LAST UPDATED: 16 November 2021

FIRST RELEASE: v0.9

The observer is a pawn in the Unreal Engine that can be moved around by the user in run-time. It displays the world from a unique viewport and can act as a window to the simulation. All levels will have a pawn, regardless if the Nominal pawn is being used or not. We recommend making use of the Nominal Observer pawn that we have built for each of the scenes, as it is fully functional with the Universe system and provides some useful functions that can be used within the simulation. Additionally, the observer is able to track different spacecraft and other objects in the simulation.

Spawning the Observer

The observer must be added to each of the level blueprints. The current functionality requires that the observer to be added after all spacecraft have been added to the level. This is because any spacecraft that require tracking must already be spawned into the scene before the pawn is spawned into the scene. This requirement may be removed in the future. Any spacecraft spawned after the observer will not be able to be tracked.

To spawn the observer, use the Spawn Actor node in the level blueprint, and select the Nom_Observer class. This class can be found in the BskPlugin Content folder, under Observer.

The *Nom_Observer *****class uses the *BskObserver *****class, but has some additional functions that are not found in the base class (such as spacecraft line tracking). Make sure to select this one. In the spawn transform, right click and select Split Struct Pin. This will open up the spawn transform location, rotation and scale. Keep all of these values as default. Even if you want to set the observer to a different location, it will not change the starting location by altering these variables.

There are a few spawn parameters that can be adjusted here:

• Base Movement Speed: This is the movement speed in m/s that the observer can move around the world when it is not currently tracking any objects. By default, this value is set to 2,000 kilometres per second and can be adjusted here. Additionally, the speed can be adjusted by the controls, seen in the section below.
• Base Target Movement Speed: This is the movement speed in m/s that the observer can move around the world when it is currently tracking a spacecraft. This will be relative to the spacecraft, as the observer will continue to follow the spacecraft as it moves around a planet or simulation. This can also be adjusted by the controls.
• Distance from Target: This is the distance to spawn the observer away from the target in m when the simulation starts. Every time the observer tracks a new object, it will be located this distance away in real units from the object.