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f6cc031 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | <Poster Width="1734" Height="2602"> <Panel left="26" right="480" width="1671" height="396"> <Text>Overview</Text> <Text>DTF = Efficiently learnable non-parametric CRFs for discrete image labelling tasks</Text> <Text>• All factors (unary, pairwise, higher-order) are represented by decision trees</Text> <Text>• Decision trees are non-parametric</Text> <Text>• Efficient training of millions of parameters using pseudo-likelihood</Text> </Panel> <Panel left="26" right="879" width="1677" height="578"> <Text>Formally</Text> <Figure left="26" right="1002" width="299" height="279" no="1" OriWidth="0.180507" OriHeight="0.131907 " /> <Text>Graphical Model:</Text> <Text>Factor types</Text> <Figure left="331" right="1028" width="303" height="243" no="2" OriWidth="0.196078" OriHeight="0.118093 " /> <Text>Factor Graph</Text> <Text>Energy</Text> <Text>Energy linear in w</Text> <Text>Example pairwise factor</Text> <Figure left="1382" right="1027" width="326" height="336" no="3" OriWidth="0.155133" OriHeight="0.111408 " /> </Panel> <Panel left="33" right="1458" width="1666" height="347"> <Text>Special Cases</Text> <Text>• Unary factors only = Decision Forest, with learned leaf node distributions</Text> <Text>Zero-depth trees (pairwise factors) = MRF</Text> <Text>• Conditional (pairwise factors) = CRF</Text> <Figure left="1289" right="1563" width="270" height="169" no="4" OriWidth="0.190888" OriHeight="0.114973 " /> <Figure left="784" right="1635" width="383" height="161" no="5" OriWidth="0.194925" OriHeight="0.114973 " /> </Panel> <Panel left="26" right="1805" width="1671" height="399"> <Text>Algorithm - Overview</Text> <Text>Training</Text> <Text>1.Define connective structure (factor types)</Text> <Text>2.Train all decision trees (split functions) separately</Text> <Text>3.Jointly optimize all weights</Text> <Text>Testing (2 options)</Text> <Text>•“Unroll” factor graph:</Text> <Text>run: BP, TRW, QPBO, etc.</Text> <Text>•Don’t “unroll” factor graph:</Text> <Text>run Gibbs Sampling; Simulated Annealing</Text> </Panel> <Panel left="24" right="2203" width="1672" height="352"> <Text>Training of weights “w”</Text> <Text>•Maximum Pseudo-Likelihood training, convex optimization problem</Text> <Text>Converges in practice after 150-200 L-BFGS iterations</Text> <Text>Efficient even for large graphs (e.g. 12 connected, 1.47M weights, 22mins)</Text> <Text>•Is parallel on the variable level</Text> <Text>•Variable sub-sampling possible</Text> <Text>Code will be made available next month!</Text> </Panel> </Poster> |