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Analysis of the possibility of using archival maps as a source of elevation data

Cichociński Piotr

GIS Odyssey Journal

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2021

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Vol. 1, no. 1

177--188

EN

One of the most popular sources of elevation data covering the most of the Earth's surface with spatial resolution of up to 30 m (1 angular second to be exact) is the SRTM model. This terrain model has two main disadvantages: it covers the area of the Earth between the parallels 54°S and 60°N only, and in some mountainous and desert areas there are gaps (voids) in the data. Additionally, it may not be suitable for more detailed visualization and analysis due to their limited accuracy. Therefore, the paper attempts to find an alternative source of elevation data. One of them may be archival maps, on which the terrain is presented by means of contours. By vectorization of such lines and adding respective attributes they can serve as a base for building digital terrain models. Examples of such maps are maps created in the period before World War II by Polish Military Geographical Institute (WIG). Although newer topographic maps or even more accurate spatial databases exist, it is assumed that as official materials WIG maps were not covered by copyright, so they are in public domain, just like SRTM. Conducted research and literature studies have shown that the issue of using contours extracted from archival topographic maps is not unambiguous. The lack of reproducibility in the results obtained does not allow making clear recommendations on the feasibility of using archival maps. Using a contour drawing as the sole source of elevation data, without any control, should be considered risky. On the other hand, it seems possible to use them as supplementary and perhaps refining material, but only in places where consistency with other data can be observed.

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‘Partially compiled’ maps 1:25,000 by Polish Military Geographical Institute (1919–1939)

Kuna J.

Polish Cartographical Review

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2018

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Vol. 50, No. 1

31--46

EN

During the interwar period, an estimated 32–36% of Polish territory was covered by the Polish Military Geographical Institute’s (Pol. Wojskowy Instytut Geograficzny) 1:25,000 detailed map. At the same time, the MGI achieved a full coverage of the country by 1:100,000 tactical map. 50% of tactical map sheets were revised for the 1930s – many covered areas for which no detailed maps had been printed. Considering the fact that 1:100,000 tactical map was updated on the basis of revised 1:25,000 maps, another 17–21% of 1:25,000 detailed map sheets were finished or in progress by the German and Soviet invasion in 1939. The study confirmed additional 4% of 1:25,000 detailed map sheets as ‘partially compiled’ by the MGI and finished by the Germans. Another 17% of detailed map sheets are potentially to be found. Hypotheses, clues and evidence are presented in the paper.

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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.