Hi everybody,
Back in June I was preparing an exposure model for Attica. This model is describing all buildings and their vulnerability to earthquakes. During this work, I have discovered several little discrepancies between OSM boundaries and the GADM (www.gadm.org) and data from https://geodata.gov.gr/en/dataset/oria-demon-kallikrates. After posting this here, the problems were fixed really quickly.
I’m now expanding the model to all of Greece and therefore I’m checking all boundaries of the admin_level=7 districts. I started with Crete and I found again several discrepancies for which I’m not able to find any confirming information in English:
Case 1: Paximadi
Does Paximadi island belong to Chersonisos? It is currently not assigned to any district (admin_level 7). GADM considers this island to be part of Chersonisos as does geodata.gov.gr.
https://www.openstreetmap.org/relation/873461
Case 2: Glaronisi
Does Glaronisi island belong to Chersonisos? It is currently not assigned to any municipality. GADM and the geodata.gov.gr municipality boundaries (Kallikratis and Kapodistrian) also do not consider this island to be part of Chersonisos.
https://www.openstreetmap.org/relation/873060
Case 3: Agii Pandes and Mikronisi
Do Agii Pandes and Mikronisi islands belong to the Agios Nikolaos district (admin_level 7)? GADM considers this island to be part of Agios Nikolaos as does geodata.gov.gr.
Agii Pandes: https://www.openstreetmap.org/relation/855217
Mikronisi: https://www.openstreetmap.org/relation/890547
Case 4: Vryonisi
Does the island of Vryonisi belong to the district of Agios Nikolaos (admin_level 7)? GADM and geodata.gov.gr considers it to be part of Agios Nikolaos.
https://www.openstreetmap.org/relation/891599
Case 5: unnamed island
According to geodata.gov.gr, this unnamed island should belong to the Agios Nikolaos district (admin_level 7) but it is currently not assigned to any district at the admin_level 7.
https://www.openstreetmap.org/way/505334728
Case 6: unnamed island
According to geodata.gov.gr, this unnamed island belongs to the Ierapetra district (admin_level 7) but it is currently not assigned to any district at the admin_level 7.
https://www.openstreetmap.org/way/505334661
Case 7: Psyllos
According to geodata.gov.gr, the island of Psyllos belongs to the Ierapetra district (admin_level 7) but it is currently not assigned to any district at the admin_level 7.
https://www.openstreetmap.org/relation/892922
Case 8: Konida
The island Konida is assigned to the municipality of Kavousi but not to the district of Ierapetra (admin_level 7). According to geodata.gov.gr, it should also belong to Ierapetra.
https://www.openstreetmap.org/relation/894390
Case 9: Agriomandra
The island Agriomandra is assigned to the municipality of Kavousi but not to the district of Ierapetra (admin_level 7). According to geodata.gov.gr, it should also belong to Ierapetra.
https://www.openstreetmap.org/relation/895148
Case 10: Katergo
The island of Katergo is only assigned to Lasithi regional unit (admin_level 6) but should, according to geodata.gov.gr, be also part of the district of Ierapetra (admin_level 7).
https://www.openstreetmap.org/relation/895666
Case 11: unnamed island
According to geodata.gov.gr, this unnamed island belongs to the Ierapetra district (admin_level 7) but it is currently not assigned to any district at the admin_level 7.
https://www.openstreetmap.org/way/223332259
Case 12: missing islands (rocks)
According to geodata.gov.gr, there are a couple of islands (or rocks) that belong to the district of Ierapetra (admin_level 7). The islands show up on Bing and Google satellite imagery but are not included in OSM.
https://www.openstreetmap.org/?mlat=35.01724&mlon=25.86058#map=19/35.01724/25.86058
Case 13: Grandes West and East islands
The Grandes West island belongs, according to geodata.gov.gr, to the district of Sitia (admin_level 7) but it is currently not assigned to any district at the admin_level 7. Geodata.gov.gr is not assigning Grandes East to any district. Is this correct?
Grandes West: https://www.openstreetmap.org/relation/896167
Grandes East: https://www.openstreetmap.org/relation/896166
Case 14: Anavatis, Kavallos, Kefali islands
The islands of Anavatis, Kavallos, and Kefali belong, according to geodata.gov.gr, to the district of Sitia (admin_level 7) but they are currently not assigned to any district at the admin_level 7.
Anavatis: https://www.openstreetmap.org/relation/896171
Kavallos: https://www.openstreetmap.org/relation/896170
Kefali: https://www.openstreetmap.org/relation/896172
Case 15: Kymo
The Kymo island belongs, according to geodata.gov.gr, to the district of Sitia (admin_level 7) but it is currently not assigned to any district at the admin_level 7.
https://www.openstreetmap.org/relation/896175
Case 16: boundary between Sitia and Ierapetra districts
The boundary between the districts of Sitia and Ierapetra at the admin_level 7 is very different from the same boundary on geodata.gov.gr (the Kallikratis boundary). Geodata.gov.gr and GADM show essentially the same boundary line (see also the boundary on https://en.wikipedia.org/wiki/Lasithi). The boundary in OSM is composed of the two relations
Sitia: https://www.openstreetmap.org/relation/2187435
Ierapetra: https://www.openstreetmap.org/relation/2187433
I would be grateful if somebody can help me with confirming or fixing the cases 1-15. I’m happy to fix them myself, however, I don’t feel comfortable to change boundaries in Greece without consulting the community first as my sources to prove anything here are limited and I don’t understand the copyrights on Greek websites.
If cases 1-15 are not fixed or cannot reasonably be fixed, this would not be a problem as all these little islands seems uninhabited and there will no measurable consequence for the model. However, case 16 is very different: the boundaries in OSM and geodata.gov.gr are many kilometers apart and truly covering different areas. Can somebody explain this discrepancy?
Thanks a lot for your help!
Cheers from Berlin, Germany
-danijel
