Abstract
Abstract. In this paper we propose new models of two complementary optical sensors to obtain 2.5-D measurements of opaque surfaces: a deflectometric and a plenoptic sensor. The deflectometric sensor uses active triangulation and works best on specular surfaces, while the plenoptic sensor uses passive triangulation and works best on textured, diffusely reflecting surfaces. We propose models to describe the measurement uncertainties of the sensors for specularly to diffusely reflecting surfaces under consideration of typical disturbances like ambient light or vibration. The predicted measurement uncertainties of both sensors can be used to obtain optimized measurements uncertainties for varying surface properties on the basis of a combined sensor system. The models are validated exemplarily based on real measurements.
Highlights
Automated quality inspection of product surfaces requires a fast and robust sensor, capable of detecting all relevant defects without damaging the surface
We propose uncertainty models for plenoptic and deflectometric sensors, and based on the models we simulate both sensors under similar circumstances on varying partially specular surfaces
In general any industrial camera can be transformed into a plenoptic camera by placing a micro lens array (MLA) in front of the image sensor
Summary
Automated quality inspection of product surfaces requires a fast and robust sensor, capable of detecting all relevant defects without damaging the surface. Optical measurement techniques fulfill these requirements but are highly dependent on the surface properties. Pattern projection and passive stereoscopic methods require diffuse reflectance, while deflectometric methods depend on specular reflectance of the inspected surface. Many surfaces are partially specular or a mixture of diffusely and specularly reflecting parts and cannot be robustly measured with only one method. By combining several measurement methods into a single sensor system that adapts its algorithms to exploit the advantages of the single methods, we are capable of measuring surfaces with a large variety of surface properties. We propose uncertainty models for plenoptic and deflectometric sensors, and based on the models we simulate both sensors under similar circumstances on varying partially specular surfaces
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