How to Determine X Rotation Angle of a Plane from Pictures?

[RavenAll]

Hi all.

I need to get some information about plane position and camera position from a pictures.
I have i plane with 3 points (red,green,blue) and then theyre coordinates inside the image.
Using circle and string i was able to get the y rotation of the plane where the points are on (the rotation of point of view)
But now i need the x rotation of the plane (the up/down angle that the camera taken the picture).
But I'm not able to find a way to get it.

This is an image of the angle i need
http://img408.imageshack.us/i/dim01.jpg/

For example this image have a x angle of around 90° (top view)
http://img41.imageshack.us/i/dscf0179a.jpg/

While this have an x angle of around 30°
http://img222.imageshack.us/i/dscf0177n.jpg/


Any ideas?

Thanks.


Ps:the 3 points on the plane are disposed as a regular triangle.

 

[pat_connell]

If you have the coordinates of each point on the plane, you can use basic trigonometry to calculate the angle of rotation of the camera. You can use the Law of Cosines to calculate the angle between two points. Then you can calculate the angle of the camera using the angles of the triangle formed by the three points.