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This group of maps, which includes the CanMatrix and CanTopo collections, is now a legacy product that is no longer maintained. It may not meet current government standards. Natural Resources Canada's (NRCan) topographic raster maps provide a representation of the topographic phenomena of the Canadian landmass. Several editions of paper maps have been produced over time in order to offer improved products compared to their predecessors in terms of quality and the most up to date information possible. The georeferenced maps can be used in a Geographic Information System (GIS). In all cases, they accurately represent the topographical data available for the date indicated (validity date). The combination of CanMatrix and CanTopo data provides complete national coverage. • CanMatrix - Print Ready: Raster maps produced by scanning topographic maps at scales from 1:25 000 to 1:1 000 000. This product is not georeferenced. Validity dates: 1944 to 2005 (1980 on average). Available formats: PDF and TIFF • CanMatrix - Georeferenced: Raster maps produced by scanning topographic maps at scales of 1:50 000 and 1:250 000. These maps are georeferenced according to the 1983 North American Reference System (NAD 83). Validity dates: 1944 to 2005 (1980 on average). Available format: GeoTIFF • CanTopo: Digital raster maps produced mainly from the GeoBase initiative, NRCan digital topographic data, and other sources. Approximately 2,234 datasets (maps) at scale of 1:50 000, primarily covering northern Canada, are available. CanTopo datasets in GeoPDF and GeoTIFF format are georeferenced according to the 1983 North American Reference System (NAD 83). Validity dates: 1946 to 2012 (2007 on average). Available formats: PDF, GeoPDF, TIFF and GeoTIFF
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[IS] Loftmyndir, sem bandaríski herinn tók á árunum 1956-1961, eru svokallaðar DMA myndir (Defense Mapping Agency). Afrit af filmum DMA myndanna er að finna í loftmyndasafni Náttúrufræðistofnunar (áður Landmælinga Íslands). Árið 2024 voru filmurnar skannaðar af fyrirtækinu Wehrli & Co (í Bandaríkjunum) með 20 míkróna punktstærð og 8-bita dýpt. Staðsetning myndanna var unnin út frá níu kortum í mælikvarðanum 1:250.000. Fluglínur voru upphaflega handteiknaðar á kortin, kortin voru hnitsett og seinna var fluglínunum settar á vektorform, þar sem fyrstu og síðustu myndanúmer hverrar fluglínu voru skráð sem eigindir. Í kjölfariðið var gagnagrunnurinn endurskoðaður með því að rýna skönnuðu myndirnar. Auka upplýsingum var bætt við eigindatöfluna, svo sem dagsetningar ljósmyndanna, brennivídd og flughæð. Fluglínurnar voru einnig flokkaðar eftir staðsetningu og nálægum dagsetningum í eigindinni „svæði“. Hverri fluglínu var umbreytt í punkta, þar sem gert var ráð fyrir að punktarnir væru miðja fyrstu og síðustu mynda fluglínunnar. Staðsetning miðju allra hinna myndanna meðfram viðkomandi fluglínu var línulega áætluð, miðað við að allar myndirnar væru teknar með reglulegu millibili. Áætluð nákvæmni staðsetningar er ± 2 km. [EN] The aerial photographs collected by the US military in 1956-1961 are the so-called Defense Mapping Agency (DMA) images. A copy of the films of the DMA images is available at the archive of aerial photographs of the National Land Survey of Iceland. In 2024, these films were scanned by the company Wehrli & co (in US), at a scanning resolution of 20 microns and 8-bits. The location of these images was extracted by a series of nine maps in 1:250.000 which had hand-drawn the flightlines relative to these images. These maps were georeferenced and the flightlines were digitized into vectors, writing the first and last image numbers of each flightline as attributes. Once this was finished, a revision of the database was made, by inspecting the scanned images. Extra information was added into the table, such as the date of the photographs, the focal length and flight height. The flightlines were also grouped by location and nearby dates, into the attribute "area". Finally, each flightine was converted into points, assuming these points to be the first and last center of the images of the flightline. The location of the center of all the remaining images along a flightline were linearly interpolated, assuming that all the images were taken at regular intervals. The expected accuracy of the geolocation is ± 2 km.