Surface geometry can play an important role in our ability to understand and interpret material appearance and properties. This property ranges from large-scale shape changes impacting our identification of reflections to visible surface roughness affecting gloss perception. In this work, the authors present a user study that examines numerous surface geometries that are defined at the mesoscale: small enough to be considered indicative of the material and not object geometry, but large enough to be visible from a distance with the naked eye. Models of perceived brightness were compared against sparsely collected brightness judgments from the study and used to densely compare many generated mesoscale surface patterns. Averaging incoming luminance over a spatially varying surface proved effective at modeling brightness judgments. The effects of the mesoscale structure on perceived brightness were not directly correlated to parameters such as shape, size, or depth of the bumpy texture elements.