Charge-coupled device
Also called: CCD · Topic: Remote Sensing, GIS and GNSS · NCERT: Class 12, Ch 4 "Spatial Information Technology"
Meaning
A charge-coupled device (CCD) is a small light sensor made of semiconductor material, the kind of material used in computer chips. Many CCDs are set out in rows to form an array. When light falls on them, they turn the light particles (photons) into counts of electrons. Each count is stored as a digital value. This is how a scanner or digital camera turns a picture into numbers a computer can store and process.
Example
A Survey of India paper toposheet of Dehradun, Uttarakhand, is placed on a map scanner. CCDs inside the scanner read the light reflected from each tiny part of the sheet. The sheet becomes a digital raster image, a grid of cells, that can be used in a GIS.
Don't confuse with
- Scanner: a scanner is the whole machine that turns a paper map into an image. The CCD is the sensor inside it that actually records the light.
Related concepts
- Raster data model
- Vector data model
- Topology
- Digitisation
- Scanner
- Georeferencing
- Raster-vector conversion
- Exact matching
- Hierarchical matching
- Fuzzy matching