Unity3D Usage_Guide
The Unity3D environment asset bundle can be downloaded from here (9.4GB download).
To import the environmental assets in the Unity3D editor, we recommend creating a new High Definition Render Pipeline project with Unity3D version 2018.3.14f1 using the "Creating an HDRP Project" section of this Unity3D guide. Once the project has been created, you can import the environment assets by dragging the .unitypackage file into the editor.
In addition to the steps above, clone the FlightGoggles renderer source code into the your_project/Assets folder in your newly created project. Then copy your_project/Assets/FlightGogglesRenderer/ProjectSettings to your_project/ProjectSettings.
To run the FlightGoggles simulator, navigate to your_project/Assets/FlightGogglesRenderer/FlightGoggles/Scenes/Top_Level_Scene.unity before pressing "Play" in the Unity3D editor. Make sure that the resolution settings in the upper-left corner of the game-window match the camera resolution settings defined in ROS.
Once FlightGoggles is running in the Unity3D editor, you can follow the directions for external_renderers in the main FlightGoggles ROS documentation