...

$ sudo su
$ cd /opt/sufia-project/current
$ bundle exec rails c production

irb(main) > file_set = FileSet.find("z029p569t")
irb(main) > file_set_id = file_set.files[0].id
irb(main) > CHF::CreateDerivativesOnS3Service.new(file_set, file_set_id).call

Creating, cropping, uploading collection thumbnails

Instructions for doing this are on github .