Convert TOPOJSON to BNA Online - Free & Fast

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.

What is BNA?

Atlas Boundaries (BNA) is a simple ASCII coordinate format for storing polygon boundary data, originally developed by Atlas GIS for representing area features like postal codes, sales territories, and administrative regions as coordinate lists.

When Should You Use TOPOJSON vs BNA?

TOPOJSON vs BNA: Key Differences

• •TOPOJSON uses lossy compression while BNA uses lossy compression — both take the same approach to file size management.
• •Both formats share lossy compression, so quality behavior is similar across the two — file size differences come from algorithm efficiency rather than compression philosophy.
• •Alpha channel support: BNA handles transparency.
• •TOPOJSON files are typically 80% smaller than equivalent GeoJSON for administrative boundaries while BNA files range 1KB to 50MB depending on boundary complexity
• •TOPOJSON is optimized for web choropleth maps, data visualization, boundary simplification while BNA is designed for atlas gis boundary exchange, regional mapping, legacy spatial data conversion — choose based on your specific workflow needs

Advantages of TOPOJSON

• ✓At its core, TOPOJSON relies on lossy encoding — a design choice that makes it perfect for Web choropleth maps, data visualization, boundary simplification.
• ✓You won't run into compatibility issues with TOPOJSON — it's a universal standard across platforms.
• ✓File size management with TOPOJSON: aggressive compression with minimal visible quality loss.
• ✓Every major application in the Web choropleth maps, data visualization, boundary simplification space supports TOPOJSON natively.

Advantages of BNA

• ✓BNA applies lossy compression specifically calibrated for Atlas GIS boundary exchange, regional mapping, legacy spatial data conversion.
• ✓BNA enjoys broad native support across operating systems, browsers, and creative tools alike.
• ✓BNA delivers impressive compression ratios, shrinking files dramatically while keeping visual quality high.
• ✓You will find BNA support built into virtually every tool that handles Atlas GIS boundary exchange, regional mapping, legacy spatial data conversion — no plugins or converters needed.

Common Use Cases for TOPOJSON to BNA Conversion

Industry Applications

Best Practices for TOPOJSON to BNA Conversion

• →When converting TOPOJSON to BNA: confirm the coordinate reference system (CRS / projection) is preserved or explicitly reprojected
• →Keep attribute tables and feature metadata intact — BNA should retain all fields from TOPOJSON
• →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 TOPOJSON to BNA Conversion

• !BNA features land in the wrong place after TOPOJSON to BNA → verify the CRS/projection; mismatched coordinate systems shift geometry
• !Attribute columns missing in BNA → some GIS formats have field name length or type limits; rename or cast columns first
• !TOPOJSON to BNA drops the z/elevation dimension → pick a target format that supports 3D geometry
• !BNA 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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