COD-ABs for some countries are available with an alternate edge-matched version (COD-AB-EM) as well as the original definitive version.
COD-ABs remain the definitive, accepted, best-available administrative boundary sets for each country. However, COD-AB-EM layers may be more suitable for cartographic visualizations and might also be useful for topological analysis of lower administrative level international connectivity.
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Edge-matched COD-AB-EM layers (administrative level 0 shown) and UN Geo Hub 1:1m boundary (orange)
Edge-matched COD-AB (COD-AB-EM) user stories
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Definitive AB strength
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Edge-matched AB strength
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Definitive AB risk
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Definitive edge-matched risk
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I am an Doctors without Borders provider and need to prioritize where to deploy. This site says there are four doctors deployed to location A and three doctors deployed to location B. I am an obstetrician, does location B automatically need my attention first?
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In-country location comparisons are making more accurate and visual sense
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Usually locations compared are across regions and more suited for performance across device types and conditions
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Cartographic for regional evaluation. Performance for device types and locations
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[more coming soon!]
Edge-matched COD-AB (COD-
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EM) questions and answers
What are COD-AB-EMs?
COD-AB-Ems EMs are copies of the original definitive COD-AB that have had their external feature polygons extended or shrunk to fit the United Nations Geo Hub 1:1m boundary. They therefore fit the COD-AB-EM of neighbouring countries, when available. They may be suitable for cartographic visualizations and might also be useful for topological analysis of lower administrative level international connectivity.
Where can COD-AB-Ems EMs be found?
COD-AB-EMs are included in the normal COD-AB separate datasets on HDX . The containing the gazetteer from the COD-AB-EM resources are included at the bottom of the list on each dataset page. ITOS live geoservices are also available, a zipped folder of shapefiles, a zipped geodatabase, and the ITOS live geoservice.
How can I find which countries have COD-AB-EmsEMs?
The matrix in the “COD-AB features” Feature Suite” page of the COD Portal [SOON TO COME] has a ‘COD-AB-EM’ ‘Edge-matched boundaries’ column that indicates which countries have COD-AB-Ems. COD-AB-EMs are prepared for some of the countries with ITOS geoservices as indicated in the ‘Geoservices’ column in the main page matrix. No countries lacking Geoservices have COD-AB-EMs.
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How are the COD-AB-EMs created?
ITOS merges two line layers, one made from the lowest COD administrative level polygons and the other made from the United Nations Geo Hub 1:1m boundary polygons. COD lines are clipped when overlapping the UN boundary and extended when needed. Care is used in this step to not simply extend the line straight forward to the boundary but to determine where the border would logically continue.
A polygon layer is created from the lines after cleaning their topology errors. Single-part points created from exploded multipart polygons in the COD are then spatially joined to the polygons for attribution. All multipart polygons are dissolved to match the number of admin features in the COD-AB. This layer is then dissolved to create the higher administrative boundary layers.
Are edge-matched COD-ABs EMs authoritative?
Yes, for all attribute (name and P-code) information. COD-AB-EMs and the definitive COD-ABs have the same feature sets and gazetteers. However, the geometry of outer polygons may have been compromised.
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What administrative levels are available?
COD-AB-EMs contain the same administrative levels as the definitive COD-ABs. For instance, the Côte d'Ivoire - Subnational Administrative Boundaries dataset extends to administrative level 3 for both the definitive COD-AB and the COD-AB-EM.