Practical and Accurate Reconstruction of an Illuminant's Spectral Power Distribution for Inverse Rendering Pipelines

TL;DR

A simple, low-cost technique to capture and reconstruct the SPD of uniform illuminants of uniform illuminants using a diffractive compact disk and a machine learning approach for accurate estimation is presented.

Abstract

Inverse rendering pipelines are gaining prominence in realizing photo-realistic reconstruction of real-world objects for emulating them in virtual reality scenes. Apart from material reflectances, spectral rendering and in-scene illuminants' spectral power distributions (SPDs) play important roles in producing photo-realistic images. We present a simple, low-cost technique to capture and reconstruct the SPD of uniform illuminants. Instead of requiring a costly spectrometer for such measurements, our method uses a diffractive compact disk (CD-ROM) and a machine learning approach for accurate estimation. We show our method to work well with spotlights under simulations and few real-world examples. Presented results clearly demonstrate the reliability of our approach through quantitative and qualitative evaluations, especially in spectral rendering of iridescent materials.

Figures (2)

• Figure 1: (a) Real World CD Capture setup with Canon Rebel T8i (b)With few adjustments of CD or illumination the rings were captured with the SPD shown in (c) measured with Hoppoocolor OHSP350 .
• Figure 2: Two more examples in SPD reconstruction and the impact on rendering accuracy. Rendering PSNR for top = 46.596 dB and for the bottom = 55.352 dB