(CityJSON == CityGML) && (CityGML == CityJSON)

Transcript

1. (CityJSON == CityGML)
   
   
   &&
   
   
   (CityGML == CityJSON)
   
   
   Geonovum sessie over 3D
   
   
   Amersfoort
   
   
   2023-10-03
   Hugo Ledoux
   
   
   TUDelft
   

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2. (CityJSON == CityGML)
   
   
   &&
   
   
   (CityGML == CityJSON)
   
   
   Geonovum sessie over 3D
   
   
   Amersfoort
   
   
   2023-10-03
   Hugo Ledoux
   
   
   TUDelft
   Full disclosure:
   
   
   I started CityJSON and I’m still an editor
   

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3. 2
   International standard (from OGC) for representing
   and storing semantic 3D city models
   v1.0 in 2008
   
   
   v2.0 in 2012
   
   
   v3.0 in 2021 & 2023
   

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4. 3
   Data model
   XML/GML encoding
   4 encodings
   3D City DB
   cjdb
   

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5. 4
   Data model == UML Encoding == XML or JSON or …
   {
   
   
   "type": “CityJSON",
   
   
   "version": “2.0”,
   
   
   "transform": {
   
   
   "scale": [1.0, 1.0, 1.0],
   
   
   "translate": [0.0, 0.0, 0.0]
   
   
   },
   
   
   "metadata": {
   
   
   "referenceSystem": "https://www.opengis.net/def/crs/EPSG/0/7415"
   
   
   },
   
   
   "CityObjects": {
   
   
   "id-1": {
   
   
   "type": "Building",
   
   
   "attributes": {
   
   
   "measuredHeight": 22.3,
   
   
   "owner": “Elvis Presley"
   
   
   },
   
   
   "geometry": [
   
   
   {
   
   
   "type": “MultiSurface",
   
   
   "lod": “2.1",
   
   
   "boundaries": [ [[0, 3, 2, 1]], [[4, 5, 6, 7]], [[0, 1, 5, 4]] ]
   
   
   }
   
   
   ]
   
   
   }
   
   
   },
   
   
   "vertices": [
   
   
   [231, 2321, 11],
   
   
   [1111, 321, 12],
   
   
   ...
   
   
   ],
   
   
   "appearance": {
   
   
   "materials": [],
   
   
   "textures":[]
   
   
   }
   
   
   }
   
   
   

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6. CityGML v3.0
   5
   • Adds interior of buildings (rooms,
   storeys, etc)
   
   
   • no more LoD4
   
   
   • Adds point clouds, versioning, etc.
   
   
   • Revamp of the ADE mechanism
   Data model released in 2021
   

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7. CityGML-XML v3.0
   6
   XML encoding released in June 2023
   • No software support at the
   moment: FME will **not** work
   
   
   • Except citygml4j (from the main
   CityGML developer)
   

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8. CityGML files are very complex
   7
   • files are deeply nested, and large
   
   
   • many “points of entry”
   
   
   • many di
   ff
   ways to do one thing
   ➡ few software packages correctly read/write CityGML-XML
   
   
   ➡ no parsers in JavaScript
   
   
   ➡ I personally get 😩 each time I get a new file
   it makes the life of
   developers very
   unpleasant
   

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9. CityGML files are very complex
   7
   • files are deeply nested, and large
   
   
   • many “points of entry”
   
   
   • many di
   ff
   ways to do one thing
   ➡ few software packages correctly read/write CityGML-XML
   
   
   ➡ no parsers in JavaScript
   
   
   ➡ I personally get 😩 each time I get a new file
   it makes the life of
   developers very
   unpleasant
   

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10. v2.0
    
    
    just released!
    Approved by
    
    
    CityGML v3.0
    conformant
    

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11. CityJSON v2.0 implements most of CityGML data model
    9
    • all core modules of CityGML data model v3.0 are mapped 💪
    
    
    • Subset of CityGML core (~97% of features)
    
    
    • Modules not supported is on purpose (to keep it simple)
    

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12. GIS specialists do not all use/have FME: Python parsing is very easy
    10
    CityJSON makes developers
    happy (and thus productive)
    

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13. It’s ready for the web
    11
    

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14. It’s ready for the web
    11
    

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15. Compression of files: Zürich LoD2 buildings
    12
    CityGML-XML v2.0 = 3.0GB
    
    
    (but 1GB of spaces/CRs/tabs!)
    CityJSON v2.0 = 292MB
    Compression == 7.1X
    

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16. Compression of files: Zürich LoD2 buildings
    12
    CityGML-XML v2.0 = 3.0GB
    
    
    (but 1GB of spaces/CRs/tabs!)
    CityJSON v2.0 = 292MB
    Compression == 7.1X
    

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17. CityJSON support in software
    13
    Good list of software
    
    
    Most are open-source
    
    
    Many written by students at TUDelft
    

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18. (CityJSON == CityGML)
    
    
    &&
    
    
    (CityGML == CityJSON)
    
    
    

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19. citygml4j + citygml-tools
    15
    full conversion CityGML <-> CityJSON
    • Supports CityGML-XML
    v3.0
    
    
    • Bidirectional conversion
    
    
    • Open-source
    

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20. CityJSON 🔄 CityGML
    16
    

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21. CityJSON 🔄 CityGML
    16
    

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22. Certainly it can’t be that simple? Indeed, there are 2 caveats
    17
    #1. ADEs != Extensions #2. CityGML modules not supported in CityJSON
    

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23. thank you.
    [email protected]
    
    
    3d.bk.tudelft.nl/hledoux
    Hugo Ledoux
    https://cityjson.org
    https://citygml.org
    3DBAG has all 10M buildings
    in NL in CityJSON
    

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