or with batch rendering

* Fixed type narrowing issues

This built correctly before because tests were run with the highgui module enabled.
The sfm module links against the features2d module, which brings in the highgui module as an optional target if enabled.
Through this path, imread was working correctly despite the file including the wrong header and not declaring its linking dependency.

Expose line descriptor python (#1994)

* Created wrappers for other line_descriptor functions/classes

* Changes to expose LSD and EDLines params in Python and make line descriptor available in Python

* Fix spelling of perpectiveRemovePixelPerCell in struct docstring

* Fix spelling of perpectiveRemovePixelPerCell in detection tutorial

Resolves #1963

so meshes in any orientation can be properly viewed

* fbs_filter add lambda & revise imtypes

* fix warnings

* fix fbs function prototypes

Hey there, completely new to `openCV` in general and to the `bioinspired` module in particular. I wanted to give this module a try with python and found that the example source code doesn't work with current openCV (that's 3.4.1 on my Fedora machine).  Apparently, there was a change in how a `Retina` object is created. I fixed the python source code correspondingly. I also changed the C++ source code in this doc file, although I think this needs further updating as there are more changes in the actual source code.

* add fast bilateral solver from master

* fix unused variables warnings in disparity_filtering.cpp

* trailing whitespaces removed

  * loosen the threshold in Rgbd_Normals.compute
  * make the minimum tvec larger in RGBD_Odometry_Rgbd.algorithmic