How to do face detection in digiKam and import them into IMatch?

[ChicagoGhost]

I tried face detection in IMatch with 1000~2000 photos. Many faces are not detected, especially for photos with many people, in which the faces are small. Adding face annotations to them one by one is really a tedious job. And there are 150K photos waiting for me to do this.
Using the YOLO v3 model in digiKam, a higher percentage of the faces can be detected, saving me a lot of work.

So I would like to use the face detection function in digiKam and then import them into IMatch.

First, is this a good idea? I don't know whether digiKam will mess up IMatch's photo directory, or mess up the metadata IMatch has written to the photos.

Second, I can't make it work. In digiKam, I have checked "Face Tags" in settings-metadata-behavior. I have run the command from menu: Album-Write metadata to files. In IMatch, I can't see the face annotations. I used the command-Add or update folders. I even created a new database from those photos.

[mastodon]

Check whether Digikam saves the face tags in the jpg file. If it does not, just in its database, IMatch can't read it.