Background knowledge

Data Domain

The domain of Geographic Information Systems (GIS) and Location Information in general is commonly divided in two different categories of spatial data types: Vector and Raster. Both represent spatial data but they differ significantly: vector is a model that identifies a discrete representation of the entities with a spatial extent in the earth surface while the raster model is only intended for a continuous representation of the data.

Vector Data

Vector data represents geographical features as discrete points, lines, and polygons.

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Raster Data

Raster data represents features as a rectangular matrix of square cells (commonly known as pixels) that are organized into rows and columns.

Each cell contains a value that represents data. The area covered by each pixel determines the spatial resolution of the raster model from which it is derived. The resolution is determined by measuring one side of the square pixel.

Locations

Ubiquitous Language

It's also important to understand the terminology adopted at WFP and the glossary of terms used to refer to the domain of location information in the Organization.

Adopt an ubiquitous language

We are constantly trying to use synonyms in our communications to avoid the repetitions of words, it's a common practice. Software development is not special. Ubiquitous Language is a Domain Driven-Design for the practice of building up a common, rigorous language between developers and users

For this reason, we have created a mapping table with the vast majority of the terms that can be considered similar for a given layer:

GEFS term	Common GIS term	Common term for aggregated levels	General term	Notes
Country	Admin0	Boundaries, Administrative Areas or Units	Geographical master data, locations data
Region	Admin1	Boundaries, Administrative Areas or Units	Geographical master data, locations data
Province	Admin2	Boundaries, Administrative Areas or Units	Geographical master data, locations data
Municipality	Admin3	Boundaries, Administrative Areas or Units	Geographical master data, locations data
Settlement	Admin4	Boundaries, Administrative Areas or Units	Geographical master data, locations data
City	Locations, Places	Cities, Locations	Geographical master data, locations data
Point of Interest	Locations, Places	Points of Interest, Locations	Geographical master data, locations data	Here we have a child level of granularity (Schools, Final Delivery Points, Storage Locations, etc)