Maybe, his later film pic related had a mix of 2D/3D.
Director Jean-François Laguionie mentioned in http://www.zewebanim.com/laguionie.htm
that they did detailed storyboards and had a studio in Asia (Studio Paek-ho) do the animation, taking two years. From the IMDB crew list: model sheets by Guy Delisle.
Translated excerpt (he did rough sketches for the whole story and filmed them with a video camera first):
AH: Are you already directive in these sketches?
JFL: No. Camera movements, I do not see them very much. I know that in such a plan, I am in broad terms; it is possible that I follow this character in tracking shot before moving to the fixed shot. But I do not care about that. What matters to me is what I want to tell, my first problems of cinema are rather in the chain of the story. After, the camera will link things together. Once I finish all these sketches, I film them with a small video camera. At this stage I feel completely free. After, the problems will accumulate: it will have to think of a whole lot of technical questions. But for the moment everything is created, so it is extremely enjoyable; I feel like a kid. So I film all this with a holiday video camera, then, I assemble everything with a software for editing holiday movies. So it's very limited, but that's enough. Then to give a little flame, breath, I add music, then I start to work the dialogue by making all the voices myself. This is a step that I think is important and I'm sure many directors do this today because it allows to quickly check a number of key issues, rework dialogues, check the general pace ... because even if the drawings are fixed, their succession allows to give the rhythm of the film, to check the dramatic situations ... The character of the characters is already drawing, even if the drawings are coarse, we begin to see after three-hundred and fifty drawings if the character has small eyes or big eyes, if it is small, big, etc ...