Validation of in-water 3D radiative transfer using DIRSIG

Abstract

Sensor reaching radiance in coastal ocean-water environments contains contributions from the air-water interface, in-water objects, and the participating volume itself. If rendered by a forward-modeling synthetic image generation program, the imagery must account for several interesting phenomenon, including, but not limited to; volumetric scattering, shadows, skyfraction, background reflections, and capillary and gravity wave glints and caustics. DIRSIG models the radiative transfer process in this complex environment using a combination of sophisticated raytracing and photon mapping techniques. This research illustrates a subset of our validation efforts associated with the forward radiometric modeling process used by DIRSIG when rendering coastal environments with significant contributions from in-water objects. The results exemplify DIRSIG's ability to render spectrally independent (elastic) and radiometrically accurate hyperspectral imagery of participating media.

Advances in simulating radiance signatures for dynamic air/water interfaces

“…2,3 The approach taken was intended to be as flexible as possible in handling three-dimensional inhomogeneities, rather than using the plane-parallel assumptions underlying more established and efficient codes. 4 This was accomplished by using a bidirectional Monte Carlo technique referred to as "photon mapping," that connects source contributions to sensor samples (rays) via a local flux density estimate that could adapt to any in-water conditions.…”