As V-STARS measures by triangulation, in theory only two photographs are needed, for a measurement. However, we recommend you take a minimum of four to six photographs. With four to six photographs you can self-calibrate the camera. Self-calibration is a powerful technique in which the camera is calibrated as a by-product of the measurement. This allows the camera to be calibrated at the time of measurement under the conditions that exist at the time of the measurement. In order to self-calibrate the camera you must take a minimum of six photographs if the object is essentially flat, and a minimum of four photographs if the object isn’t flat. Extra photographs also produce a more accurate and reliable measurement, and typically take little more time to measure so go ahead and take them. See Triangulation and Self-Calibration for more information.