.E57

Introduction

E57 is a vendor-neutral format for data from 3D imaging systems such as terrestrial laser scanners, published by the ASTM E57 committee as standard E2807 in 2011. One file can hold several scans, each with its points, its position and orientation, and the photographs taken by the scanner’s camera.

Scanner makers each have their own formats, so E57 is the common way to move scans between them and into survey, BIM and reality capture software.

Structure

An E57 file is binary with an XML section. It starts with a 48-byte header: the signature ASTM-E57, the major and minor version, the file’s length, the position and length of the XML section, and the page size, which is 1,024 bytes. The whole file is divided into pages of that size, each ending in a 4-byte CRC-32C checksum, so a reader can detect damage anywhere in the file.

The XML section describes the contents: a data3D list of scans and an images2D list of pictures, each with its pose and settings. The point records themselves are stored in compressed binary vectors elsewhere in the file, which the XML points to.

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