3D Reconstruction with uncalibrated cameras

I'm working on my degree thesis, regarding Dense Stereo 3D Reconstruction.

As of now, I've written a GUI that lets the user select two images (left and right stereo pair) and rectify them by manually inserting corresponding points. Since I'm working with very old stereo photos, I don't know anything about the camera specs, and I have to assume that the photographer used different cameras during his work. This means that the Rectifying algorithm I used is an uncalibrated one.

The rectified images are then used to calculate a disparity map using OpenCV stereoBM (or different algorithms).

Now, I need to find a way to reconstruct a 3D scene using the disparity map I got. I don't think I can use reconstructScene, because, as I've said, I have no camera parameters.

Do you guys have any advice on what to do?

Thanks in advance for your answers.

[Matt J]

Do you have any additional information in the scene, e.g., parallel lines, parallel planes, etc...?

[Giulio Bassetti]

The photos represent Florence (Italy) in the late 1800. As they're really old, the quality isn't that great, but I think I can get some additional information (such as parallel lines) from the buildings in the pictures.