Design & Implementation of a Wireless Design & Implementation of a Wireless Video Surveillance Systemy

Aakanksha Chowdhery*, Tan Zhang†, Victor Bahl*, Kyle Jamieson‡, Suman Banerjee†

*Microsoft Research ‡UCL/Princeton †UWisconsin Madison

Video Surveillance: Pervasive and UsefulVideo Surveillance: Pervasive and Useful

London & Beijing: 1 million cameras deployed

Intrusion detection – campus, airport, train stationCustomer analytics store toll booth parking garageCustomer analytics – store, toll booth, parking garageTraffic monitoring – cities, freeways

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Wireless surveillance camerasWireless surveillance cameras

Easy to install

No need for wired backhaul to camera

Comprehensive coverage

How do we build a large‐scale wireless video

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How do we build a large scale wireless video surveillance network?

Video Cameras overwhelm wireless capacity quicklydeo Ca e as o e e e ess capac ty qu c y

Wireless is a shared medium in scarce spectrum

Today’s wirelessSupports 20 cameras@1 Mbps streams

Wireless Coverage Area: 10,000 sq ft, q

Complete Surveillance coverage p gRequires 400 cameras@10 ft camera range 100 sq ft

Vigil: Wireless Video Surveillance SystemVigil: Wireless Video Surveillance System

Goals:Goals:

1. Maximize surveillance application accuracy1. Maximize surveillance application accuracy

2. Minimize wireless capacity usage

Techniques:Techniques:

Edge Redundancy Content-awareEdge Computing

Redundancy Suppression

Content-aware Traffic Scheduling

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Vigil: Wireless Video Surveillance SystemVigil: Wireless Video Surveillance System

Goals:Goals:

1. Maximize surveillance application accuracy1. Maximize surveillance application accuracy

2. Minimize wireless capacity usage

Techniques:Techniques:

Edge Redundancy Content-awareEdge Computing

Redundancy Suppression

Content-aware Traffic Scheduling

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Useful video content is sparse

Example: find a person of interest by face

Useful video content is sparse

Example: find a person of interest by face250 hours of video feed in busy office halls

1 f

2 faces, 3% >=3 faces, 1%

1 face, 16%

No faces, 80%

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Less than 20% feed has people

Edge Computing NodeEdge Computing Node

Edge Computing Node detects queried objectsg p g q j

ControllerController

Edge ComputingNode

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Vigil Architecture with Edge ComputingVigil Architecture with Edge Computing

F IDU l d!

ControllerQuery

Frame ID, Person Count

Upload!

ControllerQ y

9Frame ID, 

Person CountFrame ID, 

Person Count

Vigil only uploads relevant frames!

Vigil: Wireless Video Surveillance SystemVigil: Wireless Video Surveillance System

Goals:Goals:

1. Maximize surveillance application accuracy1. Maximize surveillance application accuracy

2. Minimize wireless capacity usage

Techniques:Techniques:

Edge Redundancy Content-awareEdge Computing

Redundancy Suppression

Content-aware Traffic Scheduling

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Video Codecs compress frames temporallyVideo Codecs compress frames temporally

Motion suppressed by difference coding (H.264)

How can we compress frames from multiple cameras?

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Compressing frames across camerasCompressing frames across cameras

Camera 1 Camera 2

Camera Cluster

How do we suppress redundant images between cameras in a cluster?

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between cameras in a cluster?

Vigil’s Redundancy Suppression AlgorithmVigil s Redundancy Suppression Algorithm

Camera 1 Camera 2

Camera 2 hasFrame Index 1 2 3 4 5

Camera 1 0 0 0 0 0

Camera 2 has higher utility

Step 1: Frame Utility = Number of queried objects in frameCamera 2 3 3 3 3 3

p y q jStep 2: Select frames from camera 2

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Vigil’s Redundancy Suppression AlgorithmVigil s Redundancy Suppression Algorithm

Camera 1 Camera 2

Camera 1 hasFrame Index 1 2 3 4 5

Camera 1 3 3 3 3 3

Camera 1 has higher utility

Step 1: Frame Utility = Number of queried objects in frameCamera 2 0 0 0 0 0

p y q jStep 2: Select frames from camera 1

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Vigil’s Redundancy Suppression AlgorithmVigil s Redundancy Suppression Algorithm

Camera 1 Camera 2

Camera 1 hasFrame Index 1 2 3 4 5

Camera 1 3 3 3 3 3

Camera 1 has higher utility

Step 1: Frame Utility = Number of queried objects in frame

Camera 2 2 2 2 2 2

Step 1: Frame Utility Number of queried objects in frameStep 2: Re-identify objects from camera 2 in camera 1

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Vigil’s Redundancy Suppression Algorithm: R id tifi tiRe-identification

Camera 1 Camera 2

Pixels of 2nd face  Pixels of 

Check if pixels

2nd face  

Frame Index 1 2 3 4 5

Camera 1 3 3 3 3 3

Check if pixels map to same 

physical location?

Step 1: Frame Utility = Number of queried objects in frame

Camera 2 2 2 2 2 2

Step 1: Frame Utility Number of queried objects in frameStep 2: Re-identify objects from camera 2 in camera 1

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Vigil’s Redundancy Suppression AlgorithmVigil s Redundancy Suppression Algorithm

Camera 1 Camera 2

Upload onlyFrame Index 1 2 3 4 5

Camera 1 3 3 3 3 3

Upload only change frames

Step 1: Frame Utility = Number of queried objects in frameCamera 2 2 2 2 2 2

p y q jStep 2: Re-identify objects from camera 2 in camera 1Step 3: Upload frames from camera 1 17

Vigil’s Redundancy Suppression AlgorithmVigil s Redundancy Suppression Algorithm

Step 3: Upload only change frames

Frame Utility= Number of faces detected

1 1 2 2 3

Upload! Upload! Upload!Upload! Upload! Upload!

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Vigil increases surveillance accuracy h i l it t twhen wireless capacity saturatesSingle cluster, 3 cameras, Medium activity of people

80%

100% Without Vigil Vigil

60%A

40%Accuracy

0%

20%

0%50 kbps 100 kbps 200 kbps 300 kbps

Available Wireless Capacity (kbps)

19100% accuracy = Upload all change framesVigil provides 1.7x accuracy for same wireless capacity!

Vigil increases surveillance accuracy when wireless capacity saturateswhen wireless capacity saturates

100%Single cluster, 3 cameras, High activity of people

80%

100%Without Vigil With Vigil

60%

40%Accuracy

20%

0%50 kbps 100 kbps 200 kbps 300 kbps

Available Wireless Capacity (kbps)

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Available Wireless Capacity (kbps)

Vigil provides ≈1.7x accuracy for same wireless capacity!

Vigil: Wireless Video Surveillance SystemVigil: Wireless Video Surveillance System

Goals:Goals:

1. Maximize surveillance application accuracy1. Maximize surveillance application accuracy

2. Minimize wireless capacity usage

Techniques:Techniques:

Edge Redundancy Content-awareEdge Computing

Redundancy Suppression

Content-aware Traffic Scheduling

I ill li ti h21

Increases surveillance application accuracy when available wireless capacity is limited in camera clusters

Vigil: Wireless Video Surveillance SystemVigil: Wireless Video Surveillance System

Goals:Goals:

1. Maximize surveillance application accuracy1. Maximize surveillance application accuracy

2. Minimize wireless capacity usage

Techniques:Techniques:

Edge Redundancy Content-awareEdge Computing

Redundancy Suppression

Content-aware Traffic Scheduling

P i iti l t ith bj t22

Prioritizes camera clusters with objects relevant to query

Hybrid surveillance-access networkHybrid surveillance access network

Reuse bandwidth savings to provide Wi-Fi access

F ID

g p& recoup the surveillance network cost

Controller

Frame ID, Person Count

Controller WiFi traffic

WiFi AP

WiFi traffic

WiFi t ffi

23Frame ID, 

Person CountFrame ID, 

Person Count

WiFi traffic

System DeploymentSystem Deployment

Whitespaces in MSR UWisconsin; Wi-Fi in UCLWhitespaces in MSR, UWisconsin; Wi Fi in UCL- Using a 802.11 baseband protocol- Integrated frequency translator to operate at UHF bandg q y p

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System Deployment at Microsoft ResearchSystem Deployment at Microsoft Research

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Related workRelated work

CloudletsCloudletsVM-based Cloudlets (Pervasive Computing ’09)Dynamic offloading of mobile apps – Maui (MobiSys’10),Gabriel (MobiSys’14)

Cloud-based video surveillance systemsWired - IBM’s Smart Surveillance System (’05)Wireless Dropcam ships video to cloudWireless - Dropcam ships video to cloud

Video Compression algorithmsMPEG-4 H 264 eliminate redundancy across framesMPEG-4, H.264 eliminate redundancy across framesImage similarity - Re-identification, Perceptual hashing

Vision analytic algorithms on MobileVision analytic algorithms on MobileHarr Cascade based face detection – Glimpse (MobiSys’14)SIFT based object detection- CarSafe (MobiSys’13)

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ConclusionsConclusions

Vigil’s edge computing provides at least 5x reduction in frames to be uploaded

Vigil’s redundancy suppression provides 1.7xVigil s redundancy suppression provides 1.7x surveillance accuracy when available wireless capacity is limitedcapacity is limited

Vigil’s content a are traffic sched ling ploadsVigil’s content-aware traffic scheduling uploads 25% more objects relevant to the user’s query

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