The docs here
http://devdocs.magento.com/guides/v2.1/frontend-dev-guide/themes/theme-images.html
clearly state "This command has no arguments or options."
Yet
E:\www\magento\www.example.com>php bin\magento catalog:images:resize Required parameter 'theme_dir' was not passed
How can I tell it the theme_dir it seems to be asking for?
Running into the same issue
It has been answered on stack Exchange:
https://magento.stackexchange.com/questions/100011/required-parameter-theme-dir-was-not-passed
Also my personal experience of this error was due to a registered theme no longer existing in the file system. In other words, I made a typing mistake in the theme's registration.php file. Deleting the non-existing/phantom/ghost theme eliminated the error.
The cause can be removed theme but you just remove directory not data in table theme. Please find unused them in table theme and remove it.
You can reference here for more detail.