# How to calculate point in 3D space from multiple perspective

I have multiple camera in different points.

I have their position and rotation as $$(x,y,z)$$ , $$(\alpha,\beta,\gamma)$$ or $$( roll, pitch, yaw)$$ .

And I have output like this :

Feed from camera-1, I know length of yellow and green.

How can I calculate position of the object, in this case head in 3D space.

So from a camera with position at $$(x_c, y_c, z_c)$$ and detecting the object in the pixel of direction defined by the unitary vector $$(x_d, y_d, z_d)$$, you know the object is along the direction:
($$x_c + x_d \times d, y_c + y_d \times d, z_c + z_d \times d$$) with $$d$$ being the distance camera-object.
• Imagine you have a 2°x2° camera with 200x200 pixels. The corners pixels observe a direction doing $\pm 1^o$ of pitch and $\pm 1^o$ of yaw with respect to the center pixel. Jun 20 '19 at 14:41