Wyniki wyszukiwania - Biblioteka Nauki

1

Space orientation based on image from a mobile camera

100%

Furtak J.

Biuletyn Instytutu Automatyki i Robotyki

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2001

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tom R. 7, nr 15

3-14

EN

This paper presents the pose parameters estimation algorithm for a mobile camera in each of its position. The algorithm is based on recursive filtration of intermediary results. This feature makes a knowledge accumulation during calibration process possible. The algorithm was verified experimentally. The way of an experiment execution method and received results are described.

2

Structured light camera calibration

80%

Garbat P. , Skarbek W. , Tomaszewski M.

Opto-Electronics Review

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2013

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tom Vol. 21, No. 1

23-38

EN

Structured light camera which is being designed with the joined effort of Institute of Radioelectronics and Institute of Optoelectronics (both being large units of the Warsaw University of Technology within the Faculty of Electronics and Information Technology) combines various hardware and software contemporary technologies. In hardware it is integration of a high speed stripe projector and a stripe camera together with a standard high definition video camera. In software it is supported by sophisticated calibration techniques which enable development of advanced application such as real time 3D viewer of moving objects with the free viewpoint or 3D modeller for still objects.

3

Software application for calibration of stereoscopic camera setups

80%

Rzeszotarski D. , Pełczyński P.

Metrology and Measurement Systems

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2012

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tom Vol. 19, nr 4

805-816

EN

The article describes an application for calibration of a stereovision camera setup constructed for the needs of an electronic travel aid for the blind. The application can be used to calibrate any stereovision system consisting of two DirectShow compatible cameras using a reference checkerboard of known dimensions. A method forexperimental verification of the correctness of the calibration is also presented. The developed software is intended for calibration of mobile stereovision systems that focus mainly on obstacle detection.

4

Estimation of pose parameters from a set of least square objective functions

80%

Hati S.

Machine Graphics and Vision

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2008

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tom Vol. 17, No. 3

299-312

EN

In this paper, we have attempted to solve the pose estimation problem for a 3-dimensional object by independently estimating the pose parameters through the minimization of a set of objective, functions, using Gauss approximation techniques for least squares optimization. In our implementation, the 3-D object is assumed to have three degrees of freedom on a flat surface, which is typical of automated visual inspection applications. However, the solution can be also extended to greater degrees of freedom. We have is shown that the pose can be estimated by only considering the x-coordinates of the known vertices in the projected space, but the same is not true if we consider the y-coordinates alone. We propose a set of modified objective functions from which it is possible to find the pose parameters. The parameters have been determined in noisy conditions under 20-dB and 40-dB SNR values and the robustness of the estimators is confirmed.

5

Poprawa kontrastu termicznego na potrzeby kalibracji kamer dla termicznej stereowizji

80%

Moderhak M.

Pomiary Automatyka Kontrola

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2009

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tom R. 55, nr 11

935-937

PL

Praca przybliża sposób na poprawę kontrastu oraz dokładności kalibracji kamer na potrzeby termicznej stereoskopii. Stereoskopia termiczna oraz synteza trójwymiarowych termogramów nadal napotykają problemy techniczne, które w przypadku zwykłej stereoskopii zostały rozwiązane. Jednym z tych problemów jest dokładna kalibracja układu kamer. Omówiono prosty sposób na poprawę kontrastu w trakcie rejestracji sekwencji obrazów wzorca kalibracyjnego. Pozwala to na dokładniejszą kalibrację systemu 3D złożonego z pary kamer termicznych.

EN

This paper describes a method of thermal contrast enhancement in 3D thermal stereo calibration. Thermal stereoscopy still encounters technical problems that have already been solved in visual stereo-scopy. One of them is the accuracy of camera set calibration data which is one of the most important in the whole process of 3D image synthesis. There are many solutions to this problem but none of them is efficient nor easy to perform. Many of them due to the poor thermal image contrast are inaccurate. There is proposed slight modification of RGB camera calibration procedure which allows calibrating IR cameras using common software (CalibrationToolbox for Matlab) and typical calibration patterns (checker board grid) with increased thermal contrast. A short introduction to the stereo calibration procedure is given in the paper. The calibration pattern is described and quantitative and qualitative comparison between the optical and thermal calibration is performed. The method of contrast enhancement and the analysis of thermal calibration results are presented. This method applied to thermal stereo pair calibration seems to provide better calibration accuracy and makes the procedure invulnerable to ambient IR radiation which can cause reflections disturbing the process.

6

Data fusion in web-based visualization of 3D scene semantic model

80%

Jabłoński M.

Image Processing & Communications

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2013

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tom Vol. 18, no. 2-3

61--70

EN

In the paper, the subsystem for graphical visualization of semantic messages has been proposed and configuration dataflow has been described. The key problem in 3D object rendering over video camera image is fusion of parameters collected during camera calibration and pose estimation with models of visualized objects. Pose estimation results and transformation matrix setup were described. Proposed system has been developed in HTML5 internet web page format that uses portable JavaScript language and WebGL library that make use of GPU device. Presented prototype can be used by a web browser on desktop PC as well as on mobile device. No third-party software is necessary.

7

System for 3D localisation of malformations in the human brain

80%

Ostergaard L. R. , Lind J. , Larsen O. V. , Nielsen H. , Bartholdy N. J. , Haase J.

Machine Graphics and Vision

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1998

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tom Vol. 7, No. 1/2

159-167

EN

A 3D localisation system for pre-operating planning is presented. The developed localisation system is able to estimate the 3D position of a target, e.g. an AVM (Arterio-Venous Malformation), based on a set of digital X-ray images. Distortion correction and camera calibrations is performed in order to obtain accurate 3D estimates. The system is tested on a plexiglass phantom with embedded steel pellets offering 126 test points with known 3D positions. The test has shown that the system is able to estimate 3D positions with a mean error of 0.33 mm and a maximum error of 1.18 mm. The required accuracy is 0.16 mm and the test showed that more than 90% of the 3D position estimates fulfilthis requirement.

8

Research on camera calibration using new optimization strategy

80%

Li L.

Opto-Electronics Review

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2011

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tom Vol. 19, No. 4

454-461

EN

An important task for stereo vision is camera calibration, whose goal is to obtain the intrinsic and extrinsic parameters of each camera. This paper proposes a new accurate calibration method with multilevel process of camera parameters. In or- der to improve the calibration accuracy, a sub-pixel corner detection method is presented. We start with several views of a planar calibration to obtain some intrinsic camera parameters and to build an accurate model with lens distortion on a planar calibration target. Flexibly making use of geometry imaging theory, our algorithm obtains all the parameters through logical organization of solving order, accordingly avoids obtaining possible local optimized problem when solving the non-linear equation, gets over the relativity influence of every unknown parameters of traditional calibration way, and makes the error distributed among the constraint relation of parameters. Experiments with real images are carried out to verify the image correction effect and numerical robustness of our results. Compared with classical calibration techniques, that use expensive equipment and complicated mathematical computation, the proposed technique, which was verified by experiment, achieves high accuracy and reliable parameters.

9

Real-time camera pose estimation based on volleyball court view

70%

Szelag K. , Kurowski P. , Bolewicki P. , Sitnik R.

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tom Vol. 27, No. 2

202--212

EN

The use of technology in sports has increased in recent years. One of the most influential of these technologies is referee support systems. Team sports such as volleyball require accurate and robust tracking systems that do not affect either the players or the court. This paper introduces the application of intrinsic and extrinsic camera calibration in a 12-camera volleyball referee system. Intrinsic parameters are calculated by using the classic pinhole model and Zhang’s method. To perform extrinsic calibration in real time, the volleyball court is treated as a global calibration artifact. Calibration keypoints are defined as court-line intersections. In addition, a new keypoint detection algorithm is proposed. It enables achievement of an accurate camera pose in regard to the court. With all 12 cameras calibrated in a common coordinate system, a dynamic camera stereo pair creation is possible. Therefore, with known ball 2D image coordinates, the 3D real ball coordinates can be reconstructed and the ball trajectory can be estimated. The performance of the proposed method is tested on a synthetic data set, including 3Ds Max rendering and real data scenarios. The mean camera pose error calculated for data biased with keypoint detection errors is approximately equal to 0.013% of the measurement volume. For the real data experiment with a human hand phantom, it is possible to determine the presence of the human phantom on the basis of the ball reflection attitude.

10

Homography of central points for optical distortion compensation

70%

Nowakowski A. , Skarbek W.

Opto-Electronics Review

|

2007

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tom Vol. 15, No. 4

202-209

EN

The paper presents a novel radial lens distortion modelling method for vision systems. It is based on single images of chessboard planar pattern, in which calibration points (corners of chessboard squares) are localised. The points, which are situated near the image centre, where the distortion is negligible, are used to determine undistorted grid of calibration points, by parameters of radial model by the linear least square method. Having the distortion model, the dense compensation is performed with support of bilinear interpolation and a sparse compensation by Newton iterative scheme providing subpixel accuracy.

11

Practical camera calibration and image rectification in monocular road traffic applications

60%

Rodríguez T.

|

tom Vol. 15, No. 1

51-71

EN

In this paper we follow apractical approach to the problem of camera calibration and image formation in a typical computer vision based traffic monitoring system. Our study starts by analysing in detail the capturing scenario and the undesirable effects resulting from the application of the pin-hole camera model to traffic images. Based on the acquired experience, we present an integral method to obtain the transformation matrices required to calibrate the camera and to construct in real time a rectified and sub-sampled image where perspective effects on the road plane have been removed. The motivation for this perspective-free image is to reduce the amount of data which must be computed (while avoiding loss of relevant information), remove influences from objects external to the capturing area and simplify the operation of the subsequent detection and tracking stages. The latter statement is justified since vehicle shapes can now be approximated by rectangles, the distance between any two neighbouring points on the road plane remains constant all over the image, and parallel trajectories are restored in the rectified image.

12

Kalibracja systemów stereowizyjnych przy użyciu odpornej metody podwójnej płaszczyzny

60%

Rotter P. , Byrski W. , Dajda M.

|

tom R. 15, nr 12

121-126

PL

W metodzie podwójnej płaszczyzny (ang. double plane) zależność między współrzędnymi obrazowymi a współrzędnymi w przestrzeni trójwymiarowej jest obliczana na podstawie czterech przekształceń płaszczyzny na płaszczyznę (dwie kamery i dwie płaszczyzny kalibracyjne). Metoda jest intuicyjna i łatwa w implementacji, lecz ma poważną wadę w postaci złego uwarunkowania zadania dla pewnych obszarów przestrzeni. W artykule proponujemy odporną metodę kalibracji, która wykorzystuje dodatkowo trzecią płaszczyznę kalibracyjną. Jest to płaszczyzna wirtualna, która nie jest fizycznie elementem wzorca, ale jest zdefiniowana przez odpowiednio rozmieszczone punkty kalibracyjne na dwóch płaszczyznach podstawowych. Proponowany algorytm wykorzystuje liniową kombinację trzech par płaszczyzn: dla par płaszczyzn, które mogą generować błędy numeryczne przypisywana jest niska waga, minimalizująca ich wpływ na wynik końcowy. Eksperymenty wykazały dużą dokładność i wiarygodność proponowanej metody w stosunku do podstawowej wersji algorytmu: błąd średniokwadratowy i błąd maksymalny zostały zredukowane odpowiednio 4- i 20-krotnie.

EN

In double-plane method for stereovision system calibration the correspondence between screen coordinates and location in 3D space is calculated based on four plane-to-plane transformations: there are two planes of the calibration pattern and two cameras. The method is intuitive and easy to implement but the main disadvantage is ill-conditioning for some spatial locations. In this paper we proposed a robust method which exploits the third plane which physically does not belong to the calibration pattern but can be calculated from the set of reference points. Our algorithm uses combination of three calibration planes with weights which depend on screen coordinates of the point of interest: a pair of planes which could cause numerical errors receives small weight and has practically no inl uence on the i nal results. We analysed errors and their distribution in 3D space for basic and improved algorithm. Experiments demonstrate high accuracy and reliability of our method comparing to the basic version: mean square error and maximum error are reduced 4 times and 20 times respectively.

13

Accuracy analysis of automatic distortion correction

60%

Kolecki J. , Rzonca A.

|

nr 1

14

The analysis of the results of aerial photography experiments on the basis of a developed UAV model

60%

Hlotov V. , Siejka Z. , Kolеsnichenko V. , Prokhorchuk O. , Tserklevych A. , Babiy L.

Infrastruktura i Ekologia Terenów Wiejskich

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2015

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nr IV/3

15

Software Application for Calibration of Stereoscopic Camera Setups

60%

Rzeszotarski D. , Pełczyński P.

|

16

Kalibracja kamer z zastosowanym warunkiem Scheimpfluga

51%

Tokarczyk R. , Jędrzejek M.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

|

2010

|

tom Vol. 21

385--394

PL

Zastosowanie warunku Scheimpfluga w kamerach powoduje, że dystorsja obiektywu nie jest symetryczna wokół punktu głównego zdjęcia, a przyjęcie tego punktu jako początku promieni radialnych dla dystorsji powoduje znaczące obniżenie dokładności fotogrametrycznego pomiaru. Dodatkowo, zmienia się charakter dystorsji, jej zniekształcenie nie jest kołowe, a eliptyczne. Dotychczasowe rozwiązania problemu polegają na dodaniu do parametrów kalibracji kamery kąta nachylenia płaszczyzny rejestracji w stosunku do płaszczyzn głównych obiektywu kamery i wyznaczenie ich w procesie wyrównania sieci z samokalibracją. W przypadkach stosowania metod jednoobrazowych, wykorzystywanych na przykład w pomiarach z zastosowaniem profili świetlnych, znajomość parametrów kalibracji można ograniczyć tylko do błędów obrazu – przede wszystkim do wpływu dystorsji obiektywu. W pracy podano proste obliczeniowo metody wyznaczenia błędów obrazu dla zdjęć wykonanych kamerą z warunkiem Scheimpfluga. Pierwszy polega na wyznaczeniu wyinterpolowanych poprawek do pomierzonych współrzędnych w oparciu o „mapę” odchyłek otrzymaną na podstawie przekształcenia rzutowego płaskiego wielopunktowego pola testowego na zdjęcie. Druga metoda wymaga obliczenia oprócz parametrów dystorsji również punktu najlepszej symetrii dystorsji wykorzystując odchyłki po transformacji rzutowej. Badania wykonano w oparciu o dane rzeczywiste, jak i symulacyjne. Rezultaty usunięcia wpływu dystorsji pierwszą z metod okazały się znacznie lepsze od drugiej metody, pozwoliły na zmniejszenie wpływu błędu dystorsji do poziomu błędów przypadkowych pomiaru.

EN

Automatic processes of manufacturing supervision with digital cameras often need to employ the Scheimpflug condition. This is quite common when registering profiles with a laser light. The Scheimplug condition is applied in this case because usually the registration plane cannot be set in parallel to the plane of a laser profile. Moreover, the low-light conditions forcing the use of large diaphragm size and low image acquisition distance imply that the depth of field is insufficient. Setting up three planes: lens main, image and profile in a way that they intersect within one edge, causes that the axis of the lens impales image plane at a point distant from the principal point, which in the analytical evaluation of the photogrammetric networks is adopted as the best-distortionsymmetry point. The Scheimpflug condition causes that the lens distortion (a feature significantly influencing the central projection) is not symmetrical around the principal point and, assuming this point as the origin of radial rays, leads to significant reduction of accuracy of measurement. A solution to this problem is to include the incidence angle between the detector array and lens main planes in the calibration parameters and their evaluation in the self-calibration network adjustment. This best solution from the substantive point of view thus needs elaboration of a specific software for self-calibration bundle adjustment, which is costly and time consuming. In this paper the different – computationally easier methods for the evaluation of image errors for the images taken considering the use of a camera with the Scheimpflug condition. The first method involves determination of interpolated corrections to measured coordinates based on a “deviation map” obtained from the projective transform of a planar, multi-point test-field on the image. The second method employs the evaluation of the best-distortion-symmetry point using the deviations evaluated after the projective transform, approximated by a radial and tangential distortion polynomial evaluated regarding this point. The research was conducted using real as well as simulated data.

17

Calibration low-cost cameras with wide-angle lenses for measurements

51%

Wierzbicki D.

|

2018

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tom Vol. 12, No. 2

45--51

EN

So far too many examinations concerning the possibility of the application action cameras weren’t conducted in UAV photogrammetric studies. However in the recent time development of the action cameras production technology he let receive sensors which are light, userfriendly, and most importantly can gain images and video sequences of high resolution. The essential meaning has taking into account the camera’s influencing factors in UAV photogrammetry. Due to the fact that the action cameras are non-metric cameras the significant influence on the quality of photogrammetric studies has a stability internal orientation of elements of such cameras. Within the framework of carried out research calibration of five GoPro Hero 4 Black. The calibration of cameras was carried out on different calibration tests in the GML Camera Calibration Toolbox and Agisoft Lens software. Different calibration setups and processing are presented and discussed in this article. Additionally a repetitiveness of achieved results of the calibration was examined in five GoPro cameras Hero 4 Black. Dedicated calibration templates in the form of chessboards were used to the calibration. As a part of the research a comparative analysis of the results have been done. Based on performed examinations a repetitiveness of determined internal orientation elements was checked under different video acquisition modes.

18

Accuracy analysis of automatic distortion correction

51%

Kolecki J. , Rzonca A.

Geodesy and Cartography

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2015

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tom Vol. 64, no. 1

3--14

EN

The paper addresses the problem of the automatic distortion removal from images acquired with non-metric SLR camera equipped with prime lenses. From the photogrammetric point of view the following question arises: is the accuracy of distortion control data provided by the manufacturer for a certain lens model (not item) sufficient in order to achieve demanded accuracy? In order to obtain the reliable answer to the aforementioned problem the two kinds of tests were carried out for three lens models. Firstly the multi-variant camera calibration was conducted using the software providing full accuracy analysis. Secondly the accuracy analysis using check points took place. The check points were measured in the images resampled based on estimated distortion model or in distortion-free images simply acquired in the automatic distortion removal mode. The extensive conclusions regarding application of each calibration approach in practice are given. Finally the rules of applying automatic distortion removal in photogrammetric measurements are suggested.

PL

Publikacja ma na celu przedstawienie wyników automatycznego usuwania dystorsji dla niemetrycznej kamery z obiektywem stałoogniskowym. Z punktu widzenia fotogrametrii pojawia się zasadnicze pytanie, czy dokładność określenia dystorsji dla danego typu obiektywu (a nie egzemplarza) jest wystarczająca, żeby otrzymać oczekiwane dokładności pomiaru fotogrametrycznego. W tym celu wykonano dwa rodzaje obliczeń kontrolnych. Pierwsze obliczenia to kalibracja kamery w wariantach zapewniających szeroką dyskusję wyników, wykonana w oprogramowaniu zapewniającym podanie pełnej analizy dokładności. Dodatkowo każdy wariant został sprawdzony poprzez kalibrację kontrolną, którą policzono na podstawie pomiaru zdjęć z fizycznie usuniętym wpływem dystorsji. Drugi etap obliczeń – analiza dokładności – polegał na wykonaniu pomiarów sprawdzających punktów kontrolowanych na zdjęciach dla wszystkich 3 zestawów przyjętych lub obliczonych elementów orientacji wewnętrznej oraz dystorsji usuniętej automatycznie lub programem, na podstawie wyników kalibracji. W publikacji zamieszczono obszerny komentarz dotyczący praktycznych aspektów stosowania każdej z tych metod kalibracji. Wniosek ostateczny podaje zasady stosowania wyników automatycznej redukcji dystorsji w zastosowaniach fotogrametrycznych.

19

Kalibracja wizyjnego systemu pozycjonowania przedmiotu obrabianego na obrabiarce CNC

51%

Domek S. , Pajor M. , Grudziński M. , Okarma K. , Dworak P.

Modelowanie Inżynierskie

|

2013

|

tom T. 15, nr 46

21--27

PL

W pracy przedstawiono dedykowany układ pomiarowy do skanowania geometrii przedmiotu obrabianego na obrabiarce CNC, wymagający jednak precyzyjnego zorientowania skanera 3D względem maszynowego układu odniesienia obrabiarki CNC. Przedstawiono techniki kalibracji z użyciem wielobarwnych tablic kalibracyjnych i świateł strukturalnych, jak też stosowane w kalibracji i skanowaniu metody geometryczne oraz techniki tworzenia obrazów do kalibracji z tzw. kamery wirtualnej. Ponadto przedstawiono wpływ nieliniowej charakterystyki wyświetlania projektora i sposoby jej kompensacji.

EN

In the paper a dedicated measurement system for the 3D geometry scanning of the workpieces on the CNC machine tools is presented, which requires a precise knowledge about its relative position and orientation according to the reference coordinate system of the CNC machine tool. We present the calibration methods based on the colour calibration patterns and structural light as well as some geometrical methods usedfor the calibration and scanning. Moreover, some methods applied for the synthesis of images from virtual cameras are discussed as well as the influence of the nonlinear characteristics of the light projectors and methods of its compensation.

20

Wykorzystanie aparatu cyfrowego telefonu komórkowego do wizualizacji 3D kapliczki

51%

Tokarczyk R. , Kolecki J. , Tokarczyk P.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

|

2007

|

tom Vol. 17b

769--779

PL

W opracowaniu przedstawiono prace zmierzające do wizualizacji 3D zabytkowej kapliczki krakowskiej z zastosowaniem kamery cyfrowej aparatu komórkowego Nokia 6280 wyposażonej w obiektyw o stałym ogniskowaniu i dwumegapikselowa matryce CMOS. Poprzedzone one zostały badaniem fotogrametrycznej przydatności tej kamery na polu testowym AGH do kalibracji kamer bliskiego zasięgu. Porównano je z wynikami badania dwu innych aparatów cyfrowych: kompaktowego o stałym ogniskowaniu Olympus Camedia C120 oraz lustrzanki Minolta Dynax ze stałoogniskowym obiektywem 20 mm. Mimo słabo modelowanej dystorsji obiektywu aparatu komórkowego Nokia 6280 uzyskano w wyniku fotogrametrycznego wcięcia w przód dokładność względna pomiaru położenia punktu około 1/1230, co pozwala na wykorzystanie tej kamerki do wielu zagadnień pomiarowych. Jako przykład takiego zastosowania wykonano trójwymiarowa wizualizacje zabytkowej kapliczki, przy minimum prac terenowych. Modele na podstawie wykonanych stereogramów zbudowano i zwektoryzowano za pomocą autografu VSD, wykorzystując do orientacji bezwzględnej modeli wersje orientacji bezwzględnej etapami. Dalsze opracowanie wykonano z użyciem programu AutoCAD. Model krawędziowy obiektu został pokryty teksturami ze zdjęć i teksturami autorskimi. Kontrola utworzonego modelu kapliczki oparta na porównaniu długości odcinków pomierzonych na nim i pomiarem bezpośrednim wykazała, że dokładność pomiaru fotogrametrycznego jest wystarczająca dla dokładności wymaganej dla tego rodzaju obiektu.

EN

This paper describes all work leading to 3D visualisation of shrine in Krakow with the use of digital camera equipped in fixed-focus lens and 2 Mpix CMOS sensor built in Nokia 6280 mobile phone. They were preceded by the study of photogrammetric suitability of the camera on special test field used for close-range cameras, and the results were compared with two other digital cameras: compact free focus Olympus Camedia C120 digital camera and Minolta Dynax 5D digital SLR camera equipped with 20 mm lens. Despite poor modelling of lens distortion in Nokia 6280 digital camera, an absolute accuracy of 1/1230 was achieved using photogrammetric intersection. This result enables the use of this camera as a tool for various measurement issues. A 3D visualization of shrine with as few as possible field works was an example of such issue. Based on images, photogrammetric models were built and vectorised using VSD software and stage-absolute orientation of photogrammetric models. Further development was carried out using AutoCAD software. A wireframe model was covered with photo-realistic and user-defined textures. Control of constructed model was based on a comparison of segments measured in the field and on the model. It showed that accuracy of photogrammetric measurement is sufficient for this type of object.