Caption: Figure 3: Projecting the 3D coordinate system
into a 2D coordinate system.
The establishment of a craniofacial 3D coordinate system
has been described in many reports [11-14]; in this study, we chose the lateral orbital rim to set the coronal plane because it could make the coordinates consistent with the clinical exophthalmos measurement.
The global (World) 3D coordinate system
is assumed as XYZ system with X-axis horizontally to the right, Y-axis vertical up, and Z-axis out of the computer screen.
Axes--SketchUp uses a 3D coordinate system
, similar to AutoCAD, where points in space are identified by position along the drawing axes identifiable by their color: red, green, or blue.
The field of view of this virtual camera forms an infinite four-sided pyramid in the 3D coordinate system
. The four faces of this 3D pyramid correspond to the four edges of the 2D viewing area.
Advanced axis locking enables the user to lock one or two axes about a user-defined localized 3D coordinate system
in any X, Y, or Z orientation.