ERS / ERMapper Raster
Aug 27,2026

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Introduction

ERMapper Raster (abbreviated as ERS) is a proprietary raster data format of the ER Mapper remote sensing software under Hexagon Geospatial. It consists of a text-format .ers header file (storing image attributes, metadata, and georeferencing information) and a raw image data file with no extension. It supports multi-band storage, can carry various raster data types such as photographic imagery and terrain elevation, automatically includes coordinate system information, and accommodates multiple numeric data types including 8-bit, 16-bit, and 32-bit. It is widely used in GIS-related fields such as remote sensing and surveying.

File Structure

ERS/ERMapper Raster is the native remote sensing raster storage format of ER Mapper software. It adopts a separate "header file + independent data body" structure overall. The core components are as follows:

Text header file (.ers extension): Stored in plain text format, it completely records the image's metadata, including core attributes such as number of rows and columns, number of bands, data bit depth, projection coordinate system, and georeferencing affine transformation parameters. Basic information can be quickly read without parsing complex binary structures.
Raw image data file: Typically has no custom extension and stores uncompressed pixel values in binary form. It supports multi-band interleaving or band-sequential arrangement, accommodates various numeric types such as 8-bit, 16-bit, and 32-bit, offers high read/write efficiency, and can directly interface with ER Mapper's real-time processing workflows.
Supporting auxiliary associated files: In some cases, related auxiliary files are automatically generated to store color mapping tables, processing algorithm parameters, pyramid indexes, and other extended information, helping the software achieve rapid visualization and subsequent remote sensing processing operations.

Pros

Clear structure and easy parsing: With a design that separates the header file from the raw data, the header file stores metadata such as row/column counts and geographic coordinates in plain text. Basic information can be quickly read without complex decoding, meeting the efficient data interchange needs of professional scenarios such as remote sensing and surveying.
Strong data compatibility: Supports multi-band storage and can carry various raster data types including satellite imagery and digital elevation models. Coordinate system information is automatically included. Most mainstream GIS software can directly recognize and import it, and in some cases, coordinate system assignment can be completed automatically.
Comprehensive data type coverage: Supports 8-bit, 16-bit, and 32-bit unsigned/signed integers as well as 32-bit floating-point data, meeting the storage requirements of remote sensing analysis and numerical computation at different precision levels.
Adapted to professional processing workflows: Deeply integrated with ER Mapper software, it can directly interface with its algorithm-based intermediate-file-free processing workflows, significantly reducing storage space usage for large-scale remote sensing projects and improving batch processing efficiency.

Cons

Relatively closed format: As a proprietary format of ERMapper, support from niche remote sensing tools outside the ER ecosystem is incomplete. Some third-party software can only read basic information and cannot fully write extended attributes such as Nodata values.
Insufficient geospatial information stability: The built-in coordinate system and georeferencing information may have minor deviations. Some files may even lack any coordinate information entirely, making spatial positioning anomalies likely when imported into other platforms.
No built-in compression mechanism: The raw data files are uncompressed, resulting in large file sizes for massive remote sensing imagery. Compared to companion compressed formats such as ECW, data storage and transmission efficiency are lower.
Special attributes are easily lost: The rotation angle attribute supported by the format is often ignored during cross-software reading and writing. In some scenarios, write operations may cause minor data distortion or precision loss.

Application Scenario

As the native raster format of ER Mapper software, ERS/ERMapper Raster is primarily used in professional engineering scenarios related to remote sensing and surveying. Leveraging its full data type support and seamless interoperability with mainstream GIS platforms, it can be used for redundancy-free batch processing of large-scale remote sensing imagery, mosaicking and orthorectification of multi-source aerial and satellite images, as well as supporting image analysis and result output in geological exploration and ecological environmental protection. It is also suitable for pre-processing steps before publishing massive imagery online. It is widely used in large-scale remote sensing projects by surveying, land, and other professional departments in 142 countries worldwide