Well, it's not at all obvious that a line is the naive representation of a limb rather than a particularly intelligent encoding of it. For example: CNNs, thoug

Well, it's not at all obvious that a line is the naive representation of a limb rather than a particularly intelligent encoding of it. For example: CNNs, though pretty good at detecting limbs (and miscellaneous other things) have only a very limited ability to encode structural information in this way. An interesting open question in the field is what is the "right way" to encode this sparse, graph-like structural data (hence capsule networks).