nying videos show the continuous face appearance changes, and the radiance
environment map is shown on the righthand side of the face. (The environment
rotates in such a direction that the environment in front of the person turns from
the person's right to the person's left). From the middle image to the right in
the image sequence, the frontal environment turns to the person's left side. On
the fourth image, we can see that part of his right face gets darker. On the last
image, a larger region on his right face becomes darker. This is consistent with
the rotation of the lighting environment.
Figure 8.5 shows a different person in a similar lighting environment. For this
example, we have captured the ground truth images at various rotation angles
so that we are able to do a side-by-side comparison. The top row images are the
ground truth images while the images at the bottom are the synthesized results
with the middle image as the input. We can see that the synthesized results
match very well with the ground truth images. There are some small differences
mainly on the first and last images due to specular reflections (According to
Marschner et al. [Marschner et al., 1999], human skin is almost Lambertian at
small light incidence angles and has strong non-Lambertian scattering at higher
Figure 8.5. Thecomparisonofsynthesized results and ground truth. The top row is the ground
truth. The bottom row is synthesized result, where the middle image is the input.
The third example is shown in Figure 8.6. Again, the middle image is the
input. In this example, the lights mainly come from two sides of the face. The
bright white light on the person's right face comes from sky light and the reddish
light on his left face comes from the sun light reflected by a red-brick building.
The image sequence shows a 180° rotation of the lighting environment.