If you really want to use RViz plugins for this (as I'm not entirely sure it's supposed to be used like this), I'd recommend:
- to render arbitrary points of view: use lucasw/rviz_camera_stream: it's an RViz plugin, so you can just add it to your RViz configuration
- to control the camera (focus, zoom level, fov): look at AIS-Bonn/rviz_cinematographer. From the documentation: An rqt plugin to create and edit trajectories for the rviz camera and record its views in a video.
And a comment:
I'm trying to make an AR-Application.
I'd take a look at how previous implementations, such as ros-visualization/oculus_rviz_plugins (forks are more up-to-date), AndreGilerson/rviz_vive, ROSIN FTP: rvis2ar, IntelligentRoboticsLabs/ARViz and others have approached this.
Or perhaps even reuse some of them.
For an AR application it may be more efficient to directly alter the way RViz renders the scene.
It's based on OGRE, so anything is possible.