Scaling Face Recognition with Big Data
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Transcript of Scaling Face Recognition with Big Data
@ITCAMPRO #ITCAMP17Community Conference for IT Professionals
Scaling Face Recognition
with Big Data
Bogdan BOCȘE
Solutions Architect & Co-founder VisageCloud
https://VisageCloud.com
https://www.linkedin.com/in/bogdanbocse/
https://twitter.com/bocse
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• How to learn ?
• What to learn?
• Defining learning objectives
• How to scale learning?
• Gotchas
• VisageCloud
–Architecture
–Use Cases
Agenda
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• What questions to ask before writing the code?
• How to look at the data before feeding it to the
machine?
• What is the state of the art regarding ML?
• What frameworks to use?
• What are the common traps to avoid?
• How to design for scale?
Objectives
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HOW TO LEARN?
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Vision
• Convolutional Neural Networks
• Inception Paper
NLP
• Word2Vec
• GloVe: Global Vectors for Words Representation
Generic
• Classification
• Prediction
How to Learn?
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Convolutional Neural Networks: Big Picture
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• Pooling / Max Pooling
• Convolution
• Fully Connected Activation–Activation Function, eg. ReLu
Convolutional Neural Networks : Components
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• Learning is an optimization problem
–Find parameters of a system (neural network) that minimize a fixed error function
–Not unlike planning orbital paths
• Defining the network architecture
• Defining the training algorithm
–Stochastic Gradient Descent
• With momentum
• With noisy
Taking a Step Back: The Math
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• DeepLearning4j– Independent company
– Java interface with C-bindings for performance
• TensorFlow– Python & C++ API
– Developed by Google
– Compatible with TPU
• Torch– Developed by Facebook
– Written in LuaJIT, with Python bindings
Frameworks
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WHAT TO LEARN?
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• Public data sets
– Labelled Faces in the Wild (LFW)
–Youtube faces
–Kaggle
• Private data sets
• Build your own
–Outsourcing: Mechanical Turk
–Crowsourcing: ReCaptcha model
Data Sets
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Preparing Data
Clean data
Cropping
Structure
Homogeneity
Normalization
Histograms
Filtering
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• Machine learning is not magic
• If you can’t understand the data, a machine probably
won’t either
• Preprocessing makes the difference between results
• Applying filters, normalization, anomaly detection is
computationally inexpensive
Preparing Data
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DEFINING LEARNING OBJECTIVES
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• Supervised
–Classification
–Scoring and regression
– Identification
• Unsupervised
–Clustering
Defining learning objectives
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• Projecting input onto a fixed set of classes
• “Don’t use a cannon to kill a fly”
–Support Vector Machines
• Linear
• Radial Based Functions
Classification
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• Embedding
–Projecting input (image) onto an vector space with a
known property
• Triplet Loss Function
Identification
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• Splitting a set of items into non-overlapping subsets,
based on item attributes
• Counting people in video streams
• Algorithms:
–Fixed threshold
–K-means
–Rank-order clustering
Clustering
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HOW TO SCALE LEARNING?
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• Scaling training
– Requires shared memory space
– Vertical scaling
• GPU
• Soon-to-come: TPU (tensor processing unit)
• Scaling evaluation
– Shared nothing architecture
–Neural network/classifier rarely change
– Load balancing pattern
– Partitioning data if needed
How to scale learning?
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• There is no “reduce” for neural networks
• Averaging weights/parameters
–Usually not a good idea
• Genetic algorithms
– Requires a lot of processing power
– Running independent iterations on different machines
– Crossover between weights/parameters of independently trained neural networks after each epoch
Ideas for horizontal scaling
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GOTCHAS
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• Our 2D and 3D intuition often fails in high dimensions
• Distances tend to become relatively “the same” as
number of dimensions increases
• Dimensionality reduction
– Embedding functions
– Principal component analysis
The Curse of Dimensionality
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• “The bottom of a valley is not necessarily the lowest
point on Earth”
• Learning algorithms may get stuck in local optima
• Using momentum or some random noise reduces
this possibility
• Using genetic algorithms can be even more robust,
but it’s computationally expensive
Local Optima
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Visualizing Local Optima
monkey saddle
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“Based on state-of-the-art machine learning, our
weather forecast system can predict tomorrow’s
weather with 72% accuracy”
Evaluating of Learning
You get the same results by saying “it’s going to be the same as today”
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• Don’t test on the data you train on–Use different data set
– Split the data sets you have
• Beware of data biases– Confirmation bias
– Survivorship bias
– Selection bias
• Compare against a benchmark, even a dummy one– Coin flip
– Linear algorithms
– “Same-as-before”
Evaluation of Learning
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Architecture and Use Cases
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High Level Architecture
VisageCloud Production
HAProxy(reverse proxy)
Image StorageAWS S3
Service(API Controller)
Cassandra Containers
(Docker)
Neural Networks(OpenCV, Dlib,
Torch, pixie magic)CQL Binary
HTTP
API Consumer(Customer Infrastructure)
HTTPS
HTTP
HTTPS
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Detect faces
Align facesPre-
processingFeature
extractionFeature
comparison
Processing Pipeline
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• The collection
–Slice of data used together
– 10K-100K records
• The Cache-Inside Pattern
– Loading / preloading collection in one application server
–Content based routing/balancing to maximize cache hits
–No logic in the database layer
–Requires periodic polling for updates
• Weaker consistency
Partitioning Data: Application Level Logic
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Partitioning Data: Application Level Logic
Application Layer
Application Application Application
Cassandra (Database Layer)
Cassandra Node Cassandra Node Cassandra Node Cassandra Node
Content-based balancing/routing
Preload collectionPoll for updatesWrite updates
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• Perform comparison logic in database
–User Defined Aggregate Functions
• Removes the need to move data around between
application and database
• Harder to deploy/test
• Stronger consistency
Partitioning Data: Application Level Logic
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• It’s math, not magic
• If you don’t understand the data, neither will the
machine
• Preprocessing makes the difference
• Test against a benchmark, any benchmark
• Evaluate first, scale later
Key Take-away
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+(40) 724 714 234
https://www.linkedin.com/in/bogdanbocse/
https://twitter.com/bocse
Let’s keep in touch
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Q & A