A uniform structure is identified by each sphere having the same number of contacting neighbours. This gives each sphere an identical neighbourhood. In the example image on the side each sphere has six neighbouring contacts.
The number of contacts is best visualised in the rolled-out contact network. It is created by rolling out the contact network into a plane of height  and azimuthal angle  of each sphere. For a uniform structure such as the one in the example image, this leads to a regular hexagonal lattice. Each dot in this pattern represents a sphere of the packing and each line a contact between adjacent spheres.
For all uniform structures above a diameter ratio of , the regular hexagonal lattice is its characterising feature since this lattice type has the maximum number of contacts. For different uniform structures  the rolled-out contact pattern only varies by a rotation in the  plane. Each uniform structure is thus distinguished by its periodicity vector , which is defined by the phyllotactic triplet .