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Analiza dokładności kalibracji obrazu cyfrowego na przykładzie mapy wyrobisk górniczych

Mierzejewska A.

Przegląd Górniczy

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2018

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T. 74, nr 8

59--63

PL

Jednym z etapów związanych z wdrażaniem map górniczych w formie numerycznej w przedsiębiorstwach zajmujących się działalnością górniczą jest kalibracja. Jest to proces polegający na nadaniu przestrzennej orientacji obrazom rastrowym z jednoczesnym usunięciem pewnych zniekszałceń. Z etapem tym wiąże się również pewien poziom dokładności określany metodą średniego błędu tranformacji. Na jego wielkość mają wpływ różne czynniki, w tym m.in. przyjęta metoda transformacji, liczba punktów dostosowania oraz ich rozmiesczenie w obrębie arkusza mapy. Biorąc to pod uwagę autorka przeanalizowała kilka wariantów kalibracji mapy wyrobisk górniczych pod względem dokładności w zależności od liczb oraz rozmieszczenia punktów. Proces kalibracji przeprowadzono w programach Geolisp oraz C-GEO, metodą Helmerta.

EN

Calibration is one of the stages related to the implementation of mining maps in the numerical form of mining companies. It is a process of giving spatial orientation to raster images with simaultaneous removal of some distortions. This stage also involves a certain level of accuracy expressed by means of the average error of transformation. Its size is influenced by various factors, including adopted transformation method, number of adjustment points and their placement within the map sheet. Taking this into consideration, the author analyzed several variants of calibration of the mining excavation map in terms of accuracy depending on the number and distribution of points. The calibration process was carried out in the Geolisp and C-GEO programs by use of the Helmert method.

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The process of map calibration and its impact on the quality and accuracy of cartographic materials

Klapa P.

Geomatics, Landmanagement and Landscape

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2018

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no. 1

33--43

EN

The calibration process is a procedure that enables adjusting the scanned portion of the map to the current frame of reference, and equipping it with cartometric properties. As a result of the said process, the raster image becomes cartographic material that can be applied, among others, to the context of geodetic work. There are numerous methods of image transformation and ways of selecting the control points, according to which this process can be carried out. In the paper, the authors present the literature review featuring various problems related to the map calibration process, as well as the methods of transformation, and the ways of selecting the control points. The work was carried out in reference to the example of scanned fragments of cadastral maps, which were then subjected to calibration processes using crosses of map graticule lines and based on situational details. The calibration process was carried out several times using a different number of adaptation points while changing their location and the manner of selection.

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Problemy kalibracji mapy szczegółowej Polski w skali 1:25 000 Wojskowego Instytutu Geograficznego w Warszawie

Panecki T.

Polski Przegląd Kartograficzny

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2014

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T. 46, nr 2

162--172

PL

W artykule omówiono sposoby kalibracji mapy szczegółowej Polski WIG. Z uwagi na dużą liczbę arkuszy do przetworzenia (prawie 1400), głównym założeniem było maksymalne zautomatyzowanie procedury. Za pomocą wygenerowanego indeksu przestrzennego o oczkach siatki odpowiadających podziałowi arkuszowemu mapy i w odpowiednim układzie odniesienia, ręcznie uzyskano informacje o współrzędnych geograficznych z narożników arkuszy, po czym zastosowano skrypt, za pomocą którego dopasowano arkusze do indeksu przestrzennego. Problemem okazał się niejednolity układ odniesienia mapy szczegółowej 1:25 000. Po nieudanej próbie kalibracji w układ „Borowa Góra", podzielono arkusze według obszarów byłych zaborów i zastosowano układy odniesienia charakterystyczne dla każdego z nich - „Deutsches Hauptdreiecksnetz" (DHDN) dla pruskiego, „Hermannskogel" dla austriackiego elipsoidę Żylińskiego dla rosyjskiego. Z uwagi na wciąż niezadowalające efekty, wydzielono dodatkowe obszary, na których zastosowano układ DHDN i „Borowa Góra", minimalizując dotychczasowe błędy kalibracji.

EN

The article aims to present a method of semi-automatic calibration of a detailed map of Poland in 1:25,000 published in 1920s and 1930s by the Military Geographical Institute in Warsaw. The necessity of semi-automatic calibration results from the large numberof sheets (approx. 1400) which madę manuał processing impractical. Although geo-reference was determined for all available sheets (1339), only seven of them are ana-lyzed in the research paper: two from the former Austrian section of partitioned Poland (P51 S32 D „Muszyna", P50 S41 F „Zbaraż-Południe"), two from the former German section (sheet P38 S26 C „Krusz¬wica", P30 S27 F „Hel") and three from the former Russian section (P38 S27 A „Bachorce", P30 S40 H „Skorbuciany", P39 S32 H „Warszawa-Praga"). High level of detail of the map in 1:25,000 resulting from precise field measurements was assumed during the process of calibration. Thus, four control points in map corners together with their geographic coordination and pixel coordinates (x,y) should be sufficient for correct calibration. Scale, shift and rotate raster transformations were used. Automation of calibration involved generating a spa-tial index in the form of a vector grid (polygon-type object) with a single field relating to the sheet division of the map in 1:25,000, i.e. 5'»10'. After adding sheet designation to the grid, a connection between the index (vector grid with sheet designation) and map seans was established. After that geographic coordinates from sheet corners were "manually" read and entered into the database. With the spatial index including automatically obtained geographic coordinates, "manually" read geographic coordinates from sheet corners and the relation between the grid fields and the corresponding *.jpg file, it was possible to execute calibration. The script applied in the process automatically matched scanned sheets to corresponding grid fields, i.e. determined their reference system, pro¬jection and geographic coordinates. After acquiring geo-referential data, each file was transformed into a WGS-84 elipsoid. Map calibration to the "Borowa Góra" system did not bring good results, only the quality of the "Skorbuciany" sheet was sufficient (fig. 1). The contents of the remaining sheets was considerably shifted (by 200-300 m). In order to increase the calibration's precision, map sheets were divided according to the areas of former anexions of Poland and their respective reference systems were employed - "Deutsches Hauptdreiecksnetz" (DHDN) for the former German section, "Hermannskogel" for the Austrian section and Żylinski's ellipsoid for the Russian section. The "Hel" and the "Kruszwica" sheets from the area of the former German section were properly calibrated to the DHDN system (fig. 2), but the contents of the remaining sheets was significantly shifted (figs. 3 and 4). Considering the fact that the effects of calibration were still insufficient, additional areas were distinguished, on which the "DHDN" and the "Borowa Góra" systems were applied thus minimizing previous mistakes. About 70 % of the sheets of the map in 1:25,000 were properly calibrated.