The model between the object and the occlusion background was established by the relationship of perspective projection between the viewpoint, object and background. The error equation was obtained for the coordinates of the viewpoint and the distance to background. The errors of the angle of rotation were analyzed based on the Mont Carlo method. The results show that the relationship between the pixel offset and the errors of parameters is linear, the viewpoint coordinates and the distance errors have different influence in different initial conditions. The pixel offset which is caused by X coordinate and Y coordinate of viewpoint is much higher than the offset which is caused by Z coordinate or the distance to object. The pixel offset which is caused by the pitch angle and the yaw angle is much higher than the offset which is caused by the rolling angle.