Digitization and georeferencing of historical maps. Old maps may contain valuable information about the past. By adding coordinates to such maps, they may be added as a feature layer to modern GIS data. This facilitates comparison of different map layers showing the geography at different times.
Manual digitization by tracing a mouse over features displayed on a computer monitor, used as a method of vectorizing raster data. Referenced by: Geographic information system.
Automatic digitization is another method of digitizing features. The ArcScan for ArcGIS extension enables you to perform automatic or interactive raster-to-vector data conversion with high precision and little or no operator intervention during the data capture stage.
map digitization Conversion of map data from graphic to digital form. map, engineering Map showing information that is essential for planning an engineering project or development and for estimating its cost. It usually is a large-scale map of a small area or of a route.
It is especially useful as it has strong support for digitization. Raw geographic data can be edited in many standard database and spreadsheet applications and in some cases a text editor may be used as long as care is taken to properly format data.
14 Potential ~ Error
Positional errors can also arise when features to be mapped are inherently vague. Take the example of a wetland (Figure 5.15 "Defining a Wetland Boundary"). What defines a wetland boundary?
Manual digitizing: ~ is done directly over the raster by the use of a digitizing tablet, which is a manual pointing device that creates an identical vector map on the computer screen, defining the vertices, points, line data, etc.
digit - Interactive editing and ~ of vector maps.
v.digit [-n] map=name [bgcmd=string]
-n Create new file if it does not exist.
This model had the great advantages of relatively fast data processing and visualization, and because the primary data capture method used in that time was the ~ of maps, the simplified preprocessing of data sources.
Data acquisition may be accomplished through the ~ of existing maps, keyboard entry of attribute data, or by the importation of existing data files. Many GIS packages allow for dynamic file sharing with data from spreadsheet or data base management packages.
[data capture] Manual ~ by tracing a mouse over features displayed on a computer monitor, used as a method of vectorizing raster data.
As discussed in an earlier article, they also specialize in the creation of DEMs from these maps by ~ of contour lines and contour line interpolation. Unfortunately, these maps are not cheap.
To simplify the ~ of maps, degrees of latitude in the southern hemisphere are often assigned negative values (0 to -90°).
The ~ process usually takes around 10 hours to complete and includes over 400 precincts. Changes in the pecinct map are made on a routine basis and involve merging older precincts, in the older, eastern part of Omaha, and adding others to the newer, west part.
The digitizer should concentrate solely on capturing the exact nature of the features. All maps shall be edge matched prior to ~ to eliminate cartographic errors and reduce digital problems.
Geologic Div. (USGS); Geospatial data; Graphic ~
Geographic Data Analysis System ...
Janet Tilley earned her B.S. in Geology and a Certificate in Cartography from George Mason University, Fairfax, Virginia in 1994. She came to USGS from the Department of Agriculture in 1989, where she was working with satellite image interpretation and ~ techniques for over 6 years.
The proper selection of grid spacing determines the level of content thatmay be extracted from a given source during ~. 10 Meter sampling, from 1:24k USGS quad sheets.
SRGStandardized raster graphic, a digital representation of a map or chart, which is captured by automatic ~ (scanning), stored on a digital storage media, and displayed on a raster screen or raster plotter; obtained by a regular scan of a paper map or chart or repromat.
did the source data originate from, what was the scale at which it was prepared, if based on others' work where can this be found, and what are the copyright restrictions involved in its use by a third party? What levels of accuracy were accepted and what errors were recorded during ~ etc?
See also: What is the meaning of Information, GIS, Map, Database, Digital?