Presently, a new calibration scheme for the camera under the Scheimpflug condition is proposed, which represents an exact projection from the object through the lens to the inclined image sensors and also handles the distortion by the lens theoretically. By this scheme, a highly precise three-dimensional calibration can be carried out and thus the accurate three-dimensional projection, which is inevitable for the development of three-dimensional three-component 3D3C PIV, can be calculated. Preliminary tests show that the present scheme gives better projections than the normal projection scheme and much better results than the conventional two-dimensional third-order polynomial fit.