Visual appearance is an important factor in product and lighting design, and depends on the combination of form, materials, context, and lighting. Such design spaces are seemingly endless and full of optical as well as perceptual interactions. A systematic approach to navigate this space and to predict the resulting appearance can support designers in their iterative work flow, avoiding losing time on trial and error and offering understanding of the optical and perceptual effects. It should also allow artistic freedom to interactively vary the design, and enable easy communication to team members and clients. I will present examples of such approaches via canonical sets, simplifying design spaces in perception-based manners to arrive at intuitive presentations, with a focus on light(ing) design and material appearance.