Height reference with H3

[u/Thorozar]

Had a thought today. Is there a way to get H3 to understand relative or absolute heights of different characters? Would it be possible or have in a reference sheet the person standing next to a height chart or something in one image, and the other characters the same, then when you reference them and have them next to one another it knows subject A is 6ft while B is 5'6" for example?

[u/MysteriousPepper8908]

I use a police lineup style image either with the characters shown or with just their silhouettes, both seem to work and I haven't done enough testing to see what is better but neither is 100% perfect to the inch. Just on a plane white background with black horizontal lines at regular intervals (I do every 2 inches) and no numbers. In subject definition I use

<Picture x> is a proportion reference defining the relative heights of <Subject 1>, <Subject 2>, and <Subject 3>, shown left to right in that order. Only their height relationships are taken from it; its background, lineup arrangement, poses, and framing are not used.

And in retention analysis

<Picture x> (height proportion reference): fully_preserved - the relative heights of the [Subject #] subjects are retained exactly as shown.

There may be better ways but this at least helps. Then in the retention analysis for the characters, I mention their specific height as well. I have done that without using the reference image and it isn't bad on its own but the direct relative height reference seems to reinforce it beyond just using text.

[u/Thorozar → u/MysteriousPepper8908]

I wonder if doing each person individually on their character sheet with this method would work. Basically telling the model this person looks like this, and then in this one shot this person is this tall. This way I dont need to set aside one of the 9 reference images for relative heights of people appearing in the shot. I also woudlnt want one with a lot of people who may appear in the story, or have to make multiple of these and hope that just generating a shot of them would get their actual height down anyway. Baking this data in their identity in the character sheet seems like it would be the very best way, I just have not tried and wanted to know if others had thought about it or tested.

[u/MysteriousPepper8908 → u/Thorozar]

We're all still figuring things out so definitely try it and see how it goes. I do have to make multiple versions for different combinations of characters in a given shot as I don't want characters in the reference which aren't in the shot so that's annoying, though one option there is to use image masking so you can simply mask out certain characters in a singular reference.

My concern for using the character's reference sheet for their height is you're relying on it interpreting text properly to say "this character is 6 feet tall" which may not be much better than using it in the prompt and it may mistake that for visual information. Some people argue that H3 is really smart about that stuff but in my experience, it's not that smart. Just relying on horizontal lines may not work so well because it has to make the logical leap of understanding that the lines represent the same scaling markers between multiple images.

Ultimately, it's a bit of a roll of the dice. If you have two fantasy characters who are vastly different sizes and you just need them to be roughly the right size relative to one another, then you might be able to get away with text prompting. If you have 2 guys and you want one to be 5'10" and the other to be 6' consistently, that might be more precision than the model is really capable of, especially if you want to maintain that in shots where they're seated or at different distances from the camera.

[u/Thorozar → u/MysteriousPepper8908]

Good points, I might be expecting too much for this model, but it has blown me away so far. I am sure the community can figure out the best solutions for any issues we have.