform-wide solution for parallel processing of big data has been created so far. As ImageJ is a part of the SciJava collaboration project, we propose the concept of seamlessly integrating parallelization-providing capability into one of the SciJava libraries. Specifically, this approach strives to make high-performance infrastructure accessible to ImageJ plugin developers whilst remaining extensible and technology-agnostic. Two parallelization approaches were created and experimentally evaluated on an HPC infrastructure. The results indicate good scalability and are promising for prospective integration of the created functionality into the SciJava Common library.

Developing Countermeasures against Cloning of Identity Tokens in Legacy Systems

During the development of a new access system based on modern RFID technologies it was found that companies producing access control systems for residential and office buildings still prefer the use of existing cheap solutions instead of incorporating new technologies. This is mainly due to the additional costs new systems require.