Disclosed herein are systems, methods, and structures providing accurate and easy to use size measurement of physiological features identified from endoscopic examination. In sharp contrast to the prior art, systems, methods, and structures according to the present disclosure employ structured light that advantageously enables size and/or distance information about lesions and/or other physiological features in a gastrointestinal (GI) tract. Advantageously, systems, methods, and structures according to the present disclosure are applicable to both capsule endoscopes and insertion endoscopes.