ASAM OpenCRG defines a file format for the description of road surfaces. It was originally developed to store high-precision elevation data from road surface scans. The primary use for this data is in tire, vibration or driving simulation. Precise elevation data allows realistic endurance simulation of vehicle components or the entire vehicle. For driving simulators, it allows a realistic 3D-rendering of the road surface. The file format can also be used for other types of road surface properties, e.g. for the friction coefficient or grey values.  

The standard describes a method to store the data in a specific layout, called "curved regular grid" (abr. CRG). The advantages of this method are high memory efficiency, low computation time for file generation and data processing in simulation tools, and high accuracy of positioning the data onto road networks.

The basic principle for describing the road surface is to place the data into a grid along a road reference line. Line segments are described by a start position and heading angle. The grid is produced by longitudinal cuts (columns) and lateral cuts (rows) along consecutive line segments. Each cell in this grid has a value, typically the elevation. The road center line also includes the end position, which can be used to detect and correct a potential drift of the placement of the data on roads.

ASAM OpenCRG defines ASCII and binary file formats with clear-text headers. The header contains road parameters for the reference line and the overall configuration of the longitudinal sections, a definition of the data format (ASCII and binary), the sequence of data which is expected in the trailing data block, and modifier and option parameters. Furthermore, OpenCRG-files may contain references to other files (typically containing the actual data) to handle different parameters for the same data set.

Data from ASAM OpenCRG can be included in OpenDRIVE road network descriptions. The dynamic content of driving simulations, such as vehicle maneuvers, can be described with ASAM OpenSCENARIO. The three standards complement each other and cover the static and dynamic content of in-the-loop vehicle simulation applications.

The standard is delivered with software libraries in ANSI-C and MATLAB. The libraries for both languages contain functions for reading CRG files, and for modifying and evaluating the imported data. In addition to that, the MATLAB library contains functions to generate, analyze and visualize the data.


Audi AG, BMW AG, Daimler AG, Porsche AG, VIRES Simulationstechnologie GmbH, Volkswagen AG.


OpenCRG v1.1.2

(The link refers to a download page of VIRES Simulationstechnologie GmbH. ASAM bears no responsibility for the accuracy, legality or content of the external site and its downloads.)

Next Steps

Road map to further develop ASAM OpenCRG

The participants of the Proposal Workshop ASAM OpenDRIVE and ASAM OpenCRG (Jan 15 - 16, 2019) decided to propose one project to adapt the current version of OpenCRG to ASAM requirements (Transfer Project) while additionally implementing a few new features (Further Development Project). The aim is to finish the project quickly. More complex developments should be addressed in a separate project. 


Currently the project proposal is written. After publication of the proposal, all members are invited to sign up for participation in the work group. (To be informed about new proposals subscribe to our newsletter)

Related New Standard Developments 

Feb 21, 2020

ASAM OSI Kick-off Workshop

The Open Simulation Interface (OSI) is a generic interface that allows users to connect any sensor with a standardized interface to any automated driving function or driving simulator tool. Join this workshop to bring in your ideas and requirements on how to further develop ASAM OSI. This new standard will be further developed with agile, open source software development methods.

Read more

Mar 03, 2020

ASAM OpenLABEL Proposal Workshop

OpenLABEL aims to introduce a standardized set of labels for objects of interest and for driving scenarios. In parallel it will define a generic labeling format applicable to data not specific to the two aforementioned use cases.
In this workshop the technical content will be defined.

Read more

Past Events: 

Jan 15 - 16, 2019

Proposal Workshop ASAM OpenDRIVE + ASAM OpenCRG


Oct 09 - 10, 2018

Kick-off Workshop ASAM OpenDRIVE + ASAM OpenCRG


Past Events (Proceedings)

Project Status

Project Ongoing

ASAM OpenCRG Transfer and Further Development Project


Call for Offers

This project group is currently seeking a technical writer and/or software developer for support. Submit your offer by Mar 09, 2020.   Read more

Read more




After publication of the project proposal(s), members and non-members have the opportunity to review and comment the proposals and to enroll in the project group(s). Participation in a project group requires ASAM membership.

Ongoing projects on ASAM OpenCRG

Stay informed about the standard development progress, major activities, and new releases:

Subscribe to our newsletter

Open Curved Regular Grid
Application Areas
  • Description of road surfaces
  • Endurance simulation
  • Driving simulation
  • Traffic simulation
Specification Content
  • File format specification
  • C API description
  • MATLAB API description
File Formats
  • crg
Current Version
Release Date
17 Apr 2018
This version of OpenCRG is developed, owned and published by VIRES Simulationstechnologie GmbH. The specification is cur-rently transferred to ASAM to become a public standard. We ex-pect the first release at ASAM in 2019.
Our newsletter informs you when a new standard version is released.