E57 is an open-source 3D imaging data format designed for storing point clouds, images, and metadata from laser scanners and other 3D measurement devices.

E57 Format

Overview

The E57 format is an open, vendor-neutral file format developed by the American Society for Testing and Materials (ASTM) and maintained by the 3D Imaging Systems Association (3DISA). It serves as a comprehensive standard for storing three-dimensional imaging data, particularly point clouds captured by terrestrial laser scanners (TLS), mobile laser scanning (MLS) systems, and other 3D measurement devices used in surveying and documentation.

History and Development

The E57 format was officially standardized as ASTM E2807 and published in 2011. Its development was driven by the need for an efficient, standardized method to exchange 3D imaging data across different software platforms and hardware manufacturers. The format specification continues to evolve, with improvements addressing data compression, expanded metadata support, and enhanced interoperability.

Technical Characteristics

E57 files utilize an HDF5 (Hierarchical Data Format 5) underlying structure, providing a robust and hierarchical organization of data. This foundation enables efficient storage and retrieval of large point cloud datasets. The format supports flexible data organization, allowing users to store multiple point clouds, associated images, and comprehensive metadata within a single file.

The format includes native support for binary data storage, which significantly reduces file size compared to text-based formats like ASCII or XYZ. Typical E57 files compress 3D point data with associated attributes such as intensity values, RGB color information, and normals, making it ideal for large-scale survey projects.

Key Features

Point Cloud Storage: E57 efficiently stores millions of points with spatial coordinates and associated properties. The format accommodates intensity data from laser returns, essential for reflectance-based analysis.

Image Integration: The format enables storage of high-resolution images captured alongside point cloud data, facilitating visual documentation and texture mapping applications.

Metadata Support: E57 includes comprehensive metadata sections for recording instrument information, scan parameters, coordinate system definitions, and quality metrics.

Scalability: The hierarchical structure supports multiple scan datasets within one file, enabling organized storage of complex survey projects.

Applications in Surveying

E57 has become an industry standard for:

Heritage Documentation: Recording architectural and archaeological sites with high geometric precision

Construction Monitoring: Tracking structural changes during building projects

Infrastructure Inspection: Assessing bridges, tunnels, and other critical infrastructure

Facility Management: Creating as-built models and spatial databases

Deformation Analysis: Documenting changes over time through multi-epoch scans

Advantages

The open-source nature ensures broad software compatibility across surveying, CAD, and GIS platforms. Efficient compression reduces storage requirements without quality loss. The standardized format eliminates vendor lock-in and facilitates long-term data archival and interoperability.

Limitations and Considerations

While widely supported, some legacy surveying software may require additional plugins or conversion tools. The binary format, while efficient, is less human-readable than text-based alternatives, requiring specialized viewers for inspection.

Conclusion

The E57 format represents a significant advancement in 3D data standardization for the surveying profession. Its adoption as an ASTM standard, combined with broad industry support, makes it the preferred choice for organizations requiring reliable, future-proof point cloud storage and exchange.

e57 format