When you select Perspective, the following Projection Parameters are available:
Width at the Near View-Plane: Indicates the width of the view volume at the near view-plane.
Height at the Near View-Plane: Indicates the height of the view volume at the near view-plane.
Z-Value of the Near View-Plane: Specifies the Z-value of the near view-plane.
Z-Plane of the Far View-Plane: Specifies the Z-value of the far view-plane.