Hierarchical matching
Topic: Remote Sensing, GIS and GNSS · NCERT: Class 12, Ch 4 "Spatial Information Technology"
Meaning
Hierarchical matching links data collected for small areas with data for larger areas. The small areas are added up until they fit the larger units exactly. Then the two datasets can be joined. It is needed because different agencies often collect data at different levels, such as village, block and district. It works only when the small units fit fully inside the larger ones.
Example
A district in Rajasthan has village-wise data on wells but tehsil-wise data on rainfall. The well counts of all villages in each tehsil are added up. The tehsil totals can then be joined with the rainfall data and the two compared.
Don't confuse with
- Exact matching: exact matching joins records for the very same units through a common key, with no adding up.
- Fuzzy matching: this is used when the boundaries do not fit inside one another at all.
Related concepts
- Raster data model
- Vector data model
- Topology
- Digitisation
- Scanner
- Charge-coupled device
- Georeferencing
- Raster-vector conversion
- Exact matching
- Fuzzy matching