• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • Subscribe
  • Advertise

Sensor Tips

Sensor Product News, Tips, and learning resources for the Design Engineering Professional.

  • Motion Sensing
  • Vision systems
    • Smart cameras
    • Vision software
    • Lighting
    • Optics
  • Pressure
  • Speed
  • Temperature
  • Suppliers
  • Video
    • EE Videos
    • Teardown Videos
  • EE Learning Center
    • Design Guides
    • Tech Toolboxes

How can you detect hidden cameras invading your privacy?

November 29, 2021 By Randy Frank

Using the time-of-flight (ToF) sensor on commodity smartphones, researchers at the National University of Singapore and Yonsei University have developed a technique to detect tiny hidden spy cameras concealed in privacy-invading locations, such as hotels and bathrooms. With small form factors and lens diameters as small as 1 to 2 millimeters, hidden cameras are difficult to detect — even though they are hiding in plain sight.

Called laser-assisted photography detection (LAPD), the technique is implemented as a smartphone app that emits laser signals from the ToF sensor and uses computer vision and machine learning to locate the unique reflections from hidden cameras. The ToF sensor technique is an alternative to wireless detection approaches that other researchers are pursuing by detecting wireless traffic. LAPD does more than detect the presence of the camera. It also locates the hidden camera that may only record the data on a local memory card and not transmit any wireless data.

Challenges that had be overcome include:

  • The varying reflectivity of objects that embed the hidden cameras
  • Reliably (minimal false positives) identify hidden camera (constrained by the ToF sensor’s number of pixels and number of bits per pixel)
  • Limitation of reflections due to their optical properties

To address the first issue, the ToF sensor in the phone must be located an ideal range from the hidden camera. Using augmented reality, LAPD guides the user to the ideal location. The ideal distance is calculated by determining the objects reflectivity at various distances.

To overcome the second challenge, researchers designed and implemented a chain of filters including deep-learning based filters that incorporate multi-modal information including depth and reflection intensities. This eliminated false positives.

Third, since the reflections are limited by their optical properties, they are only observed within a constrained angle of a 20° field-of-view (FoV) cone. The solution was an FoV filter to eliminate the remaining reflections – or potential hidden cameras. These appear highly reflective outside of the constrained angle.

The ideal distance, maximum visible FoV and retro-reflection in ToF system.

 

How effective is this approach? Using 379 observers, LAPD found 88.9% of the hidden test cameras vs. 46% discovered by the human observers.

Reference

LAPD: Hidden Spy Camera Detection using Smartphone Time-of-Flight Sensors

Filed Under: Distance, Featured, Frequently Asked Question (FAQ), laser Tagged With: national university of singapore

Primary Sidebar

Featured Contributions

Integrating MEMS technology into next-gen vehicle safety features

Fire prevention through the Internet

Beyond the drivetrain: sensor innovation in automotive

Sensors in American football can help the game

Select and integrate sensors into IoT devices

More Featured Contributions

EE TECH TOOLBOX

“ee
Tech Toolbox: 5G Technology
This Tech Toolbox covers the basics of 5G technology plus a story about how engineers designed and built a prototype DSL router mostly from old cellphone parts. Download this first 5G/wired/wireless communications Tech Toolbox to learn more!

EE LEARNING CENTER

EE Learning Center
“sensor
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for EE professionals.

RSS Current EDABoard.com discussions

  • Electrochemical Front End do we need dual voltage rails and split ground
  • What tool can I use to draw circuit diagrams like this?
  • Microsoft Teams sound not working
  • BF999 Input and output impedance
  • floating node warning in LTSpice

RSS Current Electro-Tech-Online.com Discussions

  • How to make string LEDs?
  • PIC KIT 3 not able to program dsPIC
  • Display TFT ST7789 (OshonSoft Basic).
  • Remote Control By Location Part 2
  • Raise your hand if your car had one of these:

EE ENGINEERING TRAINING DAYS

engineering
“bills

RSS Featured White Papers

  • 4D Imaging Radar: Sensor Supremacy For Sustained L2+ Vehicle Enablement
  • Amphenol RF solutions enable the RF & video signal chains in industrial robots
  • Implementing Position Sensors for Hazardous Areas & Safety

DesignFast

Component Selection Made Simple.

Try it Today
design fast globle

Footer

EE WORLD ONLINE NETWORK

  • 5G Technology World
  • EE World Online
  • Engineers Garage
  • Analog IC Tips
  • Battery Power Tips
  • Connector Tips
  • DesignFast
  • EDA Board Forums
  • Electro Tech Online Forums
  • EV Engineering
  • Microcontroller Tips
  • Power Electronic Tips
  • Test and Measurement Tips

SENSOR TIPS

  • Subscribe to our newsletter
  • Advertise with us
  • Contact us
  • About us

Copyright © 2025 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy