How do I fix a GeoJSON file that crosses the antimeridian using Python?

Install antimeridian via pip, then use `antimeridian.fix_geojson()` on your GeoJSON dictionary. For batch processing, install the CLI extras and run `antimeridian fix input.json > output.json` from the terminal.

What's the difference between antimeridian and general geometry libraries like shapely?

antimeridian is specialized for splitting geometries at the 180th meridian to ensure GeoJSON compliance, whereas shapely provides broader geometric operations but doesn't handle antimeridian crossings natively. It's a niche tool for a specific problem.

Does antimeridian work with large datasets or is it too slow?

While efficient for typical use, the splitting algorithm involves computational geometry that may not scale well to massive datasets; performance depends on geometry complexity, so testing with your data is advised.

How to handle antimeridian issues in JavaScript instead of Python?

Use the TypeScript port available at https://github.com/krisaoe/antimeridian-ts, which offers similar functionality for Node.js or browser-based geospatial applications.

Can antimeridian fix geometries in shapefiles or do I need to convert first?

No, it only supports GeoJSON, Shapely objects, and __geo_interface__; you must convert shapefiles or other formats to one of these compatible types before using the library.

What happens to properties in GeoJSON features when antimeridian splits them?

Properties are preserved in the corrected features; the library ensures data integrity by retaining all metadata after splitting geometries, as per GeoJSON standards.

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antimeridian

Apache-2.0Pythonv0.4.8

A Python library that fixes GeoJSON geometries crossing the 180th meridian (antimeridian) by splitting them into valid shapes.

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What is antimeridian?

antimeridian is a Python library that corrects GeoJSON geometries crossing the 180th meridian (antimeridian). It solves a common problem in geospatial data where shapes that span the antimeridian become invalid and cause rendering issues in mapping systems, by algorithmically splitting them into valid, standards-compliant geometries.

Target Audience

Geospatial developers, data engineers, and GIS professionals working with GeoJSON data that spans international date lines or global extents, particularly those using Python-based mapping or analysis tools.

Value Proposition

Developers choose antimeridian for its focused, robust solution to a specific geospatial data integrity issue, its support for multiple geometry formats (Shapely, GeoJSON), and its utility functions for bounding boxes and centroids, all backed by a documented algorithm and cross-language ports.

Overview

Correct GeoJSON geometries that cross the 180th meridian

Use Cases

Best For

Preprocessing GeoJSON data for web mapping libraries that don't handle antimeridian crossings
Fixing geometries in global-scale GIS applications before analysis or visualization
Ensuring GeoJSON compliance for data pipelines and APIs
Correcting satellite or sensor data that spans the 180th meridian
Batch processing large geospatial datasets with antimeridian issues
Integrating antimeridian correction into Python-based geospatial workflows

Not Ideal For

Projects dealing exclusively with local or regional geometries that never approach the 180th meridian
Systems requiring real-time geometry correction at millisecond latency for streaming data
Workflows heavily reliant on non-Python geospatial formats like Shapefiles or KML without prior conversion to GeoJSON
Applications that must preserve the exact original coordinate sequence without any geometric modification or splitting

Pros & Cons

Pros

Multi-format Flexibility

Supports Shapely objects, GeoJSON dictionaries, and any object with __geo_interface__, making it adaptable to diverse geospatial workflows without format lock-in.

Efficient In-place Correction

The fix_geojson function mutates input dictionaries by default for performance, with copy options to preserve originals, optimizing memory usage in batch processing.

Comprehensive Geospatial Utilities

Includes specialized utilities for bounding boxes and centroids of antimeridian-crossing shapes, aiding in post-correction analysis and visualization.

Cross-language Portability

Core algorithm has been ported to TypeScript and Go, demonstrating reliability and enabling integration into non-Python tech stacks for broader adoption.

Cons

Heavy Dependency Chain

Relies on shapely and numpy, which are large packages that can bloat projects or complicate deployments in lightweight environments.

Limited Geometry Scope

Only handles polygons, multipolygons, linestrings, and multilinestrings; points or other geometry types that cross the antimeridian are not supported, as noted in the documentation.

Mutation Risk in Default Use

In-place mutation of GeoJSON dictionaries can lead to accidental data loss if users forget to copy inputs, requiring extra caution in error-prone code.

Frequently Asked Questions

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