The focal point editor in the asset manager works by setting the “fp.x” and fp.y" fields, that seems to work great. The only thing I haven’t been able to figure out is what type of coordinates they output. Other focal point coordinates I’ve seen before were either percentage based, or a version of px that could be used in conjunction with object-position. What is the intended use for the focal point field?
Its percentage based, you can check that when including an asset in your collection and seeing the resulting json, the asset fp value will be between 0 and 1.
as @pauloamgomes said it is percentage based. it is used by the image api when generating thumbnails, so the focal point is always visible.