Graphics Reference
In-Depth Information
Figure 13.6.
The coordinate system and the positions of the model for the scene of
Figure 13.1.
allows straightforward description of the location and orientation of the model and
camera in the scene. Figure 13.6 shows a coordinate system where the following
are true.
• The origin is located at the center of the 8 cm
×
8 cm paper.
•The x -and z -axes are parallel to the edges of the papers. Notice that we
have followed the computer graphics convention where the y -axis points
upward from the xz horizontal plane.
• The unit of measurement is in centimeters.
With these choices, all the vertex positions of the papers can be conveniently
identified:
V a =
4
.
0cm
,
0
.
0cm
,
4
.
0cm
) ,
V b =(
.
,
.
,
.
) ,
4
0cm
0
0cm
4
0cm
Large paper:
V c
=(
4
.
0cm
,
0
.
0cm
, −
4
.
0cm
) ,
V d =
4
.
0cm
,
0
.
0cm
, −
4
.
0cm
) ,
 
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