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Laser Detection#

Authors: Holoscan Team (NVIDIA)
Supported platforms: aarch64
Language: Python
Last modified: May 13, 2025
Latest version: 1.0
Minimum Holoscan SDK version: 2.1.0
Tested Holoscan SDK versions: 2.2.0
Contribution metric: Level 1 - Highly Reliable

Overview#

This application demonstrates the latency differences between USB and EVT cameras by detecting laser pointer positions on a monitor. It uses two camera sources to track laser positions and displays the results in real-time with different colored icons.

Hardware Requirements#

  • USB camera (Logitech 4k Pro Webcam or compatible)
  • EVT camera (HB-9000-G 25GE or compatible)
  • Monitor with matte screen (120fps or higher refresh rate recommended)
  • Safe laser pointer for viewing purposes
  • Completed calibration files from both USB and EVT calibration apps

Setup Instructions#

  1. Complete the calibration process for both USB and EVT cameras
  2. Ensure both cameras are properly connected and configured
  3. Position the cameras to have a clear view of the monitor
  4. Verify the calibration files (usb-cali.npy and evt-cali.npy) are present in the build directory

Running the Application#

./run build laser_detection
sudo LD_PRELOAD=/usr/lib/aarch64-linux-gnu/nvidia/libnvjpeg.so ./run launch laser_detection

Usage#

  • A white icon represents the USB camera's laser detection
  • A green icon represents the EVT camera's laser detection
  • Point the laser at the monitor to see the latency difference between the two cameras
  • The icons will move to the coordinates where the laser is detected

Notes#

  • Use only a matte screen monitor to avoid specular reflections
  • Ensure proper lighting conditions
  • Use only safe laser pointers designed for viewing purposes
  • If detection is inaccurate, recalibrate both cameras
  • The application requires sudo privileges to run