- Tytuł:
-
Fotogrametryczny pomiar elementów walcowanych
Photogrammetric measurement of rolled elements - Autorzy:
-
Tokarczyk, R.
Skoczek, K. - Powiązania:
- https://bibliotekanauki.pl/articles/129850.pdf
- Data publikacji:
- 2008
- Wydawca:
- Stowarzyszenie Geodetów Polskich
- Tematy:
-
fotogrametria bliskiego zasięgu
cyfrowy aparat fotograficzny
przetwarzanie obrazów
pomiar automatyczny
obraz cyfrowy
close-range photogrammetry
digital camera
digital image processing
automatic measurement - Opis:
-
Opracowanie fotogrametrycznej metody pomiaru służącego wyznaczeniu
przemieszczeń i odkształceń elementów walcowanych przeprowadzono w ramach
międzynarodowego projektu prowadzonego przez Katedrę Przeróbki Plastycznej i Metaloznawstwa
Metali Nieżelaznych AGH pt.: ,,Badanie płynięcia materiału w procesie walcowania
pielgrzymowego na zimno”. Badania nowego procesu walcowania pielgrzymowego prowadzone
są na modelu fizycznym walcarki pielgrzymowej. Doświadczenia wykonywane są na materiałach
niemetalicznych (plastelina, woski), i metalicznych (ołów, aluminium). Celem pracy jest
opracowanie metody pomiaru służącego wyznaczeniu odkształcenia materiału walcowanego z plasteliny,
mającego przed walcowaniem kształt wydrążonego walca, a w trakcie walcowania - stożka
ściętego. Jako metodę pomiaru zaproponowano wcięcie w przód z dwu zdjęć zbieżnych o znanej
orientacji wewnętrznej i zewnętrznej, po procesie orientacji wzajemnej i bezwzględnej.
Do rejestracji obrazów wykorzystano skalibrowaną cyfrową lustrzankę Nikon D80, z matrycą 10
megapikseli oraz stałoogniskowym obiektywem Sigma EX DG 20/1,8. Wykonano próbę
automatyzacji pomiaru sygnałów na elemencie walcowanym z użyciem narzędzi programu
Matlab. Przetestowano dwie metody pomiaru: filtracji regionów do detekcji markerów
i wagowanego środka ciężkości do pomiaru ich centrów oraz alternatywnie metodę
wieloetapowego ścieniania na zbinaryzowanym obrazie.
Developing a photogrammetrical method of measuring displacements and deformations of rolled objects was supported by the international project “Investigations of displacements and deformation during cold rolling of tubes in pilgering process” led by the Department of Metal Forming, Cracow University of Technology. Cold rolling of tubes in the pilgering process is one of the most advanced technologies of manufacturing copper pipes used in of water supply systems, heating systems, medical systems, etc. The method makes it is possible to increase the overall deformation by up to 95%. Research on effects of the new process on the size of deformation and behaviour of the rolled material is thus required. The study on the new pilgering process were carried out on a physical model of a pilger mill. The first tests were conducted on non-metallic materials (plasticine, wax), the metallic materials (lead, aluminum) being tested at the last stage of trials. The aim of the proposed measurement method was to determine the deformation of a rolled wax material. Before it was rolled, the object was shaped like a hollow cylinder, a bevelled cone being produced after rolling. Direct intersection of two convergent images, with known interior and exterior orientation, was proposed as the measurement method. For image acquisition, we used 10 Mpx. Nikon D80 digital SLR camera with Sigma EX DG 20/1.8 fixed focus lens. The photogrammetric model is based on the relative orientation of the two images. It is then transformed to the reference system defined by the ground control points using an absolute orientation. After such procedures, image orientation elements are determined. Thus, we are able to calculate 3D coordinates of arbitrary point visible on the two images. The images were acquired from a tripod constructed especially for the needs of the project. The tripod allows moving the camera along the mill. Because the object being deformed is photographed only from the top, to assess deformations on its entire surface the object has to be rotated around its main axis. The photogrammetrical models that are thus created have to be connected into a special reference system. The first results of photogrammetric measurements were obtained by using the VSD AGH digital stereo plotter. It allowed us to check the correctness of the method and to create the first deformation plots. Subsequently, the image measurements and the calculation of 3D coordinates were carried out by using the software developed by the authors. It allows loading image data in an arbitrary format, zooming, point measuring, taking lens distortion into consideration, carrying out the relative and absolute orientation, and computing coordinates of an arbitrary point with the control of the transverse parallax. The results, i.e., 3D coordinates of the points, are written to a text file. To find out what processes occur during rolling, it is necessary to acquire a large number of images and, consequently, to take numerous measurements on digital images. Thus, there is a need to automate the process of measuring the markers on the rolled object. Numerous tests were carried out using the Matlab programming environment. Two methods of measurement were tested: 1) to detect markers (region filtering) and to measure the center of markers (weighted center of mass); 2) multi-staged thinning on a binarized (using the otsu method) image. The first method, which gave better results, forms the basis of the Test Field Measurement Field Box software intended as providing automatic measurement of calibration images in a test field. However, further work on automation of strongly deformed model in which the markers lose their circular shape, is recommended. - Źródło:
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Archiwum Fotogrametrii, Kartografii i Teledetekcji; 2008, 18b; 589-600
2083-2214
2391-9477 - Pojawia się w:
- Archiwum Fotogrametrii, Kartografii i Teledetekcji
- Dostawca treści:
- Biblioteka Nauki
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