Wikipedia:Graphics Lab/Resources/QGIS/Get ready: Difference between revisions

Revision as of 10:17, 2 December 2012

Revision as of 11:00, 6 April 2013

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* {{GIS data for Graphic Lab |name= SRTM3 (90m) |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. |editor_note= For this tutorial, and since GIS data are quite heavy (SRTM3 90m, Aster 30m), select and download the smallest area possible (Taiwan, Hongkong are good choices with both sea and mountains).}}

{{summarization|title=: Depreciated 'tiles download' approach|1=

Formerly, highthigh 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:

# '''Know''' the coordinates of the area you want to map—although you do have the option of visually selecting the area on the download page.

# '''Find''' the associated GIS files (also called '''tiles'''). SRTM files have names such as "N22E112.hgt.zip", standing for 22⁰ North, 112⁰ East.