Digitisation
Also called: Digitising · Topic: Remote Sensing, GIS and GNSS · NCERT: Class 12, Ch 4 "Spatial Information Technology"
Meaning
Digitisation means turning features on a paper map into digital coordinates (x, y positions) that a computer can store. An operator traces points, lines and boundaries, usually on a digitiser. It is the best way to input vector data, where features are stored as points, lines and polygons. Common errors are omissions (features left out), undershoots (a line stops short of the line it should meet) and overshoots (a line goes past it). These must be corrected before the data is used.
Example
To build a GIS of Aligarh, Uttar Pradesh, an operator traces roads, railway lines and land-use boundaries from a paper land-use map. Each road becomes a line and each land-use patch becomes a polygon.
Don't confuse with
- Scanning: scanning makes a raster picture of the whole map in one go. Digitisation records each feature separately as vector coordinates.
Related concepts
- Raster data model
- Vector data model
- Topology
- Scanner
- Charge-coupled device
- Georeferencing
- Raster-vector conversion
- Exact matching
- Hierarchical matching
- Fuzzy matching