GeoFormatTypes.jl

GeoFormatTypes.GeoFormatTypesModule

GeoFormatTypes

GeoFormatTypes defines wrapper types to make it easy to pass and dispatch on geographic formats like Well Known Text or GeoJSON between packages. This way information about what format is contained is kept for later use, - instead of passing a String or Int that could mean anything.

Wrapper types also allow methods such as convert to work with data in multiple formats, instead of defining lists of format-specific handling methods. Currently ArchGDAL.jl is privileged to define convert methods for GeoFormatTypes.jl objects, using GDAL. When it is loaded, objects can be converted from one format to another:

julia> using GeoFormatTypes, ArchGDAL

julia> convert(WellKnownText, EPSG(4326))
WellKnownText{GeoFormatTypes.CRS, String}(GeoFormatTypes.CRS(), "GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AXIS[\"Latitude\",NORTH],AXIS[\"Longitude\",EAST],AUTHORITY[\"EPSG\",\"4326\"]]")

ArchGDAL.jl is not a direct dependency of GeoFormatTypes.jl, so small packages that handle geospatial formats in some way can depend on GeoFormatTypes.jl without worry about large dependencies.

One complexity of GeoFormat objects is that some formats can hold either CRS (Coordinate Reference System) or geometric data, or even both at the same time.

This is handled using the CRS, Geom and Mixed traits. When the contents are explicitly known to be e.g. crs data, then CRS can be used, for example with all types of well known text:

crs = WellKnownText2(CRS(), crs_string)

If the contents are not known, the default Mixed() will mostly do the right thing anyway - it can be converted to either CRS or geometry formats using convert, given that it is actually possible to do with the contained data.

We thank Julia Computing for supporting contributions to this package.

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GeoFormatTypes.EPSGType
EPSG <: CoordinateReferenceSystemFormat

EPSG(input)

EPSG code representing a coordinate reference system from the EPSG spatial reference system registry.

String input must start with "EPSG:". EPSG can be converted to an Int or String using convert, or another CoordinateReferenceSystemFormat when ArchGDAL.jl is loaded.

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GeoFormatTypes.ESRIWellKnownTextType
ESRIWellKnownText <: AbstractWellKnownText

ESRIWellKnownText(x::String)
ESRIWellKnownText(::CRS, x::String)
ESRIWellKnownText(::Geom, x::String)

Wrapper for Well-Known-Text strings, following the ESRI standard.

These may hold CRS or geometry data. The default mode is Unknown, and conversions to either type will be attempted where possible. A specific type can be specified if it is known, e.g:

crs = ESRIWellKnownText(CRS(), crs_string)
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GeoFormatTypes.GMLType
GML <: MixedFormat

Wrapper for Geography Markup Language string.

These contain geometry data, but may also have embedded crs information. GML can be converted to either a GeometryFormat or CoordinateReferenceSystemFormat.

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GeoFormatTypes.GeoJSONType
GeoJSON <: GeometryFormat

Wrapper for a GeoJSON String or Dict.

Conversion between Dict and String values is not yet handles.

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GeoFormatTypes.GeometryFormatType
GeometryFormat <: GeoFormat

Formats representing geometries. These wrappers simply mark string formats that may optionally be converted to Geoetry objects at a later point.

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GeoFormatTypes.KMLType
KML <: GeometryFormat

Wrapper object for "Keyhole Markup Language" (KML) strings.

See: https://www.ogc.org/standards/kml/

Can be converted to a String. Conversion to crs will convert from EPSG(4326), which is the default for KML.

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GeoFormatTypes.WellKnownBinaryType
WellKnownBinary <: MixedFormat

Wrapper for Well-Known-Binary objects.

These may hold CRS or geometry data. The default mode is Unknown, and conversions to either type will be attempted where possible. A specific type can be specified if it is known, e.g:

crs = WellKnownBinary(CRS(), crs_blob)
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GeoFormatTypes.WellKnownTextType
WellKnownText <: AbstractWellKnownText

WellKnownText(val)
WellKnownText(mode, val)

Weapper for Well-Known-Text v1, following the OGC standard. These may hold CRS or geometry data.

These may hold CRS or geometry data. The default mode is Mixed(), and conversions to either type will be attempted where possible. A specific type can be specified if it is known, e.g.:

geom = WellKnownText(Geom(), geom_string)
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GeoFormatTypes.WellKnownText2Type
WellKnownText2 <: AbstractWellKnownText

WellKnownText2(val)
WellKnownText2(mode, val)

Weapper for Well-Known-Text v2 objects, following the new OGC standard.

These may hold CRS or geometry data. The default mode is Unknown(), and conversions to either type will be attempted where possible. A specific type can be specified if it is known, e.g.:

crs = WellKnownText2(CRS(), crs_string)
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