We present an analysis of the effect of digitization at a moderate resolution on the determination of various morphological quantities for a model three‐dimensional digitized medium. Specifically, we study systems of digitized overlapping spheres which have many of the features found in man‐made and geologic materials. The goal of this paper is to demonstrate which quantities are most sensitive to the process of digitization and resolution. In addition, the question of whether three‐dimensional data sets are necessary to obtain reliable results concerning material structure is answered in the affirmative. ©1995 American Institute of Physics.