OpenSCENARIO (.xosc)
Jun 24,2026

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Introduction

OpenSCENARIO (.xosc) is a standardized XML format maintained by the ASAM (Association for Standardization of Automation and Measuring Systems) organization, specifically designed for describing dynamic scenarios in traffic simulation. It focuses on the behavioral interactions of traffic participants such as vehicles and pedestrians, and can reference static road network files such as OpenDRIVE. Through a hierarchical storyboard structure, it defines event trigger conditions and action sequences, serving as the core universal standard for achieving scenario reusability and cross-tool interoperability in the field of autonomous driving virtual testing.

File Structure

The .xosc file of OpenSCENARIO is built on the XML format and adopts a hierarchical structured design. The core components are as follows:

FileHeader: Records the file version number, creation date, scenario description, and author information, used to identify the OpenSCENARIO standard specification the file follows.
ParameterDeclarations: Centrally defines reusable parameter variables within the scenario, supporting direct reference to numerical values via parameter names, facilitating batch modifications and scenario configuration extensions.
Catalog: Stores various reusable scenario element templates, including categorized catalogs for vehicles, pedestrians, maneuvers, trajectories, controllers, and more, significantly enhancing the modularity of scenario development.
RoadNetwork: Describes the static road environment upon which the scenario relies, typically referencing OpenDRIVE-format road network files, while also defining supporting elements such as traffic signal states within the scenario.
Entities: Defines all participating objects within the scenario, including test vehicles, traffic vehicles, pedestrians, static obstacles, and more. Each entity can be associated with type templates defined in the catalog and configured with its own size, performance, and other attributes.
Storyboard: The core part of the file. It first sets the initial states of all entities and the environment through the Init node, then uses the hierarchical structure of "Story-Act-Maneuver-Event-Action," combined with triggers, to define dynamic behaviors under different conditions, fully orchestrating the synchronized interaction logic of multiple participants.

Pros

Standardized cross-platform compatibility: As one of the ASAM OpenX series standards, it serves as the industry-standard language for dynamic scenario description. Scenario files written in this format can be directly reused across different simulation platforms and real-vehicle test tracks without repeated adaptation, completely resolving the "platform lock-in" issue where scenarios are not interoperable between different tools.
Machine-parseable and editable: Built on the mature XML standard, it supports direct validation, import, export, and modification by various simulation tools and scenario editors. Its structured hierarchical design also facilitates batch processing of scenario files in automated testing workflows.
Strong scenario coverage and reusability: Supports the Catalog mechanism to encapsulate reusable vehicle, maneuver, trajectory, and other elements. It also supports parameterized configuration, enabling the batch generation of a large number of derived test cases by simply modifying parameters, efficiently covering complex multi-participant interaction scenarios.
Good ecosystem synergy: Can seamlessly work with other standards in the same series, such as OpenDRIVE (static road network) and OpenCRG (road surface properties). Together, these three standards provide a complete description of both static and dynamic elements in autonomous driving simulation scenarios, making them the industry-recognized cornerstone standard for simulation testing.
Excellent extensibility: The standard reserves flexible extension mechanisms, easily accommodating new types of traffic participants and custom behavioral attributes. Version 2.X further supports abstract scenario descriptions and built-in KPI statistics, adapting to a wider range of testing requirements.

Cons

Insufficient scenario reproduction consistency: The standard only defines the description rules for dynamic behaviors but does not constrain the underlying behavioral model implementation of the simulation engine. The same .xosc file may produce different simulation results when run on different simulators, making it impossible to guarantee completely consistent reproduction.
Limited standard coverage: It is only responsible for describing the dynamic content of scenarios and does not include road networks, vehicle dynamics, system-under-test information, or other elements. It cannot independently constitute a complete simulation test case and must be supplemented with other supporting files to build a complete simulation environment.
Ecosystem adoption not yet fully mature: Some niche simulation tools do not fully support this standard. Additionally, compatibility and precise reproducibility between the parallel 1.X and 2.X versions still have implementation-level differences, and some concepts are not yet fully mature and clearly defined.
Steep learning curve: The native XML format has a complex tag system, making manual authoring of complete scenarios a high learning-cost task. Non-professional users find it difficult to quickly build complex scenarios through plain text alone and must rely on supporting visual scenario editors to improve development efficiency.

Application Scenario

OpenSCENARIO (.xosc) is primarily used in the virtual closed-loop verification of ADAS and autonomous driving functions. Engineers can use it to precisely define various routine scenarios such as highway overtaking and urban intersection interactions, while also efficiently covering extreme edge cases that are difficult to reproduce in real-vehicle testing, such as traffic congestion and sudden pedestrian crossings. With AI-assisted tools, it can also batch-generate massive numbers of test cases. Leveraging its cross-platform compatibility, it enables seamless migration and sharing of scenarios between different simulation tools and real-vehicle test tracks, significantly reducing the repetitive development costs of autonomous driving testing. It also supports related work in intelligent transportation, such as traffic flow model calibration and multi-vehicle cooperative scenario simulation.