Imaging gaps will appear in the field of view for a mapping camera due to the convergence angle when it uses a interleaving assembly of focal plane. In order to solve the problem above, an algorithm of minimum overlapping pixels was proposed by considering convergence angle and without camera pitch. Firstly, an imaging model for the front view camera was established according to the imaging principle of mapping camera. The reason that imaging gaps appear was analyzed. Then, the mathematical expressions of imaging gaps and overlaps of odd and even quantity CCD assemblies were derived, the formula for computing the minimum number overlapping pixels between adjacent CCDs that can avoid the imaging gaps was obtained, and the error was analyzed. Finally, the algorithm was applied to an engineering example, and the effect of earth curvature was analyzed. The instance shows that the imaging gaps and the minimum number of overlapping pixels in the engineering instance are 1 141.491 μm and 115 in maximum respectively. It indicates that the proposed algorithm can calculate the minimum number of overlapping pixels of the mapping camera and the theoretical error is less than 1 pixel.