Wikipedia:Graphics Lab/Resources/QGIS/Get ready: Difference between revisions
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[[file:QGis_ETOPO1_vs_SRTM3_-_quality_match.jpeg|thumb|600px|Quality comparison between ETOPO1 (pixelated) and SRTM3 (smoother) data sets. This difference doesn't matter for making large maps with coverage greater than 1000km (~620mi) across.]]
* {{Cite GIS |name=ETOPO1 |url_download=http://www.ngdc.noaa.gov/mgg/global/global.html |publisher=[[NGDC]]-[[NOAA]] |year=2009 |license= Public ___domain |tag= standard |url_doc=http://www.ngdc.noaa.gov/mgg/global/etopo1sources.html |layers=topography & bathymetry |precision_max=1850m (1minute arch) |covered_area= all Earth (90N-90S, landmass & sea floor) |datum=WSG 84 |projection = (?) |extensions=.zip → .tif and others |size_compressed=326Mo |size_uncompressed=900Mo |tile_size=whole earth |tiles_total= 1 |comment = Perfect for very large maps (ex: > France). Download: [http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO1/data/ice_surface/grid_registered/georeferenced_tiff/ ETOPO1 Ice Surface (grid registered)], [http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO1/data/bedrock/grid_registered/georeferenced_tiff/ ETOPO1 Bedrock (grid-registered)]. nb: ETOPO1 is a better data than ETOPO2 (lower quality). |editor_note= Please download a ''grid-registered, georeferenced tiff'' in either Ice Surface or Bedrock and unzip it into your ''Data_ETOPO1'' folder.}}
* {{Cite GIS |name= SRTM3 |url_download= http://demex.cr.usgs.gov/DEMEX/ |publisher= NASA / USGS |year= 2000 |license= Public Domain |tag= standard |url_doc= http://dds.cr.usgs.gov/srtm/version2_1/Documentation/SRTM_Topo.pdf |layers= topography |precision_max= 93m (3"arch) |covered_area= 60⁰N-56⁰S (landmass only) |datum= WGS 84 |extensions= .tif |size_compressed= |size_uncompressed= |tile_size= on command |tiles_total= 1 |comment = Perfect for small areas anywhere in the world. Need to create a free account. Worth it. You will use this source frequently. NB: since GIS data are quite heavy (SRTM3, Aster), select the smallest area possible. SRTM1 is an equivalant to ETOPO1. |editor_note=}}
{{summarization|title=: Depreciated 'tiles download' approach|1=
Formerly, hight precision topographic GIS datas being too big —about 60GB for the whole Earth—, these datas were split into dozens, hundreds, or thousands small tiles about some MB each. The mapmaker had to find, download, unzip, load the several needed tiles (say 10 tiles for Danemark), and manage these 10 tiles in parallel for color styles, effects, etc. However, the process is a more complex than downloading a single file. You will need to:
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