An end-to-end hyperspectral scene simulator with alternate adjacency effect models and its comparison with cameoSim

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dc.contributor.authorZahidi, Usman A.
dc.contributor.authorYuen, Peter W. T.
dc.contributor.authorPiper, Jonathan
dc.contributor.authorGodfree, Peter S.
dc.date.accessioned2020-04-24T11:29:30Z
dc.date.available2020-04-24T11:29:30Z
dc.date.issued2019-12-24
dc.description.abstractIn this research, we developed a new rendering-based end to end Hyperspectral scene simulator CHIMES (Cranfield Hyperspectral Image Modelling and Evaluation System), which generates nadir images of passively illuminated 3-D outdoor scenes in Visible, Near Infrared (NIR) and Short-Wave Infrared (SWIR) regions, ranging from 360 nm to 2520 nm. MODTRAN TM (MODerate resolution TRANsmission), is used to generate the sky-dome environment map which includes sun and sky radiance along with the polarisation effect of the sky due to Rayleigh scattering. Moreover, we perform path tracing and implement ray interaction with medium and volumetric backscattering at rendering time to model the adjacency effect. We propose two variants of adjacency models, the first one incorporates a single spectral albedo as the averaged background of the scene, this model is called the Background One-Spectra Adjacency Effect Model (BOAEM), which is a CameoSim like model created for performance comparison. The second model calculates background albedo from a pixel’s neighbourhood, whose size depends on the air volume between sensor and target, and differential air density up to sensor altitude. Average background reflectance of all neighbourhood pixel is computed at rendering time for estimating the total upwelled scattered radiance, by volumetric scattering. This model is termed the Texture-Spectra Incorporated Adjacency Effect Model (TIAEM). Moreover, for estimating the underlying atmospheric condition MODTRAN is run with varying aerosol optical thickness and its total ground reflected radiance (TGRR) is compared with TGRR of known in-scene material. The Goodness of fit is evaluated in each iteration, and MODTRAN’s output with the best fit is selected. We perform a tri-modal validation of simulators on a real hyperspectral scene by varying atmospheric condition, terrain surface models and proposed variants of adjacency models. We compared results of our model with Lockheed Martin’s well-established scene simulator CameoSim and acquired Ground Truth (GT) by Hyspex cameras. In clear-sky conditions, both models of CHIMES and CameoSim are in close agreement, however, in searched overcast conditions CHIMES BOAEM is shown to perform better than CameoSim in terms of ℓ1 -norm error of the whole scene with respect to GT. TIAEM produces better radiance shape and covariance of background statistics with respect to Ground Truth (GT), which is key to good target detection performance. We also report that the results of CameoSim have a many-fold higher error for the same scene when the flat surface terrain is replaced with a Digital Elevation Model (DEM) based rugged one.en_UK
dc.identifier.citationZahidi UA, Yuen PWT, Piper J, Godfree PS. (2020) An end-to-end hyperspectral scene simulator with alternate adjacency effect models and its comparison with cameoSim. Remote Sensing, Volume 12, Issue 1, December 2019, Article number 74en_UK
dc.identifier.issn2072-4292
dc.identifier.urihttps://doi.org/10.3390/rs12010074
dc.identifier.urihttp://dspace.lib.cranfield.ac.uk/handle/1826/15410
dc.language.isoenen_UK
dc.publisherMDPIen_UK
dc.rightsAttribution 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/*
dc.subjecthyperspectral scene simulationen_UK
dc.subjectadjacency-effecten_UK
dc.subjectcameoSimen_UK
dc.subjectatmosphere searchen_UK
dc.titleAn end-to-end hyperspectral scene simulator with alternate adjacency effect models and its comparison with cameoSimen_UK
dc.typeArticleen_UK

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