DeLight-Net: Decomposing Reflectance Maps into Specular Materials and Natural Illumination

In this paper we are extracting surface reflectance and natural environmental illumination from a reflectance map, i.e. from a single 2D image of a sphere of one material under one illumination. This is a notoriously difficult problem, yet key to various re-rendering applications. With the recent advances in estimating reflectance maps from 2D images their further decomposition has become increasingly relevant. To this end, we propose a Convolutional Neural Network (CNN) architecture to reconstruct both material parameters (i.e. Phong) as well as illumination (i.e. high-resolution spherical illumination maps), that is solely trained on synthetic data. We demonstrate that decomposition of synthetic as well as real photographs of reflectance maps, both in High Dynamic Range (HDR), and, for the first time, on Low Dynamic Range (LDR) as well. Results are compared to previous approaches quantitatively as well as qualitatively in terms of re-renderings where illumination, material, view or shape are changed.Comment: Stamatios Georgoulis and Konstantinos Rematas contributed equally to this wor

A Dual-Beam Method-of-Images 3D Searchlight BSSRDF

We present a novel BSSRDF for rendering translucent materials. Angular effects lacking in previous BSSRDF models are incorporated by using a dual-beam formulation. We employ a Placzek's Lemma interpretation of the method of images and discard diffusion theory. Instead, we derive a plane-parallel transformation of the BSSRDF to form the associated BRDF and optimize the image confiurations such that the BRDF is close to the known analytic solutions for the associated albedo problem. This ensures reciprocity, accurate colors, and provides an automatic level-of-detail transition for translucent objects that appear at various distances in an image. Despite optimizing the subsurface fluence in a plane-parallel setting, we find that this also leads to fairly accurate fluence distributions throughout the volume in the original 3D searchlight problem. Our method-of-images modifications can also improve the accuracy of previous BSSRDFs.Comment: added clarifying text and 1 figure to illustrate the metho

Fundamental remote sensing science research program. Part 1: Status report of the mathematical pattern recognition and image analysis project

The Mathematical Pattern Recognition and Image Analysis (MPRIA) Project is concerned with basic research problems related to the study of the Earth from remotely sensed measurement of its surface characteristics. The program goal is to better understand how to analyze the digital image that represents the spatial, spectral, and temporal arrangement of these measurements for purposing of making selected inference about the Earth

Earthshine as an Illumination Source at the Moon

Earthshine is the dominant source of natural illumination on the surface of the Moon during lunar night, and at locations within permanently shadowed regions that never receive direct sunlight. As such, earthshine may enable the exploration of areas of the Moon that are hidden from solar illumination. The heat flux from earthshine may also influence the transport and cold trapping of volatiles present in the very coldest areas. In this study, Earth's spectral radiance at the Moon is examined using a suite of Earth spectral models created using the Virtual Planetary Laboratory (VPL) three dimensional modeling capability. At the Moon, the broadband, hemispherical irradiance from Earth near 0 phase is approximately 0.15 watts per square meter, with comparable contributions from solar reflectance and thermal emission. Over the simulation timeframe, spanning two lunations, Earth's thermal irradiance changes less than a few mW per square meter as a result of cloud variability and the south-to-north motion of sub-observer position. In solar band, Earth's diurnally averaged light curve at phase angles < 60 degrees is well fit using a Henyey Greenstein integral phase function. At wavelengths > 0.7 microns, near the well known vegetation "red edge", Earth's reflected solar radiance shows significant diurnal modulation as a result of the longitudinal asymmetry in projected landmass, as well as from the distribution of clouds. A simple formulation with adjustable coefficients is presented for estimating Earth's hemispherical irradiance at the Moon as a function of wavelength, phase angle and sub-observer coordinates. It is demonstrated that earthshine is sufficiently bright to serve as a natural illumination source for optical measurements from the lunar surface.Comment: 27 pages, 15 figures, 1 tabl