  This article presents a new optical measurement method employing a HSI (Hue,
Saturation and Intensity) colour model to form trapezoidal structured patterns
for morphology reconstruction of a measured object at a high speed.
Profilometry on objects having non-monochromatic surfaces is considered as one
of the remaining most challenges faced by the currently existing
structured-light projection methods since the surface reflectivity to red,
green and blue light may vary significantly. To address this, an innovative
colour calibration method for hue component is developed to determine the
accurate reflectivity response of the measured surface. The trapezoidal colour
pattern is calibrated to compensate the hue-shifted quantity induced by the
reflective characteristics of the object's surface. The developed method can
reconstruct precise 3-D surface models from objects by acquiring a single-shot
image, which can achieve high-speed profilometry and avoid in-situ potential
measurement disturbances such as environmental vibration. To verify the
feasibility of the developed methodology, some experiments were conducted to
confirm that the measurement accuracy can be controlled within 2.5% of the
overall measurement range and the repeatability of 3.0% within +/- 3*sigma can
be achieved.
