How can I calibrate the camera and make sure the measurement is accurate?

V-STARS normally automatically calibrates the camera as a byproduct of the measurement in a process called self-calibration. Self-calibration is a very powerful technique that allows the camera to be calibrated at the time of measurement under the conditions that exist at the time of the measurement. In order to self-calibrate the camera you must take a minimum of six photographs if the object is essentially flat, and a minimum of four photographs if the object isn’t flat. If self-calibration can’t be used on a particular measurement, pre-calibrated values can be used but accuracies may be somewhat lower. See Self-Calibration for more details.

V-STARS also provides internal estimates of accuracy for each measured point. These internal estimates of accuracy have been extensively compared to external measures of accuracy (repeatability, artifacts, known distances, measurements by other systems, etc.) and have been found to be consistent and reliable. This is important because often in everyday measurements one does not have access to external measures of accuracy and must rely on the internal accuracy estimate as a quality indicator.

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