We call this spacing the contour interval. In order to keep things simple, topographic maps show lines for certain elevations only. The line you see will look like a contour line on a topographic map.
#Topographic map contour interval how to
Here's a cool way to understand how to interpret contour lines: Take an object like a ball or a pile of laundry, and shine a red laser pointer along the object's side. They're useful because they illustrate the shape of the land surface - its topography - on the map. Contour lines show elevation and the shape of the terrain. Contour lines are lines drawn on a map connecting points of equal elevation, meaning if you physically followed a contour line, elevation would remain constant. © HowStuffWorksĬontour lines are the greatest distinguishing feature of a topographic map.
Geological Survey (USGS) lists the following symbols on its topographic maps:Ĭontour lines help users to see points of equal elevation. Each color means something different.Ī topographic map uses symbols to keep the map less crowded, but it's still chock-full of information. You'll see these lines in many colors - brown, blue, red, black and purple. These lines indicate boundaries, contours, roads, streams and more. Lines on a topographic map can be straight or curved, solid or dashed, or a combination. You'll see big buildings - your local shopping center, for example - as their actual shapes. On these maps, you'll see large expanses of green for vegetation, blue for water and gray or red for densely built up areas. The first step in learning how to read a topographic map is to understand how to interpret the lines, colors and symbols. People use topographic maps for engineering, conservation, environmental management, public works design, urban planning and outdoor activities like fishing, hiking or camping. The advent of airplanes in the 1940s helped to advance mapping techniques.īecause the maps show so much information, they have a wide variety of uses. Then they would plot their maps, with the features that they could see and measure. Mapmakers would find an area's best vantage point - usually the highest point - and climb up to it with drawing boards and sighting devices. Mule pack train was the only way to reach the mostly unsettled West, and cartographer's tools were crude compared with today's. When the USGS first started creating maps - which it did to catalog public land - the process was time-consuming and costly.
Developments in aerial photography and satellite imaging make these maps much more accurate and efficient to produce than in the days when they were created by hand. Geological Survey (USGS) produced its first topographic map in 1879, and it still produces them today.
This contour and elevation information distinguishes them from other maps. These maps show the land's contours, elevations, mountains, valleys, bodies of water, vegetation and more. You can also find information about customized maps, data inventory, and planning and zoning terms and categories.What's the difference between a topographic map and a regular map? In a nutshell, topographic maps allow you to see a three-dimensional landscape on a two-dimensional surface. The (M-NCPPC) Information Management Division has available GIS digital data of Prince George's County in their Open Data site. Digital County Data & Customized Paper Maps The Maryland National Capital Park and Planning Commission’s (M-NCPPC) Information Management Division for Prince George’s County provides all GIS related data and maps to the public for Prince George’s County. We provide support to the Public Safety and Homeland Security agencies with GIS technology and assistance during emergency operations. OIT-GIS is responsible for maintaining the County Enterprise Geodatabase, a GIS data repository containing over 700 layers of County GIS data and imagery compiled from county, municipal, state, and federal agencies. Our Map Depot provides a resource of County information through GIS web applications and digital maps to its citizens and the public. We develop the highest quality GIS data, maps, and GIS applications to enhance their day to day business activities. The Office of Information Technology’s GIS division (OIT-GIS) is an internal service group providing leading edge GIS technology to Prince George’s County agencies. This spatial information is able to help the user make decisions and help resolve issues before "real time" events begins. With a GIS, you can capture spatial information and store it, integrate it, manipulate it, analyze it and display it. A Geographic Information System (GIS) is an automated mapping system that uses computers to help map and analyze data that exist on the earth according to their geographic location.
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