Natural 3D images can be generated by displaying high-density directional images. In order to display real 3D scenes, a 3D camera technique which generates high-density directional images of real 3D scenes is required. The most promising method is to generate them by using an interpolation algorithm from multiple images captured by horizontally aligned multiple cameras. In this study we examined four different simple interpolation algorithms. The algorithm that utilizes one representative object distance as a priori was found to be the most effective one. This technique offers the fast interpolation. However, there is a tradeoff between the number of cameras and the depth of 3D objects. The allowable depth for 3D objects is reported.