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DCL:GRPH1:Summary:Perspective Transformation

1.6.1 Transformation Parameters

Eye point

(XEYE3, YEYE3, ZEYE3)
An eye point in 3-D space. Think of holding a camera in this position.

Center of Focus

(XOBJ3, YOBJ3, ZOBJ3)
The point at which the line of sight is aimed in 3-D space. Think of it as the position of the subject of the photograph. The plane perpendicular to the line of sight (line connecting the eye point and center of focus) and passing through the center of focus is the plane of projection. In other words, point (X, Y, Z) in 3-D space is projected onto a point where the line connecting the point in 3-D space and the eye point intersects with the plane of projection.

Angle of View

(ANGLE3)
The length of the line projected onto the plane at this angle from the eye point is the unit length in a normalized rectangular coordinate system.

Tilt

(TILT3)
Inclination of the Z-axis. Equivalent to the tilt around the optical axis for camera. When this angle is 0, the Z-axis in 3-D space becomes parallel to the Y-axis in s normalized rectangular coordinate system. When the line of sight is parallel to the Z-axis, the Y-axis becomes the standard line.

Offset

(XOFF3, YOFF3)
The position of the center of focus projected onto a normalized rectangular coordinate system is specified with its location relative to center. Normally, this value is (0,0).

Position in the 2-D Plane

(IXC3, IYC3, SEC3)
Specifies where the 2-D plane will be positioned in 3-D space. ixc3, iyc3 specifies the 3-D coordinate corresponding to the X and Y coordinates in the 2-D plane in the form of numbers (1, 2, 3), which represent the X, Y, and Z axes, respectively. When negative values are specified for these values, the values are assigned with inversed signs. sec3 is the remaining coordinate value.