9

Cameras 1367
movement to be vertical or horizontal only with
the
Shif t key .
You can move a selected camera so its view
matches that of a Perspective, Spotlight, or another
Camera v iew.
Choosing a Camera for Ver tical V iews
If you need an animated camera to look vert ically
upward or downward, use a free camera. If you u se
atargetcamerayoumightrunintoaproblemof
unexpected movement. The program constrains a
target camera’s up-vector (its local positive Y axis)
tobeascloseaspossibletotheworldpositiveZ
axis. This is no problem when you are working
with a static camera. However, if you animate the
camera and put it in a nearly vert ical position,
either up or down, the progr am flips the Camera
view to prevent the up-vector from becoming
undefined. This creates sudden changes of view.
Came ra Objec t Ico ns
Camera objects are visible in v iewports unless
you choose not to display them. However , the
geometry that appears in the v iewport is only
an icon meant to show you where the camera is
located and how it is oriented.
Target cameras (page 2–1371) create a double icon,
representing the camera (a blue box intersecting a
blue triangle) and the c amera target (a blue box).
Free cameras (page 2–1370) create a single icon,
representing the camera and its field of view.
A free camera has no target. A target camera has a target
sub-object.
Yo u c a n n o t s h a d e c a m e r a o b j e c t s . H o w e v e r, y o u
can render their icons using Animation menu >
Make Preview and turning on Cameras in the
Display In Preview g roup.
The display of camera object icons is not scaled
when you change the scale of the viewport. When
youzoominonacamera,forexample,theicon
size does not change. To change the size of camera
object icons, you can use the Viewports panel (page
3–821) of the Preferences dialog, and change the
value of Non-Scaling Object Size.
Scaletransformshavethefollowingeffectsona
camera object:
• Uniform Scale has no effect on a target camera,
but does change the f ree camera’s Target
Distance setting.
• Non-Uniform Scale and Squash change the size
andshapeofthefreecamera’sFOVcone.You
see the effect in the v iewpor t, but the camera’s
parameters do not update. Non-Uniform Scale
and S quash will change the size and shape of a
target camera’s icon, but have no visible effect
in the viewport.
mental ra y Camer a S ha ders
When you use the mental ray renderer (page
3–78),youcanapplyshaderstothecameraused
to render the scene. Specifically, you can assign
shaders to modify the camera’s lens, its output, or