Start with an application reference
The IKEA México Samsala example shows a broad rib on a finished sofa. If specifying a directional warp-knit velvet, lay two pieces from the actual quote beside each other and rotate one. Record how much the visual shade changes.
Carry the decision into the cutting room
Draw arrows on the seat, back and arm patterns. Ask the workshop to confirm fabric consumption with one-way cutting. Sew the most visible join before approving the roll.