Gaia comes with a Scanner that allows you to create your own stamps.
The scanner can convert the following types of things into stamps:
- Grey scale images
- RAW files
- 3D models (as long as they have a collider on them)
- World Machine w16 terrain export files
There is a great site called Terrain Party that allows you to get real world locations in the form of a high resolution .png image file which can then be imported into Gaia.
To learn how to import and convert these to stamps check out the following tutorial: