TODO
KOGIS (= Koordination, Geo-Information und Services) is, along with
eCH, the custodian of INTERLIS language/specification. KOGIS coordinates some activities in the
Swiss Bundesverwaltung related to Geoinformation (GI) and GIS
GML is an
XML grammar that allows to express
geographical features. It is defined by the
Open Geospatial Consortium (OGC).
Spaten is a geo data format that purports to resolve issues that arise from using legacy serialization methods and simplify workflows.
WGS84
WGS84 is the latest revision of the WGS (World Geodetic System) standard.
WGS includes
- Definitions of fundamental and derived constants of coordinate systems.
- The Earth Gravity Model (EGM)
- A description of the associated World Magnetic Model (WMM)
- A current list of local datum transformations
Definition
- The origin of the coordinate system is the Earth's center of mass (whose uncertainity is believed to be less than 2cm !)
- The WGS84 meridian of zero longitude is the IERS Reference Meridian, 102 meters or 5.3 arc seconds east of the Greenwich meridian.
- The WGS 84 datum surface is an oblate spheroid with equatorial radius a = 6'378'137 m at the equator and flattening f = 1/298.257'223'563.
Apparently, it is planned to move to IGS20 on 27 November 2022 (not sure if this move has taken place).
INTERLIS
INTERLIS is a software independent description language used for modelling and
exchanging geodata.
FMT
Equal-area projections
The most common global equal-area projections available in GIS include:
- Sinusoidial
- Eckert
- Homolosine
- Mollweide
- Hammer
Discrete Global Grid Systems (DGGS)
A Discrete Global Grid System (DGGS) is a type of spatial reference system that tessellates the globe into many individual, evenly spaced, and well-aligned cells.
Such cells are used to encode location and, thus, can serve as a basis for data cube construction
Open source DGGS implementations include:
- Google S2
- Uber H3: a Hexagonal hierarchical geospatial indexing system.
- RiskAware OpenEAGGR
- rHEALPix by Landcare Research New Zealand (the original intention was to achieve equal-area cells throughout all resolutions)
- DGGRID by Southern Oregon University
HEALPix projection
HEALPix is a projection that is based on subdivisions of a
distorted rhombic dodecahedron (a convex polyhedron with 12 congruent rhombic faces).
When subdividing a level, each tile is divided into four tiles so that at any level of subdivisions, all tiles have the same size.
HEALPix as an acronym or Hierarchical Equal Area isoLatitude Pixelisation (of a 2-sphere).
Sometimes, it is also written as Healpix.
Because of its properties (espciallhy for calculating spherical harmonic transforms), HEALPix is widely used to map the cosmic microwave background.
Alternatives for HEALPix include