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Camera Tracker: Error Thresholds Rollout 655
tracker placement on the match computations.
This is best done with the nudge arrows. Turn on
the 3ds Max Auto Key button to record adjusted
match camera positions.
Sync Animation—Cont rols w hether the scene time
slider is advanced in step with the movie frames
during stepping. This is sometim es useful if you
have the movie set up as a n animated backg round
image in the match camera window. Check camera
positioning at the same ti me you check feature
positioning. This can slo w stepping substantially,
so it’s tur ned off by default.
Camer a Tr a cker : Er r or Thr esholds
Rollout
Utilities panel > Utilities rollout > More button > Utilities
dialog > Camera Tra cker > Error Thresholds rollout
The Camer a Tracker utility’s Er ror Thresholds
rollout attempts to identify feature tracking errors
by t aking measurements and comparing them to
the thresholds that you set up in this rollout. You
can use this detection can be used both during a
manual t racking review (see
Batch Track Rollout
(page 2–655)
) or during actual tracking to correct
errors using the Resample On Error control in the
Motion Tr ackers setup rollout (p age 2–650) .
Inter face
Match Error—A sum-of-differences-s quared
measureinRGBspaceofthebestmatchin
thecurrentframetothefeaturetargetfrom
the previous keyframe. The error shown is a
percentage of the maximum possible image
difference. Good matches are usually below 0.05
percent.
Variance Delta—ThedifferenceinRGBcolor
variance between the feature target image and
the cur rent best match. This measures whether
the target and match have s imilar color ranges
and can compensate for mistakes made by the
sum-of-differences measure.
Jump Delta—The tracker computes a moving
average for the preceding five frames and measures
the difference between that average and the jump
in the current frame. If this difference exceeds the
current Jump delta threshold, a potential error is
flagged. If the threshold is set to five, any jump
inthecurrentframethat’sfivepixelsmorethan
theaveragejumpinthelastfiveframesisflagged.
This picks up sudden accelerations rather than just
large jumps.
You can adjust the thresholds as needed and enable
or disabled individual measures in the detector
using the check boxes to the left of each measure.
Camera Track er: Batch Track
Rollout
Utilities panel > Utilities rollout > More button > Util ities
dialog > Camera Tracker > Batch Track rollout
The Camera Tracker utility’s Batch Track rollout
performs feature hands-off tracking once the
trackers have been set up. You can set up a set of
trackers, start a batch tracking of them all, and
then use the other tools in this panel to check for
and review detected tracking errors. This panel
also checks for tracking completion.
Procedure
To r ev iew and correct track ing errors:
1.
Select an error in the list.