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https://github.com/geoarrow/geoarrow

Specification for storing geospatial data in Apache Arrow
https://github.com/geoarrow/geoarrow

apache-arrow geoarrow geospatial

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Specification for storing geospatial data in Apache Arrow

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README 

        

# GeoArrow Specification



This repository contains a specification for storing geospatial data in Apache Arrow

and Arrow-compatible data structures and formats.



The [Apache Arrow](https://arrow.apache.org/) project specifies a standardized

language-independent columnar memory format. It enables shared computational libraries,

zero-copy shared memory and streaming messaging, interprocess communication, and is

supported by many programming languages and data libraries.



Spatial information can be represented as a collection of discrete objects using points,

lines and polygons (i.e., vector data). The

[Simple Feature Access](https://www.ogc.org/standards/sfa) standard provides a widely

used abstraction, defining a set of geometries: Point, LineString, Polygon, MultiPoint,

MultiLineString, MultiPolygon, and GeometryCollection. Next to a geometry, simple features

can also have non-spatial attributes that describe the feature.



Geospatial data often comes in tabular format, with one or more columns with

feature geometries and additional columns with feature attributes. The Arrow columnar

memory model is well-suited to store both vector features and

their attribute data. The GeoArrow specification defines how the vector features

(geometries) can be stored in Arrow (and Arrow-compatible) data structures.



This repository contains the specifications for:



- The memory layout for storing geometries in an Arrow array ([format.md](./format.md))

- The Arrow extension type definitions that ensure type-level metadata (e.g., CRS) is

  propagated when used in Arrow implementations ([extension-types.md](./extension-types.md))



Defining a standard and efficient way to store geospatial data in the Arrow memory

layout enables interoperability between different tools and ensures geospatial tools can

leverage the growing Apache Arrow ecosystem:



- Efficient, columnar file formats. Leveraging the performant and compact storage of

  Apache Parquet as a vector data format in geospatial tools using

  [GeoParquet](https://github.com/opengeospatial/geoparquet/)

- Accelerated between-process geospatial data exchange using Apache Arrow IPC message

  format and Apache Arrow Flight

- Zero-copy in-process geospatial data transport using the Apache Arrow C Data Interface

  (e.g., GDAL)

- Shared libraries for geospatial data type representation and computation for query

  engines that support columnar data formats (e.g., Velox, DuckDB, and Acero)



## Relationship with GeoParquet



The GeoParquet specification originally started in this repo, but was moved out into its

own repo (https://github.com/opengeospatial/geoparquet), leaving this repo to focus on

the Arrow-specific specifications (Arrow layout and extension type metadata). Whereas

GeoParquet is a file-level metadata specification, GeoArrow is a field-level metadata

and memory layout specification that applies in-memory (e.g., an Arrow array), on disk (e.g., using

Parquet readers/writers provided by an Arrow implementation), and over the wire (e.g.,

using the Arrow IPC format).



## Implementations



* [geoarrow-c](https://github.com/geoarrow/geoarrow-c): geospatial type system and

  generic coordinate-shuffling library written in C with bindings in C++, R, and Python

* [geoarrow-rs](https://github.com/geoarrow/geoarrow-rs/): Rust implementation of the

  GeoArrow specification and bindings to GeoRust algorithms for efficient spatial

  operations on GeoArrow memory. Includes JavaScript (WebAssembly) bindings.

* [geoarrow-python](https://github.com/geoarrow/geoarrow-python): Python bindings to geoarrow-c

  and geoarrow-rs that provide integrations with libraries like pyarrow, pandas, and

  geopandas.

* [geoarrow-wasm](https://github.com/geoarrow/geoarrow-rs/blob/main/js/README.md):

  WebAssembly module based on geoarrow-rs