[opencv bug] orb flannBaseMatcher Exception

when i use flannBaseMathcer to match 2 sets of orb descriptor, it occured an exception : unsigned long exception.

http://blog.csdn.net/holybin/article/details/40926315

this blog says that orb descriptior has a type of uchar, but flannMatcher doesn‘t support a uchar matcher like orb or brief.

so I used  the BFMatcher and the exception vanished!