9.5.2

252 • CHAPTER 7
OBJECTS MENU • SPLINES • 253
None
This method of interpolation locates points only at the vertices of
a spline, using no additional intermediate points. You cannot enter
values into the Number or Angle boxes. For B-splines, the vertices,
and therefore points, might not be located on the spline curve.
Natural
This interpolation type rst locates points at spline vertices. In the
case of B-splines, points are located at positions on the spline curve
closest to the spline vertices. Number (N) corresponds to the number
of intermediate points between vertices. The points are positioned
closer together on areas of the spline with more curvature. You
cannot enter values into the Angle box. The interpolation is not
affected by reversing the point order.
Uniform
This interpolation subdivides the spline so that the distance between
any two consecutive points, as measured along the spline curvature,
is constant. One point is always located at the beginning vertex.
For open splines, a point is also located at the ending vertex. Other
points generally do not coincide with vertices. You cannot enter
values into the Angle box. The interpolation is not affected by
reversing the point order.
Adaptive
This interpolation type sets intermediate points whenever the angle
deviation of the curve is larger than the value given in Angle. The
points of the resulting curve pass through the vertices. If a spline
has several segments, then the value of Angle will apply to each
segment. The Adaptive method gives the best results in rendering,
hence it is the default interpolation method. You cannot enter values
into the Number box.
For Natural and Uniform interpolation, the number of intermediate points is calculated as follows:
 Open spline: ((Number + 1) * (number of vertices - 1)) + 1
 Closed spline: (Number +1) * number of vertices
So an open spline with four vertices and a Number of 2 will contain ((2+1)*(4-1))+1=10 intermediate
points. If the spline is then closed, a further (virtual) vertex is added — the number of intermediate
points will then be (2+1)*4=12. This ensures that a spline is not more roughly divided when you close
it.