Automated spectro-goniometer: A spherical robot for the field measurement of the directional reflectance of snow

We describe an automated spectro-goniometer (ASG) that rapidly measures the spectral hemispherical-directional reflectance factor (HDRF) of snow in the field across the wavelength range 0.4⩽λ⩽2.5 μm. Few measurements of snow’s HDRF exist in the literature, in part caused by a lack of a portable instrument capable of rapid, repeatable sampling. The ASG is a two-link spherical robot coupled to a field spectroradiometer. The ASG is the first revolute joint and first automated field goniometer for use over snow and other smooth surfaces. It is light enough (∼50 kg) to be portable in a sled by an individual. The ASG samples the HDRF at arbitrary angular resolution and 0.5 Hz sampling rate. The arm attaches to the fixed-point frame 0.65 m above the surface. With vertical and oblique axes, the ASG places the sensor of the field spectroradiometer at any point on the hemisphere above a snow target. In standard usage, the ASG has the sun as the illumination source to facilitate in situ measurements over fragile sur...

[1]  D. L. Macadam.  Color Measurement: Theme and Variations , 1981 .

[2]  Stephen G. Warren,et al.  Optical Properties of Snow , 1982 .

[3]  D. Deering,et al.  A sphere-scanning radiometer for rapid directional measurements of sky and ground radiance: The PARABOLA field instrument , 1984 .

[4]  R. Barry,et al.  Large scale effects of seasonal snow cover , 1987 .

[5]  J. Dozier,et al.  The spectral bidirectional reflectance of snow , 1988 .

[6]  K. Stamnes,et al.  Numerically stable algorithm for discrete-ordinate-method radiative transfer in multiple scattering and emitting layered media. , 1988, Applied optics.

[7]  S. Warren,et al.  Reflection of solar radiation by the Antarctic snow surface at ultraviolet, visible, and near‐infrared wavelengths , 1994 .

[8]  S. Sandmeier,et al.  Sensitivity analysis and quality assessment of laboratory BRDF data , 1998 .

[9]  Jean Luc Deuze,et al.  Ground measurements of the polarized bidirectional reflectance of snow in the near‐infrared spectral domain: Comparisons with model results , 1998 .

[10]  Jacqueline Lenoble,et al.  A MODEL FOR THE BIDIRECTIONAL POLARIZED REFLECTANCE OF SNOW , 1999 .

[11]  James J. Simpson,et al.  Bidirectional anisotropic reflectance of snow and sea ice in AVHRR Channel 1 and 2 spectral regions. I. Theoretical analysis , 1999, IEEE Trans. Geosci. Remote. Sens..

[12]  Klaus I. Itten,et al.  A field goniometer system (FIGOS) for acquisition of hyperspectral BRDF data , 1999, IEEE Trans. Geosci. Remote. Sens..

[13]  L. W. Tsai,et al.  Robot Analysis: The Mechanics of Serial and Parallel Ma-nipulators , 1999 .

[14]  Michael I. Mishchenko,et al.  Bidirectional Reflectance of Flat, Optically Thick Particulate Layers: An Efficient Radiative Transfer Solution and Applications to Snow and Soil Surfaces , 1999 .

[15]  Teruo Aoki,et al.  Effects of snow physical parameters on spectral albedo and bidirectional reflectance of snow surface , 2000 .

[16]  J. Conel,et al.  PARABOLA III: A sphere‐scanning radiometer for field determination of surface anisotropic reflectance functions , 2000 .

[17]  Carol J. Bruegge,et al.  A Spectralon BRF data base for MISR calibration applications , 2001 .

[18]  T. Painter,et al.  Retrieval of subpixel snow-covered area and grain size from imaging spectrometer data , 2003 .

[19]  A. Karimi,et al.  Master‟s thesis , 2011 .