Hi Ainur,
Do you mean taking a screenshot? normally pushing volume and power buttons at the same time takes a screenshot.
For an Orthogonal view, it is not possible with the current App. You may export the texture mesh and open it on MeshLab on a Desktop computer. In Mesh lab it is possible to adjust the field of view (to get orthogonal view). Do Shift+mouse wheel to change FOV (at 0 degrees you get orthogonal view). I added an issue to add this feature directly in the app:
https://github.com/introlab/rtabmap/issues/193cheers,
Mathieu