A geometric pattern is far harder to upholster than a floral one, and this chair is covered in the hardest kind.
A floral forgives. If a spray sits two millimetres off centre or a stem bends slightly as the cloth goes over a curve, nobody can tell, because the design has no straight lines to measure against.
A lattice has nothing but straight lines. Every diamond is a set of parallels, and the eye reads a parallel line the way it reads a spirit level - instantly, and without being asked. Pull the cloth a fraction unevenly across a domed back and the diamonds stretch on one side and compress on the other, and the whole back looks as though it is leaning.
So a lattice is set from its centre outward. The upholsterer finds the true vertical of the back, marks it on the cloth, aligns one column of diamonds to it, and then works outward in both directions at once - taking equal tension left and right at every stage so the grid stays square as it climbs over the curve.
The seat is then aligned to the back rather than to itself, so that the diamonds appear to continue down from one to the other when you look at the chair from the front.
It takes considerably longer than a plain cover, and it is the reason a lattice looks either extremely good or obviously wrong.