How to design a coherent character with NovelAI?
First, always keep in mind what an AI is good at: making art of what it really knows. The training material for the AI consisted of a huge number of anime/manga drawings. What will it know well then? Everything that is frequent in anime and manga: girls, girls, girls, beautiful scenery, boys, city life, cats, dogs, Japanese temples... What did it not see often? Ugly scenery, horses, cows, old telephones, exotic places... In other words, you can expect to get pretty pictures of girls easily, but cows... Well, be happy if they have four legs!
With this in mind, plan your visuals. This will limit your creativity a bit, but then again, you will be rewarded with beautiful pictures!
Now, how to start the image production for character design:
First, you need to collect the right tags for your character. There is a great table for this online that you can take as a starting point. There is also danbooru.donmai.us, but be warned that this is not suitable for underaged and might cause nightmares... (There are innocent sample pics mixed up with some very bad adult content, sometimes of questionable legality, so better stick to the spreadshirt linked above.)
You should use as many tags as possible to be very precise, but do not use too rare tags either: remember, the AI is only expert on what it knows well!
Here is a sample for such tags that I have used for one of the characters:
feet out of frame,mature male, tall, standing, short hair, purple hair, tan,tsurime,brown eyes,constricted pupils, rectangular eyewear, black-framed eyewear,white shirt,collared shirt,short sleeves,black pants, toned male, facing viewer, transparent background,angry
You will probably not know what is "tsurime" – it's a certain eye shape, but Google is your friend on such terms (for me also for haircuts, because, you know I have short hair, that's easy then...) "Feet out of frame" is important as it produces the right size for a visual novel. For girls, by the way, you can choose even more tags, as the AI knows better how to paint them. Be very specific there!
Do not add tags like "earrings" or "amulet": such details will look very different every time the AI draws it. Better let the AI draw it once and then copy paste it later with Procreate.
Add face expressions towards the end ("smile", "angry" etc.). That way changing them won't change the overall look of the person too much.
Next step is that you generate a pic in the desired size (portrait medium is good enough for my resolution) with a low number of steps (I use 22). Scale is not as relevant. Happy with the result (more or less at least)? Great! If not: Redo it with a different seed. (If you leave it blank, NovelAI fills in a different one for you every time anyway.) If you are happy, check that the perspective is good: often the view will be from above or below. That's useless for a VN, even if it looks gorgeous, believe me! Also, often you will get more than one person in the pic. Just ignore those as well.
Once you are happy, fix the seed. You now might have to increase the steps. That can help to cure bugs, like hands with six fingers, three armed-creatures etc. It can also make the picture look more awesome. (The higher, the more expensive. The maximum seed is 50.)
Then try now to modify the face expressions. Every time save the pictures. You probably also need to change arm positions or other things to get different postures for variety. Once you have like four good postures with more or less consistent clothing, hair style etc., you can move over to Procreate (or your favourite drawing software). First, you will need to remove the backgrounds here. You will have to do a lot of manual work there, unfortunately. It's actually the most time consuming part. There are AI softwares for this task, but my trials there were mixed, so I decided against spending money on that and rather did it by myself manually.
Other issues that need to be fixed manually: hands, differences in the clothing (collars and sleeves that change colours, e.g.). Often copy paste is helpful for fixing these issues. Also use copy paste to give your postures different face expressions. I usually produce around 10 different expressions per character, typically: neutral, happy, smiling, laughing, sad, angry, surprised, shy, and a few more, depending on the character (see picture). Some face expressions have to be adjusted manually, but that's not so difficult.
So, finally, you have your own original character set up for your VN! – But you are not done yet: you need to come back for making CGs and also different outfits... So make sure to save all data, including the scale and seed you used! Also, when in the above-mentioned process some nice, but unusable pictures (e.g., wrong perspective or clothing) come up: save them for the CGs!
That's all for now: Happy character design! :)
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