9

1390 Chapter 15: Lights and Cameras
objects from this list to assign screen coordinate
points.NotethatifyouselectaCamPointobjectin
the viewport, it‘s highlighted in this list as well.
Input S creen Coordinates —
X/Y —
Fine-tunes the position of the screen
coordinate points in 2D space.
Use Thi s Point—Turns off a specific coordinate
point without deleting it. Select the corresponding
CamPoint in the list, and then turn off Use
This Point. This feature is typically used for
troubleshooting when the Current Camera Error
is too high (greater than five, for example).
Assign Position—Click a loca tion on the viewport
bitmap to place a screen coordinate point visually
against the background image. The point you
place corresponds to the currently selected
CamPoint object. After act ivating the Assign
P osition button, select a CamPoint object from the
list, and then click in the viewport at a position
on the bitmap background that corresponds with
wheretheassociateCamPointobjectshouldbein
the3Dscene. Afterrepeatingthisprocesswith
each CamPoint object in the list, you can click
theCreateCamerabuttontocreateacamera
that matches the placed co ordinates with their
associate CamPoint objects.
Camera Match rollout
Cr e a te Came ra —Creates a camera in the scene
whose position, orientation, and field of view is
basedonthecurrentlocationoftheCamPoint
helpers and the assig ned screen coordinate points.
Modify Camera—Modifies the position, orientation
and FOV of an existing , selected camera based
on the CamPoint helpers and assigned screen
coordinate poin ts.
Iterations—Maximum number of iterations used
to calculate the camera position. Default is 500,
thoughastablesolutionisusuallyfoundinless
than 100 iterations.
Freeze FOV —Prevents the F OV (field of view) of
the camera from being changed when using the
Create Camera or Modify Camera buttons. Use if
theFOVofthecamerathattookthephotographis
known and you want to preserve it.
Current Camera Error—Displays the total error that
remains b etween the placed screen coordinate
points, the C amPoint helpers, and the camera
position after the final computation. The
calculations involved in the camera match are
seldom perfect. A good error r ange is about 0 to
1.5.
Clo se—Exits the Camera Match utility.