What's the meaning of ''uncalibrated camera'' and ''calibrated camera''

In some structure from motion literature, we often encounter two terminologies 'calibrated camera' and 'uncalibrated camera'. So my question is what is the meaning of these two terms? My understanding is that 'calibrated camera’ means we already know the camera calibration parameters like the focal length , principle point and distortion coefficients, which can be used in the following SfM procedures. On the other hand, an ‘uncalibrated camera’ means that we don’t know the camera calibration parameters? Is my understanding correct? Or do you have additional explanations for these two terms, so that I can gain deeper understanding of these terminologies?

Answer 1

[Julia Antoniou]

Hi Xiaolong,

When you calibrate a camera, you are estimating parameters like the ones you mentioned in your question. These parameters can then be used to do some sort of image processing, like correcting lens distortion, measuring the size of an object, or determining a camera's location in a scene.

For an uncalibrated camera, these parameters have not been estimated, and therefore this kind of image processing cannot be done.

See the documentation page linked below for a more in-depth description of camera calibration. https://www.mathworks.com/help/vision/ug/camera-calibration.html

[Muhammad Abu Bakar]

I have a question from your answer. You told about measuring the size of the object. How can we measure the size of the object. ? Please. Can you explain?

[Cheng-Ta Shen]

In dual camera case, given the baseline, focal length, relationship between cameras, it is possible to derive the size of the object.