Jugofthat said:
Viewing angles, and character visibility within the frame (half-length, 3/4 length etc).
Admittedly, both tag families tend to only lend themselves to solo pics, but even then they're usually omited.
Front_view especially.
The issue with half-length_portrait, three-quarter_portrait, etc., besides being a pain to type in, is they imply portrait which is a particular type of image. Many images only showing part of a character are not portraits and there are no non-portrait equivalents to those tags as far as I know. For example:
About 3/4 of him is shown but it's not a portrait, so we can't tag it as three-quarter_portrait.
Updated by anonymous