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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 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 | <Poster Width="1942" Height="883"> <Panel left="18" right="129" width="465" height="411"> <Text>Introduction</Text> <Text>• Some object classes are hard to reconstruct</Text> <Text>– Lack of texture</Text> <Text>– Transparency</Text> <Text>– Reflection</Text> <Text>• Solution: shape prior</Text> <Text>– Shapes within object class similar</Text> <Text>– Local distribution of surface normals</Text> <Figure left="59" right="349" width="116" height="87" no="1" OriWidth="0.102312" OriHeight="0.0598749 " /> <Figure left="56" right="450" width="127" height="90" no="2" OriWidth="0.107514" OriHeight="0.0580876 " /> <Figure left="184" right="344" width="250" height="193" no="3" OriWidth="0.262428" OriHeight="0.152815 " /> </Panel> <Panel left="18" right="550" width="464" height="305"> <Text>Formulation</Text> <Text>• Baseline Method: Volumetric depth map fusion</Text> <Text>– Segmentation of a voxel space into free and occupied space: us ∈ [0, 1]</Text> <Text>• Shape prior formulation</Text> <Text>– Voxel space aligned with object of known class</Text> <Text>ix</Text> <Text>s∈ [0, 1] andi</Text> <Text>i x</Text> <Text>sP=1Labeling of a voxel space into 3 labels:</Text> <Text>free space, ground, object</Text> <Text>• Convex Energy</Text> <Text>– Unary term</Text> <Text>∗ Computed from depth maps, local preference for solid class</Text> <Text>– Smoothness term</Text> <Text>∗ Dependent on surface orientation, position and involved labels</Text> </Panel> <Panel left="495" right="132" width="465" height="378"> <Text>Overview</Text> <Text>• Locally, surface normals similar between different examples</Text> <Text>– Roof at the top of the car close to horizontal</Text> <Figure left="528" right="240" width="406" height="76" no="4" OriWidth="0" OriHeight="0 " /> <Text>• Local distribution of normals captured from training data</Text> <Text>• Input data regularized using trained local normal distributions</Text> <Text>• Trained anisotropic smoothness used for</Text> <Text>– free space ↔ object</Text> <Text>– ground ↔ object</Text> <Text>• ground ↔ free space generic smoothness</Text> <Text>• Label determined by smoothness</Text> </Panel> <Panel left="495" right="522" width="465" height="331"> <Text>Convex Energy</Text> <Text>∈ </Text> <Text>•iρ</Text> <Text>s :≥</Text> <Text>joint unary term at voxel s for label i</Text> <Text>•ijφ</Text> <Text>s :convex smoothness term at voxel s for labels i and j</Text> <Text>•ix</Text> <Text>s∈ [0, 1]: indicating whether label i is chosen at voxel s</Text> <Text>•ijx</Text> <Text>s−jix</Text> <Text>s3∈ [−1, 1] : represents the local surface orientation</Text> <Text>3• ek ∈ R : k-th canonical basis vector</Text> <Text>• Optimized using primal-dual algorithm [Chambolle and Pock 2011]</Text> </Panel> <Panel left="973" right="129" width="464" height="205"> <Text>Unary Term</Text> <Text>• Only indicates free or occupied space</Text> <Figure left="1094" right="226" width="280" height="94" no="5" OriWidth="0.315029" OriHeight="0.0764075 " /> </Panel> <Panel left="973" right="347" width="465" height="253"> <Text>Shape Prior Training</Text> <Figure left="987" right="381" width="456" height="57" no="6" OriWidth="0" OriHeight="0 " /> <Text>• Training data, mesh models</Text> <Text>• Transformed into volumetric models</Text> <Text>• Per voxel s</Text> <Text>– Acquire normal directions of all training samples</Text> <Text>– Generate histogram over normal directions</Text> <Text>– Probability of normal n at s, Ps (n) given by histogram</Text> </Panel> <Panel left="973" right="614" width="467" height="239"> <Text>Discrete Wulff Shape</Text> <Text>• φs (·) support function of a Wulff shape Wφs</Text> <Text>[Esedoglu and Osher 2004]</Text> <Text>– Wulff shape: convex shape</Text> <Text>• Intersection of half spaces as parameterization of Wφs</Text> <Text>– n half space normal</Text> <Text>–nd</Text> <Text>sdistance of half-space boundary to origin</Text> <Text>• We have φs (n) =nd</Text> <Text>s [Esedoglu and Osher 2004]</Text> <Text>•nd</Text> <Text>s= − log (Ps (n)), determined by training data</Text> <Figure left="1323" right="684" width="119" height="128" no="7" OriWidth="0" OriHeight="0 " /> </Panel> <Panel left="1450" right="130" width="464" height="155"> <Text>Trained Shape Prior</Text> <Figure left="1468" right="166" width="231" height="98" no="8" OriWidth="0.378613" OriHeight="0.123324 " /> <Figure left="1720" right="168" width="198" height="94" no="9" OriWidth="0.379191" OriHeight="0.142985 " /> <Text>Slices through the bottle shape prior: vertical, horizontal</Text> </Panel> <Panel left="1449" right="298" width="465" height="455"> <Text>Results</Text> <Figure left="1460" right="338" width="456" height="136" no="10" OriWidth="0.767052" OriHeight="0.195264 " /> <Figure left="1468" right="484" width="447" height="254" no="11" OriWidth="0.772254" OriHeight="0.340036 " /> <Text>Input image</Text> <Text>Depth map</Text> <Text>Vol. fusion</Text> <Text>Shape Prior</Text> </Panel> <Panel left="1452" right="770" width="463" height="82"> <Text>Acknowledgements</Text> <Text>We gratefully acknowledge the support of the 4DVideo</Text> <Text>ERC starting grant #210806 and V-Charge grant</Text> <Text>#269916 both under the EC’s FP7/2007-2013.</Text> <Figure left="1786" right="813" width="130" height="39" no="12" OriWidth="0" OriHeight="0 " /> </Panel> </Poster> |