- Select and object that uses your emissive material.
- In the details panel of your object search 'static' to find the lighting settings of your object.
- Check the 'Use Emissive for Static Lighting' box.
- Tweak the emissive boost to make the emitted light travel more. The emissive boost needs to be higher for larger objects.
- Use the static lighting scale slider in the World Settings panel to make your build times quicker.
- Build the lighting of your level and check out how the emissive has affected the geometry around it - tweak the emissive value and the emissive boost and rebuild to get different effects.
- Use Show - Visualise - Volumetric lightmap to see a visualiser of where your light is travelling to in the viewport.