Для openSUSE Tumbleweed запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/KDE:Qt:5.12/openSUSE_Tumbleweed/KDE:Qt:5.12.repo
zypper refresh
zypper install opencv
Для openSUSE Leap 15.2 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/KDE:Qt:5.12/openSUSE_Leap_15.2/KDE:Qt:5.12.repo
zypper refresh
zypper install opencv
Для openSUSE Leap 15.1 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/KDE:Qt:5.12/openSUSE_Leap_15.1/KDE:Qt:5.12.repo
zypper refresh
zypper install opencv
Для openSUSE Leap 15.0 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/KDE:Qt:5.12/openSUSE_Leap_15.0/KDE:Qt:5.12.repo
zypper refresh
zypper install opencv