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robobo-programming / camera-calibration

Camera calibration: tips and tricks

To achieve a good calibration result the object to calibrate should be adjusted to match the circle on the screen, as in the following image:

Good calibration position

When a good calibration is obtained, the preview window should be like the next image, a well defined silhoutte with no noise. The color of the image doesn't always match the object color, as only the high range of the calibrated color is displayed.

Good calibration position example

Common mistakes

In the next section the most common bad calibrating habits are shown.

Too close to the camera

Some practices must be avoided to get a good result. The most common mistake is holding the object too close to the camera, this results on only a small area of the object being captured.

Too close calibration position

This kind of mistake produces this type of segmented images, because of the narrow color range not all the parts of the object are recognized

Too close calibration position example

Too far from the camera

If the object is hold too far from the camera the backgrond could be captured, this practice produces very bad calibration, as all the background can be potentially detected as the object.

Too far calibration position

In the next image we can see the results of this calibration.

Too far calibration position example

#### The object is to brilliant ####

If the object that we want to calibrate is too brilliant, there might be reflections of the colors in the surroundings.

Too close calibration position

In the next image this effect is cleartly visible, as part of the hand, which gets the reflection, is detected as the object.

Too close calibration position example