If I want to locate the contour line at elevation 105 I determine where the line goes between the two points as follows: On the to-scale map the distance between points is 5 inches. These maps are modeled on the familiar 7.5-minute quadrangle maps of the period 1947-1992, but are mass-produced. The term US Topo refers specifically to quadrangle topographic maps published in 2009 and later.
#Contour map online series#
Let’s say I have two points: Point A, elevation 103.5, and Point B, elevation 107 the map scale is 1 inch equals 10 feet and the distance between points is 50 feet. The maps shown through topoView are from the USGS’s US Topo series and earlier Historical Topographic Map Collection (HTMC). The proportion of distance and the elevation will be used to locate contours between points. The information used is the distance between points and the elevations of the points. An advantage of this method is once the raw data are collected the map can be created back in the office rather trying to do this in the field. Interpolation is a method to locate contours using the raw data collected in the field. After all the elevations have been determined and the points located on a scaled map, contour lines are drawn based on the desired contour interval using interpolation between points of known elevation. The distance between points on the grid can vary but at a scale where 1 inch equals 10 feet a common distance between points is 50 feet. To use the cross-section method, set a control or reference line at the center of the lot, then lay out and stake a grid the elevation is determined at each stake in the grid relative to a benchmark. The two ways to establish a contour map are the cross-section method and the trace contour method. A designer can use this very accurate information as they design a system that fits the site. Once the contour map is created all the major components of the site can be located on the to-scale map. It piggybacks on the open SRTM elevation and OpenStreetMap (OSM) databases. There are two ways you can generate a contour map of the lot. OpenTopoMap OpenTopoMap is the largest crowd-sourced topographic map project in the world. There are times when you will be working on a lot that is not part of a development and the only contour map available are the USGS maps that are not at the scale you need.
#Contour map online how to#
I have discussed previously how to interpret and use a contour map to assist in a site evaluation to decide where to place an onsite systems. Accessing the information you need is easier and quicker than ever.Get Systems/ATUs articles, news and videos right in your inbox! Sign up now.
Filters and searches work seamlessly with the map records table to get you the info you need with fewer clicks. We've added the ability to preview maps within the interface and give you tools to compare any historical map with maps of the present.
#Contour map online full#
The latest version of topoView is full of enhancements based on hundreds of your comments and suggestions. New functionality driven by your feedback Like the historical topographic mapping collection, we've added a variety of file formats previously unavailable for the US Topo series, including GeoTIFF and KMZ. If you have the boundary definition file. Click on Browse button and locate the CSV file from your computer.
The US Topo series is a latest generation of topographic maps modeled on the USGS historical 7.5-minute series (created from 1947-1992). Select Contour option from modules drop down menu. We've added the US Topo series to topoView, giving users access to over 3 million downloadable files from 2009 to the present day. The NGMDB project is proud to assist the NGP in bringing these maps to the Web. Geologic and topographic mapping have a long tradition together (see 1888 report). This interface was created by the National Geologic Map Database project (NGMDB), in support of the topographic mapping program, managed by the USGS National Geospatial Program (NGP). TopoView shows the many and varied older maps of each area, and so is especially useful for historical purposes-for example, the names of some natural and cultural features have changed over time, and the historical names can be found on many of these topographic maps. The most current map of each area is available from The National Map. As the years passed, the USGS produced new map versions of each area. This mapping was done at different levels of detail, in order to support various land use and other purposes. In 1879, the USGS began to map the Nation's topography. TopoView highlights one of the USGS's most important and useful products, the topographic map.
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