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Not all National Topographic System maps strictly follow the National Tiling System's linear grid. Some maps also, as an "overedge", cover land in an area which would otherwise be covered by an adjacent map sheet, simply because the latter area does not contain enough land in Canada to warrant a separate printing. [4] [clarification needed]
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 quads or quadrangles. Topographic maps conventionally show topography, or land contours, by means of contour lines.
The National Topographic System is used by Natural Resources Canada for providing general purpose topographic maps of the country. The maps provide details on landforms and terrain, lakes and rivers, forested areas, administrative zones, populated areas, roads and railways, as well as other man-made features. [ 22 ]
The same process can be done on a computer, sketching the watershed boundary (with a mouse or stylus) over a digital copy of a topographic map. [1] This is referred to as "heads up digitizing" or "on-screen digitizing." [2] Example of an idealized watershed boundary, drawn on a topographic map with elevation contours.
A contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes. [4] The contour interval of a contour map is the difference in elevation between successive contour lines. [5] The gradient of the function is always perpendicular to the contour ...
The Tanaka (relief) contours technique is a method used to illuminate contour lines in order to help visualize terrain. Lines are highlighted or shaded depending on their relationship to a light source in the Northwest. If the object being illustrated would shadow a section of contour line, that contour would be represented with a black band.
The Centre for Topographic Information produces topographic maps of Canada at scales of 1:50,000 and 1:250,000. The full map catalogue is known as the National Topographic System (NTS). [ 16 ] A government proposal to discontinue publishing of all hardcopy or paper topographic maps in favor of digital-only mapping data was shelved in 2005 after ...
The USGS calls maps based on topographic surveys, but without contours, "planimetric maps." These maps show not only the contours, but also any significant streams or other bodies of water, forest cover , built-up areas or individual buildings (depending on scale), and other features and points of interest.