Vanishing point to the axis which is cut by this image plane will have images that meet at a single vanishing point. Lines parallel to the other two axes will not form vanishing points as they are parallel to the image plane. This is one-point perspective. Similarly, when the image plane intersects two world-coordinate axes, lines parallel to those planes will meet form two vanishing points in the picture plane. This is called two-point perspective. In three-point perspective the image plane intersects the , , and axes and therefore lines parallel to these axes intersect, resulting in three different vanishing points. The
Skew lines value of the real number formula_4 determining where the point is on the line, and similarly for arbitrary point on the line through particular point in direction . The cross product of b and d is perpendicular to the lines, as is the unit vector The distance between the lines is then (if |b × d| is zero the lines are parallel and this method cannot be used). Expressing the two lines as vectors: Line 1: formula_7 Line 2: formula_8 The cross product of formula_9 and formula_10 is perpendicular to the lines. formula_11 The plane formed by the translations of