Shape and size of rocks are important physical characteristics of aggregates used in engineering and for interpretation of the genesis of naturally occurring sediment. Several image processing programs are available for measure the size and shape of various types of objects. The accuracy and reproducibility of results of a new imaging method and new matlab based 3D imaging program has been studied. 3D results are obtained by coupling two images of particles one of their largest and one of the smallest projected areas. The accuracy of results depends on the focal length used for imaging as well as the positioning of particles in the view field.