For the design of unmanned aircraft systems, rendering mainly includes the rendering of the UAV itself, and the ground facilities.
After the 3D modeling process in industrial modeling software, you can export the model to software that have easy rendering tools like Blender which can use Blender kit to apply materials, backgrounds, etc.
Rendering of UAVs
You can design patterns of the livery first on graphic software like Procreate and export them in image format to attach them on the curved surfaces (fuselage, vertical tail, etc.) of UAVs.
Here’s an example:
Rendering of ground facilities
This can be complicated if there are many parts. Usually, the rendering of ground facilities includes: selecting the materials of architectures, background attachment, light adjustment, etc.
Take this as an example:
UAV Design Training 