The structure of the image synthesis process naturally leads to the use of object-oriented software design and many existing rendering systems are based on some kind of object-oriented approach. However, some areas in image synthesis, such as global illumination, were considered to violate some fundamental principles of object-orientation. In this paper, we suggest a design approach which overcomes this apparent inconsistencies and allows for a uniform use of object-oriented techniques in image synthesis. The second part of the paper discusses attributes in hierarchical scene descriptions using a new object-oriented approach.