2009

Horizon line displayed in a camera viewport
A camera is level when it and its target are the same height from the world
coordinate plane. In other words, the camera’s local Z axis is parallel to the
world plane. When the camera is level, the horizon line is centered in the
viewport. As the camera tilts up, the horizon line lowers; as it tilts down, the
horizon line raises.
The horizon line control is in the camera’s
Parameters rollout on page 5210.
The horizon line can help you match the perspective of your scene to the
perspective of a still image. In general, matching perspective involves the
following steps:
1 Display the horizon line. Use it to help you adjust the camera and target
so they are level.
2 Display the image in the camera viewport. Use Views > Viewport
Background and choose Files in the Background Source group.
If the image's horizon and the camera horizon don't match, you have to
offset the image, perhaps by using a paint program.
5224 | Chapter 18 Lights and Cameras