Transcript Download presentation source

VMorph: Motion and Feature-Based
Video Metamorphosis
Robert Szewczyk
Andras Ferencz
Henry Andrews
Automatic Video Morphing
• Currently, to do a video morph, a user must:
– manually enter feature lines in a number of key frames
– linearly interpolate to find the feature lines in the remaining frames
– apply still morphing
• In order to reduce the amount of user input and time, and
improve morphing quality, our algorithm:
– Aggregates the feature lines into groups
– Tracks the groups of feature lines
– Morphs foreground and background separately
Groups of Feature Lines
• Ensure that lines within the group stay in the same relation
to one another
• Motion of a group of feature lines is described by an affine
transform
• No loss of flexibility: animator groups the lines, grouping
ranges from a single line per group to all feature lines in a
single group
Feature Line Group Tracking
• Compute the dense motion field MF using census transform
– need a dense motion field, since feature lines do not correspond to any
edges
• Translate all the points in a feature line group using MF
– allow for disappearance of any feature line
• Fit an affine transform T to the translated points
– currently: General Least Mean Squares, with a bit of robustness (discard a
percentage of largest outliers), future: General Least Median Squares
• Apply T to the feature line group to find the new location of
each line in the group
Image Segmentation
• Observation: foreground and background are distinct and
move differently
– When morphed simultaneously, different parts of the image
influence each other.
• Conclusion: they should be morphed separately
– still morphing is not aware of image segmentation
– for video sequences, the segmentation can be done automatically
• Background: use salient stills, reduce the problem to still
image morphing
• Foreground: morphing with a mask
Morphing With a Mask
Create Mask
Morph mask
Add Still
Mask Still
Background Reconstruction
Feature Line Tracking Results
Morphing results: VMorph vs. Still Image Morphing
• VMorph
• Still Image Morphing