[Insight-users] about the number of the control points of the Cubic BSpline

[Bing Jian]

think about following case:
   Suppose your image is a single patch, i.e. it is not
partitioned at all, then you need a 3*3 board to cover
the image, where the image exactly lies in the center
block of the 3*3 board. Therefore the number of control
points should be 4*4, please see below:

        1    2    3
      *   *     *   *
  1
      *   *     *   *
  2         Img
      *   *     *   *
  3
      *   *     *   *

  the control points are represented by "*"s.



-- 
Best wishes,
Bing Jian
bjian at cise.ufl.edu


On Sun, 18 Jul 2004, Yixun Liu wrote:

>
> Hi ITKUsers,
>
> I do not fully understand the meaning of the following sentences about  the number of the control points of BSpline.
>
> //  Since we are using a BSpline of order 3, the coverage of the BSpling grid
> //  should exceed by one the spatial extent of the image on the lower region of
> //  image indices, and by two grid points on the upper region of image indices.
>
>
> In my opinion, if the internal grid can just cover the full image, we only need exceed by one grid instead of two on the upper region of image indices.
>
> Hope your confirmation!
>
> Regards,
>
> Yixun Liu
>
>