Convert GML to TOPOJSON Online - Free & Fast

What is GML?

GML (Geography Markup Language) is the OGC standard XML grammar for encoding geographic features with full coordinate reference system support.

What is TOPOJSON?

TopoJSON is an extension of GeoJSON that encodes topology, sharing boundary arcs between adjacent features to dramatically reduce file size for map data.

When Should You Use GML vs TOPOJSON?

GML vs TOPOJSON: Key Differences

• •The core technical difference: GML relies on lossless compression whereas TOPOJSON uses lossy compression.
• •Moving from GML (lossy) to TOPOJSON (lossy) means the output file will be significantly smaller — but at the cost of some visual fidelity.
• •How transparency is handled: TOPOJSON does not support alpha channels — transparent areas in the source will become opaque.
• •File sizes: GML files typically range Larger than Shapefile due to verbose XML structure and TOPOJSON files 80% smaller than equivalent GeoJSON for administrative boundaries.
• •Primary audience: GML is built for ogc-compliant geospatial data exchange, enterprise gis scenarios, while TOPOJSON focuses on web choropleth maps, data visualization, boundary simplification — pick the format that matches your output requirement.

Advantages of GML

• ✓GML applies lossless compression specifically calibrated for OGC-compliant geospatial data exchange, enterprise GIS.
• ✓GML enjoys broad native support across operating systems, browsers, and creative tools alike.
• ✓GML guarantees every bit of the original data survives — no approximations, no shortcuts.
• ✓You will find GML support built into virtually every tool that handles OGC-compliant geospatial data exchange, enterprise GIS — no plugins or converters needed.

Advantages of TOPOJSON

• ✓TOPOJSON uses lossy compression tailored for Web choropleth maps, data visualization, boundary simplification.
• ✓TOPOJSON is supported natively on virtually every device, browser, and operating system.
• ✓TOPOJSON files are compact and quick to transfer, even over slow connections.
• ✓TOPOJSON integrates seamlessly with all major creative tools and workflows.

Common Use Cases for GML to TOPOJSON Conversion

Industry Applications

Best Practices for GML to TOPOJSON Conversion

• →When converting GML to TOPOJSON: confirm the coordinate reference system (CRS / projection) is preserved or explicitly reprojected
• →Keep attribute tables and feature metadata intact — TOPOJSON should retain all fields from GML
• →Check geometry types (point, line, polygon) map cleanly between the two formats
• →Verify that z/elevation values and topology survive the conversion when working with terrain data
• →Always keep a backup of your original files before converting
• →Choose the appropriate quality settings for your specific use case

Troubleshooting GML to TOPOJSON Conversion

• !TOPOJSON features land in the wrong place after GML to TOPOJSON → verify the CRS/projection; mismatched coordinate systems shift geometry
• !Attribute columns missing in TOPOJSON → some GIS formats have field name length or type limits; rename or cast columns first
• !GML to TOPOJSON drops the z/elevation dimension → pick a target format that supports 3D geometry
• !TOPOJSON file won't open in your GIS app → confirm the format version and any required sidecar files (e.g. .prj, .shx) are present

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