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Making the Right Moves: Guiding α-Expansion using Local Primal-Dual Gaps Dhruv Batra (TTI Chicago), Pushmeet Kohli (Microsoft Research Cambridge). Primal-Dual Interpretation of Expansion. Algorithm. More Results. MAP Inference in MRFs. LPDG Full Sweep. LP Relaxations. - PowerPoint PPT Presentation
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Making the Right Moves: Guiding α-Expansion using Local Primal-Dual GapsDhruv Batra (TTI Chicago), Pushmeet Kohli (Microsoft Research Cambridge)
MAP Inference in MRFs
Expansion Algorithm
Primal-Dual Interpretation of Expansion
Local Primal-Dual Gap (LPDG)
Algorithm
Results
More Results
Graph Structure
MAP Inference
Variables Node / Edge Potentials
Energy / Cost Function
Current Soln 2-Label Problem + GC New Soln
Loop over α
α-Expansionα
Traditional Loop:
LPDG Loop:
Adaptive Re-ordering of Labels leads to Massive Speed-ups!
LP Relaxations [Schlesinger ‘76; Wainwright et al. ’05; Komodakis et al. ‘05]
Primal LP Dual LP
NormalizationNormalization
MarginalizationMarginalization
LagrangianLagrangian
MultipliersMultipliers
Local Primal-Dual Gap
Interpretation
Proposed Label Scores
LPDG-crisp
LPDG-deficit
LPDG-tradeoff
LPDG Full Sweep
LPDG Partial Sweep
Ordering of Expanded Labels
Move Number
Classical Expansions
Our Guided Expansions
1 Airplane Car
2 Bicycle Person
3 Bird Motorbike
4 Boat Train
5 Bottle Airplane
1 Airplane Sheep
2 Bicycle Dog
3 Bird Bird
4 Boat Cow
5 Bottle Cat
1 Airplane Airplane
2 Bicycle Bird
3 Bird Dog
4 Boat TV
5 Bottle Train
LPDG correlated with decrease in energy!
Cuts Runtime by ~50%
Partial Sweeps Effect of Initialization