PhotoModeler always needs a ‘description’ of the camera, e.g. focal length of the lens, format size of the image, and the image center. PhotoModeler may work with approximate values given by the camera manufacturer, or EXIF data if available, and the 3D data produced may look reasonable. But if you calibrate the camera using the Camera Calibration, the camera values used by PhotoModeler will be much more accurate. The Calibrator also calculates and compensates for lens distortion. When the camera and lens are more accurately described, the models you produce will also be more accurate.