Why is the numerator X - b and not b - X? It seems the length of the top part of the red triangle is the length of the baseline minus the length X, which was the horizontal distance between the point $X$ and the first camera center O.
motoole2
The 3D point $X$ at a position $X-b$ with respect to the right camera. (Note that $X-b$ is a negative quantity here; if you simply care about length, then you can take its absolute value $|X-b|$.)
nssampat
If we're setting the right camera $O'$ as the origin then $O$ is at -b. Then the point $X$ would be at $-b + X$ or $X-b$ as you said. However, using this coordinate system, we have that the point $x'$ is located at $-x'$ since it is also to the left of the origin $O'$. Then there is a mismatch between the signs of the numerators. What's wrong with my logic here?
motoole2
The problem here is that the statement "the point $x'$ is located at $-x'$" is incorrect. The point $x'$ is located at $x'$. :-) The point $x'$ simply has negative value.
Why is the numerator X - b and not b - X? It seems the length of the top part of the red triangle is the length of the baseline minus the length X, which was the horizontal distance between the point $X$ and the first camera center O.
The 3D point $X$ at a position $X-b$ with respect to the right camera. (Note that $X-b$ is a negative quantity here; if you simply care about length, then you can take its absolute value $|X-b|$.)
If we're setting the right camera $O'$ as the origin then $O$ is at -b. Then the point $X$ would be at $-b + X$ or $X-b$ as you said. However, using this coordinate system, we have that the point $x'$ is located at $-x'$ since it is also to the left of the origin $O'$. Then there is a mismatch between the signs of the numerators. What's wrong with my logic here?
The problem here is that the statement "the point $x'$ is located at $-x'$" is incorrect. The point $x'$ is located at $x'$. :-) The point $x'$ simply has negative value.