Editing Topographic map (section)

==Conventions==
{{details|contour lines#Elevation and depth}}
The various features shown on the map are represented by conventional signs or symbols. For example, colors can be used to indicate a classification of roads. These signs are usually explained in the margin of the map, or on a separately published characteristic sheet.<ref>{{cite web |website=Ordnance Survey |url-status=dead |date=Jul 2012 |title=OS Explorer Map / 1:25 000 Scale Colour Raster |url=http://www.ordnancesurvey.co.uk/oswebsite/docs/legends/25k-raster-legend.pdf |archive-url=https://web.archive.org/web/20121101163741/http://www.ordnancesurvey.co.uk/oswebsite/docs/legends/25k-raster-legend.pdf |archive-date=1 November 2012 }}</ref><ref>{{cite web |website=Swisstopo |url=http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/accessories/brochures.parsys.000120.DownloadFile.tmp/symbolsen.pdf |title=symbolsen |url-status=dead |archive-url=https://web.archive.org/web/20110726110548/http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/accessories/brochures.parsys.000120.DownloadFile.tmp/symbolsen.pdf |archive-date=26 July 2011 }}</ref><ref>{{cite web |publisher=United States Geological Survey |url=http://erg.usgs.gov/isb/pubs/booklets/symbols/topomapsymbols.pdf |title=Topographic Map Symbols |archive-url=https://web.archive.org/web/20080910173405/http://erg.usgs.gov/isb/pubs/booklets/symbols/topomapsymbols.pdf |archive-date=10 September 2008 }}</ref>

Topographic maps are also commonly called ''contour maps'' or ''topo maps''. In the United States, where the primary national series is organized by a strict 7.5-minute grid, they are often called or ''[[Quadrangle (geography)|quads]]'' or quadrangles.

Topographic maps conventionally show [[topography]], or land contours, by means of [[contour line]]s. Contour lines are [[curve]]s that connect contiguous points of the same [[altitude]] ([[isohypse]]). In other words, every point on the marked line of 100&nbsp;m [[elevation]] is 100&nbsp;m above mean sea level.

These maps usually show not only the contours, but also any significant [[stream]]s or other bodies of [[water]], [[forest]] cover, built-up areas or individual buildings (depending on scale), and other features and points of interest such as what direction those streams are flowing.

Most topographic maps were prepared using [[photogrammetry|photogrammetric]] interpretation of [[aerial photography]] using a [[stereoplotter]]. Modern mapping also employs [[lidar]] and other [[Remote sensing]] techniques. Older topographic maps were prepared using traditional [[surveying]] instruments.

The cartographic style (content and appearance) of topographic maps is highly variable between national mapping organizations. Aesthetic traditions and conventions persist in topographic map symbology, particularly amongst European countries at medium map scales.<ref>{{Cite journal|last1=Kent|first1=Alexander J.|last2=Vujakovic|first2=Peter|date=August 2009|title=Stylistic Diversity in European State 1 : 50 000 Topographic Maps|journal=The Cartographic Journal|language=en|volume=46|issue=3|pages=179–213|doi=10.1179/000870409x12488753453453|s2cid=129681695|issn=0008-7041}}</ref>