VISUALIZING THE APPEARANCE OF AT LEAST TWO MATERIALS IN A HETEROGENEOUS MEASUREMENT ENVIRONMENT

First and second sets of appearance attributes are obtained. The first set is associated with a target material. It comprises measured appearance attributes (54) of the target material. The second set is associated with a candidate material. It comprises candidate appearance attributes that are based on appearance attributes associated with one or more reference materials. A geometric model of at least one virtual object (72) is obtained, the geometric model defining a three-dimensional surface geometry. A scene comprising the at least one virtual object (72) is visualized. First and second portions of the virtual object (72) are visualized using the first and second sets of appearance attributes, respectively. Each of the first and second sets of appearance attributes comprises texture attributes in the form of a plurality of sets of image data, each set of image data associated with a different combination of illumination and viewing directions.