Exact matching
Topic: Remote Sensing, GIS and GNSS · NCERT: Class 12, Ch 4 "Spatial Information Technology"
Meaning
Exact matching links two GIS data files about the same set of features. It uses a key that both files share, such as town names. Records with the same key are joined and stored in one file. For example, a map file and a table can be merged so each town carries both its location and its figures. It only works when the key is spelt and coded the same way in both files.
Example
A GIS layer shows the towns of western Uttar Pradesh, such as Meerut, Aligarh and Saharanpur, as points. A separate table lists each town's literacy rate. Matching the two files on town names joins the literacy figures to each town point, so a literacy map can be drawn.
Don't confuse with
- Hierarchical matching: exact matching joins features that are the same units. Hierarchical matching first adds up small units until they fit larger ones.
- Fuzzy matching: this is used when the boundaries of the two datasets do not line up at all.
Related concepts
- Raster data model
- Vector data model
- Topology
- Digitisation
- Scanner
- Charge-coupled device
- Georeferencing
- Raster-vector conversion
- Hierarchical matching
- Fuzzy matching