I do downhole test using CCTV. Is there any open codes of the OpenCV I can use for a digital image stitching?

edit

optical inspection requires precision. otherwise you'll only get guesswork.

you can do SLAM but that's notoriously difficult on forward-moving cameras: no parallax in the center, very little near the edges where image usually becomes distorted and blurry.

you could fix your camera path, prevent it from tilting and jostling around, just one axis of movement (forward in the camera's frame). then you need to assume that the hole is round and the camera's axis is colinear with the hole's axis. then you have a chance of "scanning" that hole. transform camera picture to a cylindrical projection of the hole's wall. then you can try stitching consecutive pictures because the transformation between mapped pictures is just a translation (along the hole/pipe's length).