I want to do some kind of 360 degree tour.
I understand that I have to use a spheregeometry.
But in some cases I don’t have the full equirectangle image but just like a 30 ° x60 ° part.
And no idea how to do this.
Depending on how your images look and how they are connected (sounds like a cubemap to me tbh, unless you mean it’s just a 360 panorama cut in several parts?) you can:
(1) Join them in Photoshop and save yourself 100 hours of trying to automate it in js / three.
(2) If 1 is not possible, you can try using PMREMGenerator.fromEquirectangular or PMREMGenerator.fromCubemap.
(3) If that still does not work, you can create a CanvasTexture and glue all the parts together to form a 360deg map - then return to point 2.