Information Technology Reference
In-Depth Information
2.2 Reflection Models
Using the color-restored
shouhekiga
images, we attempted to create a representation
of
shouhekiga
that also expresses the characteristics of the pigments used. As stated
above, pigments have different granule diameters, which, as they become larger,
render the surface of a painting coarser, due to the diminishing intensity of reflected
light. We tried to recreate this effect using a surface scattering model that takes
pigment characteristics into account. In the study we used the microfacet distribution
function (Beckman distribution function, Formula (1).
2
⎛
⎞
1
tan
d
⎛
⎞
⎜
⎜
⎝
⎟
⎟
⎠
D
(
x
,
k
,
k
)
=
exp
−
⎜
⎝
⎟
⎠
(1)
2
1
2
4
S
cos
d
S
[
d
=
n
⋅
h
]
here
x
= denotes a sample point,
k
= the incident vector
k
= the reflecting vector,
n
= the normal vector
h
= the half-angle vector,
S
= the coarseness parameter
Fig. 3.
Representation of
shouhekiga
using pigment reflection model
2.3 Gold Foil Reflection Model
Since Nishi Hongwanji has large numbers of gilded art objects, realistic
representation of the surfaces of such objects constitutes an important aspect of the
digital archiving. Gold foil, thinly spread gold obtained by striking the metal wrapped
in deerskin or a similar material, is cut into squares for application. A gilded surface is
minutely uneven and reflects light diffusely. As well, gold foil being a metal, it is
