ARGon3: “3D appearance robot-based gonioreflectometer” at PTB

Abstract

At the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany, a new facility for measuring visual appearance-related quantities has been built up. The acronym ARGon(3) stands for "3D appearance robot-based gonioreflectometer". Compared to standard gonioreflectometers, there are two main new features within this setup. First, a photometric luminance camera with a spatial resolution of 28 μm on the device under test (DUT) enables spatially high-resolved measurements of luminance and color coordinates. Second, a line-scan CCD-camera mounted to a spectrometer provides measurements of the radiance factor, respectively the bidirectional reflectance distribution function, in full V(λ)-range (360 nm-830 nm) with arbitrary angles of irradiation and detection relative to the surface normal, on a time scale of about 2 min. First goniometric measurements of diffuse reflection within 3D-space above the DUT with subsequent colorimetric representation of the obtained data of special effect pigments based on the interference effect are presented.

BRDF Slices: Accurate Adaptive Anisotropic Appearance Acquisition

“…The first is based on gonioreflectometers where all combinations of illumination and viewing directions are achieved by the sequential mutual positioning of light, sensor, and sample [7,8]. The second category leverages mechanical complexity using parabolic mirrors to capture multiple views in a single image [1,4].…”

Using a Robotic Arm for Measuring BRDFs

“…Several precise, robot-based gonioreflectometers exist today [5,1,16,4,15,8]. At Physikalisch-Technische Bundesanstalt (PTB), for example, they have developed a robot-based gonioreflectometer with a five-axis robot holding the sample and a homogeneous sphere radiator mounted on a ring-shaped rotation stage for illumination [5,4]. This system relies on calibrated incident radiance and is generally comprised of more purpose-built components than our setup.…”

Rapid determination of the photometric bidirectional scatter distribution function by use of a near-field goniophotometer

“…Additional baffles are introduced to reduce stray light. If necessary, a colored glass filter with a dedicated interference coating can be introduced to produce, in combination with the tungsten halogen lamp, a good representation of a D65 illuminant 6 . The total distance of the illumination system is limited to 0.60 m, such that the goniometer is able to freely rotate in space without being obstructed.…”

“…computer graphics 2-3 , remote sensing [4][5] , appearance characterization [6][7] and lighting design [8][9] . In result, many BRDF and BTDF measuring instruments *Frederic.leloup@kuleuven.be; phone +32 9 265.87.13; fax +32 9 225.62.69; www.lichttechnologie.be have been reported in the literature 10 .…”