Interfacing to New Simulators

To interface Scenic to a new simulator, there are two steps: using the Scenic API to compile scenarios and generate scenes, and writing a Scenic library defining the virtual world provided by the simulator.

Using the Scenic API

Compiling a Scenic scenario is easy: just call the scenic.scenarioFromFile function with the path to a Scenic file (there’s also a variant scenic.scenarioFromString which works on strings). This returns a Scenario object representing the scenario; to sample a scene from it, call its generate method. Scenes are represented by Scene objects, from which you can extract the objects and their properties as well as the values of the global parameters (see the Scene documentation for details).

Supporting dynamic scenarios requires additionally implementing a subclass of Simulator which communicates periodically with your simulator to implement the actions taken by dynamic agents and read back the state of the simulation. See the scenic.simulators.carla.simulator and scenic.simulators.lgsvl.simulator modules for examples.

Defining a World Model

To make writing scenarios for your simulator easier, you should write a Scenic library specifying all the relevant information about the simulated world. This “world model” could include:

  • Scenic classes (subclasses of Object) corresponding to types of objects in the simulator;

  • instances of Region corresponding to locations of interest (e.g. one for each road);

  • a Workspace specifying legal locations for objects (and optionally providing methods for schematically rendering scenes);

  • a set of actions (subclasses of Action) which can be taken by dynamic agents during simulations;

  • any other information or utility functions that might be useful in scenarios.

Then any Scenic programs for your simulator can import this world model and make use of the information within.

Each of the simulators natively supported by Scenic has a corresponding model.scenic file containing its world model. See the Supported Simulators page for links to the module under scenic.simulators for each simulator, where the world model can be found. The scenic.simulators.webots.mars model is particularly simple and would be a good place to start.