Wyniki wyszukiwania - Biblioteka Nauki

1

Organizacja danych hipsograficznych na mapach numerycznych dla potrzeb trójwymiarowej wizualizacji obszarów o zasięgu globalnym

100%

Demkowicz J.

|

tom T. 7

489-494

PL

Zasadniczym problemem wizualizacji obszarów o zasięgu globalnym jest duża ilość danych przy zachowywaniu możliwie dużej rozdzielczości, która ostatecznie decyduje o dokładności zobrazowania a tym samym o jego przydatności. Zagadnienie to szerzej znane jest jako skalowanie lub generalizacja. W szczególności problemem jest sam sposób przechowywania danych dla dużych obszarów. W artykule przedstawiono sposób przechowywania danych hipsograficznych z punktu widzenia wizualizacji trójwymiarowej na mapach numerycznych, opierający się min. na szeregach Mortona. Przedstawiono również efekty trójwymiarowej wizualizacji rejonu Pomorza Gdańskiego.

EN

The paper presents a proposition of the hypsographic data organization of large areas, in particular for the whole Earth. The proposed method is the Morton sequence spatial data organization. Some 3D visualizations for the Pomeranian Area, based on such hypsographic data organization are also presented.

2

Submerged objects modeling and storing in a global reference context using multiresolution spline technique

100%

Demkowicz J.

|

tom Vol. 18

47-52

EN

Contemporary sensors i.e. multibeam sonars, 3D shuttle radar topography mission elevation data features high resolution. On the other side bathymetric models of different resolution from different sensors are available as well, starting from very high resolution MBS records as well as low resolution records coming from regular scattered measurement. Approximating and eventually visualizing high volume scattered 3D raster data of different resolution results in some difficulties related to computer processing power. The paper presents some advantages of using multiresolution splines combined with the Hilbert curve approach. The proposed approach consists of two stages: firstly, data of different resolution are interpolated using spline technique and finally the knots and control points are saved using the Hilbert curve. Such an approach especially facilitates high volume spatial data level of details (LoD) visualization technique.

3

3D imaging of seabed from electronic chart bathymetric data

63%

Demkowicz J. , Stepnowski A.

|

tom Vol. 4

37--42

EN

Application of 3D imaging and mapping of seabed is very attractive in many areas including marine cartography, navigation. hydrography, GIS systems etc. There are two competing approaches to constructing 3D images of seabed. The first, off-line method, utilizes the bathymetric information extracted from vectorized digital navigational charts. The second one, on-line technique, employs multibeam sonar seabed echo records processing, The paper describes procedures of bathymetric data analysis for the first method along with newly proposed rendering schemes.

4

Instalacja i wstępna analiza danych batymetrycznych pochodzących z echosondy wielowiązkowej

63%

Demkowicz J. , Bikonis K.

|

tom T. 7

495-502

PL

W akustycznym telemonitoringu środowiska morskiego stosowane są dwa rodzaje sonarów, a mianowicie: sonary boczne i echosondy wielowiązkowe. Oba systemy dostarczają danych zarówno dla batymetrii, jak i dla akustycznego obrazowania dna morskiego. Echosondy wielowiązkowe są zaawansowanymi technologicznie urządzeniami, które dzięki wielokierunkowej obserwacji szerokokątnej dna, przy jednoczesnym utrzymaniu wysokiej rozdzielczości kątowej, pozwalają na doskonałą batymetrię i obrazowanie dna morskiego z odbieranych sygnałów echa. Artykuł prezentuje rezultaty instalacji, uruchomienia i wstępnej analizy danych uzyskanych z rzeczywistych pomiarów batymetrycznych za pomocą wysokorozdzielczej echosondy wielowiązkowej firmy Konsgberg. Zaprezentowano również sposoby prezentacji danych, główne źródła błędów oraz sposoby ich rozpoznawania.

EN

Multibeam sonar is an advanced technology for the seafloor mapping. The paper presents Some technical aspects of multibeam processing technology, sources and types of errors and finaly 3D vizualization of raw data acquired by multibeam echosounder EM 3002.

5

Kalman filtering for 3d real time data visualization of multibeam sonar records

63%

Demkowicz J. , Moszyński M.

|

tom Vol. 6

189--194

EN

For the last decade multibeam sonars have been increasingly used for mapping and visualization of the bottom surfaces to provide the 'physical bases' for environmental studies due to theirs unprecedentedly high resolution mapping ability. However, the raw sonar records are subject to systematic errors, random noise and outliers. In this paper Kalman filtering approach to generating optimal estimates of bottom surface from a noisy raw sonar records is presented. The experiment on the surface indicates that after applying the Kalman filtering technique the outliers of raw records can be efficiently detected and removed. Moreover in the same time, the two-step Kalman filtering method is applied, which aims to filter every multibeam sonar swath and enable 3D seabed visualization in real time. The 3D bottom relief before, and after the filtering method application is also presented.

6

EGNOS-Based GNSS receiver for precise positioning in restricted areas

63%

Demkowicz J. , Bikonis K.

|

tom Vol. 19

65--73

EN

Positioning accuracy is very important in many areas, whereas the typical GPS receiver accuracy is often not sufficient. The European Geostationary Navigation Overlay Service (EGNOS), Europe’s first venture into satellite navigation, improves the open public service offered by the Global Positioning System (GPS). As a satellite navigation augmentation system, EGNOS improves the accuracy of GPS by providing a positioning accuracy to within 3 meters. In this paper we present GNSS receivers based on EGNOS, dedicated for precise positioning in restricted areas of continental shelf performance. The article presents some results regarding position accuracy, obtained for a few receivers in that context.

7

MEMS technology quality requirements as applied to multibeam echosounder

63%

Bikonis K. , Demkowicz J.

|

tom nr 4

59--64

EN

Small, lightweight, power-efficient and low-cost microelectromechanical system (MEMS) inertial sensors and microcontrollers available in the market today help reduce the instability of Multibeam Sonars. Current MEMS inertial measurement units (IMUs) come in many shapes, sizes, and costs — depending on the application and performance required. Although MEMS inertial sensors offer affordable and appropriately scaled units, they are not currently capable of meeting all requirements for accurate and precise attitudes, due to their inherent measurement noise. The article presents the comparison of different MEMS technologies and their parameters regarding to the main application, namely Multibeam Echo Sounders (MBES). The quality of MEMS parameters is crucial for further MBES record-processing. The article presents the results of undertaken researches in that area, and these results are relatively positive for low-cost MEMS. The paper undertakes some vital aspect of using MEMS in the attitude and heading reference system (AHRS) context. The article presents a few aspects of MEMS gyro errors and their estimation process in the context of INS processing flow, as well as points out the main difficulties behind the INS when using a few top MEMS technologies.

8

Design of the dual constellation GPS/GALILEO mobile device for improving navigation of the visually impaired in an urban area

45%

Drypczewski K. , Moszyński M. , Demkowicz J. , Bikonis K. , Stepnowski A.

|

tom nr 4

15--20

EN

The article discusses damages of essential tribological associations in crankshaft and piston systems of large power two-stroke engines used as main engines, which take place during transport tasks performed by those ships. Difficulties are named which make preventing those damages impossible, despite the fact that the technical state of engines of this type is identified with the aid of complex diagnostic systems making use of advanced computer technology. It is demonstrated that one of causes of the damages is the lack of research activities oriented on recognising random properties of the loads leading to those damages. A proposal is made for the loads acting at a given time t on tribological associations in crankshaft and piston systems of internal combustion engines used as main engines to be considered as random variables Qt. At the same time the loads examined within a given time interval tr ≤ t ≤ tz would be considered stochastic processes {Q(t): t ≥ 0}. Essential properties of the loads of the abovementioned tribological associations are named and explained by formulating hypotheses which need empirical verification. Interval estimation is proposed for estimating the expected value E(Qt) of the load Qt acting at time t. A relation is indicated between the mechanical load and the thermal load acting on tribological associations in the ship main engine crankshaft and piston system. A suggestion is formulated that a stochastic form of the relation between these types of load is to be searched for, rather than statistic relation, and a proposal is made to measure the intensity (strength) of the stochastic relation using the Czuprow’s convergence coefficient.