[35.2.1][35.3.1]["20.04"] Nvidia packages for OpenCV not compatible with focal

[bmegli]

Nvidia forums:

• https://forums.developer.nvidia.com/t/jetpack-5-opencv-version-nvidia-should-stick-to-ubuntu-standards/218637

Problem:

• Nvidia installs own OpenCV version with Jetpack at 4.5.
• this is only OpenCV and not OpenCV contrib package which comes from focal ppa at 4.2.
• this brings conflicts in package manager/prevents LTS software dependent on OpenCV contrib package to install

[bmegli]

OpenCV focal packages are available on Jetson (by default)

To switch to them you need to remove Nvidia's package (different naming) and install focal versions.

[bmegli]

Workaround

Warnings:

• doing below will mark packages dependent on OpenCV for removal!
  • ideally this should be combined in single instruction to prevent side effect
• Nvidia's OpenCV is newer version
  • side effects are possible if you use software that depends explicitly on newer version

# this is Nvidia's package
sudo apt remove libopencv
# those are Focal LTS packages
sudo apt install libopencv-core4.2
sudo apt install libopencv-dev=4.2.0+dfsg-5
sudo apt install libopencv-contrib-dev

# prevent system reinstalling Nvidia's version on upgrade (pin Focal variant)
sudo apt-mark hold libopencv-dev libopencv-core4.2

[bmegli]

Some software affected by Nvidia's OpenCV variant:

• ROS