How Reconstruction tools works? i have this scene tracked. The "camera solve error" appear to be not bad (0.5).

My question is: How the "reconstruction tools" works?

To set the FLOOR it ask only two trackers when normally we need minimum 3 points to have a plane. To set an AXIS it ask only one tracker when from what i know we need minimum 2 points to have a line. In fact, when i try to define one axis in the tracked scene selecting one tracker it changes anytime the result without an apparent logic behind. Now in this scene the trackers are moving nice and following their spots in a good way but the final perspective of the camera is not good as you can see.

(The settings of camera and lens are correct.)

I apologize for my bad English.
Dont use the reconstruction tool for that type of tracking, use the solve camera motion. Then use one tracker as a origin, three trackers as a plane and two as axis.