Interpolation-Based Animation - Computer Animation: Algorithms and Techniques - page 152

Auxiliary grid Intermediate grid

0 0

1 1

2 2

3

3

“column lines”

0

0 0

0

1

1

2 2

3

3 1

1

4

4

5 5

6

6

2

7
8 . . .

7
. . .

2

grid coordinates

3

3

pixel coordinates

3

3

2

2

1

1

0

0

0 1 2 3 4 5 6 7 8 . . . 0 1 2 3 4 5 6 7 8 . . .

Use row index coordinates to
determine the pixel coordinates
in auxiliary image

For a given pixel in the intermediate
image, determine the coordinates
in terms of row indices

FIGURE 4.46
Establishing the auxiliary pixel range for a pixel of the intermediate image (e.g., pixel 6 of the intermediate grid
maps to pixel coordinates 3.5 to 5 of the auxiliary image).

important features are presumably (if the user has done a good job of establishing the grids on
the two images) in similar positions. At this point the images can be cross-dissolved on a pixel-
by-pixel basis. The cross-dissolve is merely a blend of the two colors from corresponding pixels
( Eq. 4.9 ) .

C½½¼ a C 1 ½½þ ð 1 a ÞC 2 ½½ (4.9)