He says as a result of those base movements, the following nine classes of folds can occur (in all kinds of complicated combinations): stretching-folds, bending-folds, cross-folds, pressure-folds, fragmented-folds, hanging-folds, enclosed-folds, flight-folds (in wind and water) and passive-folds.
So, when doing folds, even in a still image, it is always necessary to think about motion and force for without those, there would be no folds. On earth, one force is always present and that's gravity. So as I do my folds, I constantly aim to keep thinking about how gravity tries to pull down every point (pixel) across the whole surface and whether it is allowed to fall or whether is is blocked either by something underneath or because of being attached to a part of fabric from which it hangs. That way, at least passive- and hanging-folds basically create themselves for as long as I manage to stay focused. Interruptions seem to destroy the mental model of gravity and fabric-thinking-mode so it always takes a bit of time to get back into it after a break.
Thank you for sharing this dennis! I've always felt my way trough folds, and I dont have the language for all of those different conditions, so I probably stand to learn a lot from someone who can explain it in such a detailed way.
You are really bringing a lot into the table by not only listening to advice but going out of your way to learn MORE than what you're being told AND most importantly then share back with us what you learnt =D
I think I'm gonna look up Hogart too! He's got a whole book on folds, so I imagine you're reading another book with only one chapter on folds, right? please share which one =)
on your newest revision: that looks like a very detailed fold map! I think it shows that you've got a lot going on in your head, you're obviously learning a lot =). one thing that I would change about the way you're doing folds though, is that sometimes when two folds meet they dont add up, instead they erease eachother, sometimes with the weaker fold surviving but a little twisted by the other one's force...I think you might see some of that in your ref if you look for it.
in general this version looks like a fold map, which I'm sure willl be very useful for learning, but when you're done with it you should think of how the light hits things and which folds would be hidden by either too much light or too much shadow and try to erease some of them away. Not only for being realistic with the lighting but for a design reason, because as it is the fold map would be too busy for a finalized sprite, specially because you've got a very hi-contrast image here with only those two shades. Dont worry about that yet though, I think assimilating all this information is good work so do what you have to do. You could also add more shades later so that the information is still there but isnt as overwhelmingly contrasted.
EDIT: made an edit BEFORE I may get too busy :p

I went and contrasted up your refs, to something that still shows all the detail but is close to the level of contrast of your sprite.

I went and did the lighting thing on it. Mostly you had good folds going on, but I think the lack of contrast in your ref made some of the folds too regular, specially the big ones in the middle of the first frame. you might notice I removed a lot of the folds at the botton, it's ok to not show the whole line for the fold, just the corners, specially if it's in a dark shadow or really bright light
Also, I went and looked up the folds guy. His drawings seem from a universe where every fold that could possibly ever happen, does. Makes a lot of sense that he did a whole book on how to make them, because his illustrations might be famous for them, but his folds are more abundant than in reality, it's not even in the levels of roman or greek statues, it's closer to 90's comics fold crazyness. I removed a lot of weird insinuations of folds you had on the tighs, I think you were trying to communicate the crumpled fabric but it kinda looked like a glitch or something.
So, I think you might be getting a bit too many folds from trying to think like him, keep his principles in mind if they're good for you but with a grain of salt and compare to your refference, you should deffo not have more folds than your refference, specially because you're animating and specially because you only got 2 shades.
Finally, I think you're still shortening the robe waaay too much. Do you have a thing for wizard knees? :p Remember those vertical folds mean that there's a lot of excess fabric there that will get stretched when he stretches his legs sideways, so instead of pulling the robe upwards the leg will just get the excess fabric from the vertical folds. I only did it up until he lifts his leg cause it gets the point across :p