SLIDE 1 CS 4803 / 7643: Deep Learning
Zsolt Kira Georgia Tech
Topics:
– (Finish) Computing Gradients – Backprop in Conv Layers – Forward mode vs Reverse mode AD – Modern CNN Architectures
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The architecture of LeNet5
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Handwriting Recognition Example
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Translation Invariance
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Some Rotation Invariance
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Some Scale Invariance
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- There are several generations of ConvNets
– 2012 – 2014: AlexNet, ZNet, VGGNet
- Conv-Relu, Pooling, Fully connected, Softmax
- Deeper ones (VGGNet) tend to do better
– 2014
- Fully-convolutional networks for semantic segmentation
- Matrix outputs rather than just one probability distribution
– 2014-2016
- Fully-convolutional networks for classification
- Less parameters, faster than comparable Gen1 networks
- GoogleNet, ResNet
– 2014-2016
- Detection layers (proposals)
- Caption generation (combine with RNNs for language)
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An Aside
SLIDE 32 AlexNet: 60M params ZNet: 75M VGG: 138M GoogleNet: 5M
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SLIDE 35 Importance of Depth
depth decreases performance
vanishing/exploding gradients
- normalized initialization
- Batch normalization
- 2nd order methods
- Then, optimization
limitation
– Deeper network should be able to mimic shallow
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Localization and Detection
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Computer Vision Tasks
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Computer Vision Tasks
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Classification + Localization
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CLS - ImageNet
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Idea 1: Localization as Regression
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Per-Class vs. Class Agnostic
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Where to attach?
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Multiple Objects
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Human Pose Estimation
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Sliding Window: Overfeat
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Sliding Window: Overfeat
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Sliding Window: Overfeat
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Sliding Window: Overfeat
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Sliding Window: Overfeat
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Sliding Window: Overfeat
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Sliding Window: Overfeat
Why aren’t boxes across grid?
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Sliding Window: Overfeat
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Detection as Classification
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Detection as Classification
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Detection as Classification
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Detection as Classification
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Detection as Classification
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R-CNN
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Region of Interest (ROI) Pooling
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