Graphics Reference
In-Depth Information
prewarp
postwarp
prewarp
(a)
(b)
Figure 5.29.
(a) The camera configuration for view morphing. The white image planes repre-
sent the original images and the striped image plane represents the synthesized image. The
only requirement is that the virtual camera center lies on the line connecting the source cam-
era centers. (b) Applying appropriate rectifying projective transformations (prewarps) to the
source images allows view interpolation to be applied to the intermediate gray image planes. A
postwarping projective transformation is used to rotate the virtual camera to the final striped
image.
prewarp
postwarp
prewarp
Figure 5.30.
An example of view morphing. The original source images at the upper left and
upper right are rectified by prewarping projective transformations to the images at the lower left
and lower right. These rectified images are interpolated using view interpolation to produce the
new synthetic image at the lower center, which is postwarped to produce the synthetic view at
the upper center. In this case, the four corners of the top face of the box were used to guide the
postwarp.
from each other and from the synthesized view. One way to select the postwarping
projective transformation is by linearly interpolating the vertices of a user-specified
quadrilateral in each of the source images, since four feature matches define a
projective transformation.
Seitz and Dyer observed that the method could also be used to generalize mor-
phing algorithms from the last section; that is, we generate a family of intermediate
views
M
to the
second source image. When we finely sample
t
, we obtain an effect of smoothly mov-
ing the camera from the position where the first image was taken to the position
(
t
)
in which
M
(
0
)
corresponds to the first source image and
M
(
1
)
