That is a type of trapunto. I enlarged the picture and you can see where the quilted areas were filled with batting to make them stand out. Or it was quilted over an extra layer of batting and the excess was trimmed away...but that would be hard to do in those little triangle areas.
That is a stunning quilt, I can see why your are intrigued with it :D:D:D
Edit****
I don't think I was right... It looks like the quilt center is laying flat and it is the optical illusion... Was it flat or raised K?