Understanding 3D Tileset Compression and Decompression
Depending on what you expect to do with the 3D Tiles produced by BrightEarthOnDemand you may need compressed or uncompressed files; lets see why.
Overview
When downloading 3D tilesets from our BrightEartOnDemand platform, users receive compressed files to optimize performance. These files, typically in .json and .glb formats, are compressed using the Gzip compression. This compression significantly improves data transfer efficiency when serving tiles from a web server. However, for direct use in certain client applications—such as Cesium for Unreal, ArcGIS, and Terra Explorer—these files must be decompressed.
Why Compression is Used
Gzip compression is widely employed to:
- Reduce file size for faster downloads.
- Optimize bandwidth usage.
- Improve load times when tilesets are served via a web server.
Web servers can automatically handle Gzip-compressed files, serving them efficiently without requiring additional decompression by the client.
Query and Response Headers for Gzip Compression
When requesting Gzip-compressed files from a web server, the client typically includes the Accept-Encoding header in the HTTP request to indicate support for compressed responses:
Accept-Encoding: gzip, deflate
On the server side, if Gzip compression is enabled, the response will include the Content-Encoding header to indicate that the returned file is compressed:
Content-Encoding: gzip
Additionally, the Content-Type header specifies the type of file being served, such as JSON or glTF:
Content-Type: application/json
These headers ensure that clients and web servers efficiently handle Gzip-compressed files, reducing bandwidth usage and improving load times. However, many 3D applications expect raw .json and .glb files, necessitating manual decompression after download.
Automatic Decompression with BEOD Downloader
To simplify the process, our BEOD Downloader application provides an option to automatically decompress 3D tiles files during download. Users can enable this feature by selecting the 'Uncompress' checkbox within the application. This eliminates the need for manual extraction, ensuring that the files are immediately ready for use in Cesium for Unreal, ArcGIS, Terra Explorer, and other compatible applications.
Conclusion
Using Gzip compression ensures efficient file delivery, but some applications require decompressed files for direct use. The BEOD Downloader’s built-in decompression feature streamlines this process, making it easier for users to access and utilize their 3D tilesets without additional steps. If you encounter issues, ensure that your decompressed files are properly formatted and compatible with the target application.
Choosing Between Compressed and Uncompressed 3D Tiles
If you intend to use the 3D tiles locally, downloading the uncompressed version is likely the best choice, as it avoids the need for manual decompression. However, if you plan to serve the tileset from your own web server or upload it to Cesium ION, the compressed version is recommended, as it optimizes file transfer and server performance.