map accuracy

map accuracy

(1) (Data West Research Agency definition: see GIS glossary.) The closeness of results of observations, computations, or estimates of graphic map features to their true value or position. Relative accuracy is a measure of the accuracy of individual features on a map when compared to other features on the same map. Absolute accuracy is a measure of the location of features on a map compared to their true position on the face of the Earth. Mapping accuracy standards generally are stated as acceptable error and the proportion of measured features that must meet the criteria. In the case of some plotting and display devices, accuracy refers to tolerance in the display of graphic features relative to the original coordinate file.

(2) (Data West Research Agency definition: see GIS glossary.) The level of allowable error of maps, as applied by National Map Accuracy Standards, is determined by comparing the positions of well-defined points whose locations or elevations are shown on the map with corresponding positions as determined by surveys of a higher accuracy. The accuracy of any map is equal to the error inherent in it as due to the curvature and changing elevations contained in each map from which the map was made, added to or corrected by the map preparation techniques used in joining the individual maps.
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Although statistical validation gives a good overall estimate of map accuracy judged against an independent sample, the spatial distribution of relative error in a map is often of more concern to map users (Heuvelink 2014).
The new ASPRS standards were created by the ASPRS Map Accuracy Standards Working Group, a joint panel under the Photogrammetric Applications Division, Primary Data Acquisition Division and Lidar Division, which was established to assess and update ASPRS map accuracy standards to reflect existing technologies.
Finally, results from each method were reviewed separately and then the amount of each method and map accuracy and were evaluated.
0 provides software-based map accuracy and content enhancement solutions.
Community input of GPS data collection now helps Tele Atlas to detect changes and perfect its maps worldwide to the highest industry standard for map accuracy of five metres or 16 feet or less.
This report from the National Research Council of the National Academies assesses current FEMA flood map accuracy and notes that despite recent conversions to digital media, only 21% of all maps meet or exceed data quality thresholds.
Geological Survey digital ortho quarter quadrangles have a map accuracy of 10 meters.
GPS will help document map accuracy, and global coordinates will record each ball marker, on spreadsheet records and AutoCAD drawings of the site.
Mapping of tillage practices and assessment of map accuracy consist of three steps: 1.
Accuracy will vary due to variables in GPS units, map accuracy, and plotting accuracy.
Traditionally, the relationship between scale and accuracy has been defined by the National Map Accuracy Standard (NMAS).