> > When you are doing the calibration do you also compute the focal > > value? > Do you mean focal distance or focal length? > focal length
> Or do you use directly the metadata information and only compute > > the distortion? > I use from the metadata the camera model (sensor size), lens model, > and the focal length. > Ok, in that case, it makes sense! The focus has an impact on the focal length. I guess that the metadata from the camera doesn't take the focus into account. On the camera device, it's just a mechanical record of the focal length choose by the user on the device. The theoretical focal length value matches the real focal length of the lens/camera device when the focus is at infinity. So if you use the focal length from the metadata and the focus is not at infinity, you are using a wrong focal length. If we use a checkerboard for calibration, we compute both the focal length and the distortion, so the result will be correct because this relationship is independent from the focus. So if we add a checkerboard calibration, it will have the same behavior than currently. Are you interested if we propose a pull request with a new calibration binary (with OpenCV optional at compile time)? We can provide images with checkerboards and buildings to allow you to compare/evaluate this solution with the existing one. Best regards, Fabien
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