Reprojection error during localization

[messileonardo]

In the localization procedure, the user is asked to set the following parameter
'estimation': {'ransac': {'max_error': 12}}
that, if I am not wrong, is the maximum reprojection error in pixel. My question is, given the maximum reprojection error in pixel (i.e., a threshold with default value =12 pixels), where can I find the real reprojection error (that I expect to be under that threshold, i.e. 12 pixels)?
Many thanks in advance!