The process of conversion of paper maps into digital format usable by computer is known as Scanning. It is used to convert an analog map into a scanned file, which is again converted to vector format through tracing. Scanning automatically captures map features, text and symbols as individual cells, or pixels and produces an automated image.
The scanned file shows map features as raster lines (a series of connected pixels). And must be vectorized to complete the process of digitizing. Vectorization is converting raster lines into vector lines in a process known as tracing.
Based on the document, Scanning is mainly of two types:
Black and White Raster Scanning: It is the simplest type of scanning and can be used on line drawings, text or any one colored document. It is used in Archival Drawing Libraries, Electronic Document Distribution and Vectorization Templates.
Grey Scale and Color Raster Scanning: It is used for large size documents. Its applications include capturing images for use in desktop publishing, full color maps, aerial photography, Toposheets and cartographic base data for “high end” mapping system.