Reconstructing three-dimensional objects, both surface and interior intensities, from serial cross-sections not only makes slicing from any arbitrary angle possible but also provides accurate quantitative information for various purposes. However, the only technique available for intensity interpolation is the straightforward linear interpolation method which is technically unsound and groundless. In this paper, an intensity interpolation method for two regions of interest lying on two consecutive cross-sections is proposed. Although the intensity is interpolated linearly, the corresponding points involved in interpolation are carefully selected. The result is compared with the straightforward linear interpolation method.