@Hermyth here is the commands: arcoreimg 工具 | ARCore | Google Developers
I manually built an image database file. If your image doesn’t have enough feature points, it will throw an error saying so. If it does, it will work.
Mind I have edited my post above (including a link) that shows you must use a certain source build of Unreal 4.19 provided by Google, which has the arcoreimg tool and ARCore 1.3, opposed to Unreal’s 4.19 and 4.20P5 having no arcoreimgtool and ARCore 1.2. I also tried copying the tool to 4.20P5 and it doesn’t work.
I have learned in the 4.19-ARCore build from Google, you don’t need to use the commands to build a image database manually, but the build will fail if the images aren’t complex enough, and it won’t fail if they are. Hope this helps!