Worldview 3 : Evaluation of its mineral mapping capability at Rodalquilar, Spain

Active interest by the exploration industry with multi-spectral VNIR-SWIR WorldView-3 (WV-3) imagery has been evident since its launch in August, 2014. Pre-launch simulation studies by Kruse and Perry (2013) and later comparison between resampled AVIRIS and WV-3 by Kruse et al. (2015) demonstrated its mineral mapping potential, using the well published hydrothermal test site at Cuprite, Nevada. Subsequent validation studies by Sun et al. (2017) tested WV-3 for its alteration discriminating within the Pobei area, Xinjiang Uygur, NW China. In this same area, Ye et al. (2017) also undertook a validation WV-3 study using 1:100,000 geological mapping and comparisons with ASTER. Neither study at Pobei undertook field sample spectroscopy. In this current validation study using the Rodalquilar epithermal setting in Spain, WV-3 mineral mapping results were compared with those obtained using resampled HyMap and ASTER imagery. In addition, WV-3 derived spectral signatures were compared with ASD spectrometer field observations of various homogeneous ground sites collected simultaneously with the WV-3 acquisition. Comparison between the WV-3, HyMap, ASTER map products were generated using Cudahy (2012) and Sun et al. (2017) band parameter indices for mineral(group)s including kaolinite, AlOH, MgOH, ferrous iron content in MgOH/carbonate, and jarosite. Compositional results generated with ASTER appeared to be noisy and less intense within the Rodalquilar study area. By comparison, Worldview-3 showed spatially coherent patterns and extents that were more comparable with the lithologies and alteration zonation’s published previously by Arribas et al. (1995). Overall, the results show that the combined WV-3 VNIR- SWIR image spatial resolution of 7.5m showed improved discrimination than those derived from equivalent ASTER’s spatial resolution of 30m. Compositional products derived from band parameters designed by Cudahy (2012) generally also gave better results than those from Sun et al (2017) at Rodalquilar. Comparison of the WV-3 surface reflectance product and the field spectral signatures showed a close resemblance for the exposed homogeneous car park targets when using a series of multiple transect grid like observations. Other field observations of various beaches, limestone outcrop exposures and mine-site spoil piles were also examined. Ongoing postgraduate Masters studies are currently being undertaken studying such target ASD spectral field observations and comparisons with the results from variable atmospheric processing and modelling of the WV-3 radiance imagery.