Overview of Active Research


My research is about simulating on a computer the physics of light propagation as it happens in real-world scenarios and environments. Light is electromagnetic energy that propagates through space, interacts with media and matter (for example, light scatters off a surface or passes through a glass of water), and, at some point, may be sensed by a detector, like the human eye or a camera. This entire process, beginning with the sourcing of this light energy from a light source, till the detection by an observer is known as light transport. Simulating such light transport efficiently, but in a physically-accurate fashion, is the centre of my study.

Motivation

"In our time of ever-increasing specialization, there is a tendency to concern ourselves with relatively narrow scientific problems. The broad foundations of our present-day scientific knowledge and its historical development tend to be forgotten too often. This is an unfortunate trend, not only because our horizon becomes rather limited and our perspective somewhat distorted, but also because there are many valuable lessons to be learned in looking back over the years during which the basic concepts and the fundamental laws of a particular scientific discipline were first formulate."
Emil Wolf

In modern rendering light transport is formulated under radiometry – a scientific field that deals with measuring electromagnetic radiation. The basic quantities in radiometry have units of power, and indeed our sensors that observe light measure the radiation’s power per unit area. However, such a description of light ignores the light’s wave-nature and treats light energy as packets that travel along straight lines, i.e. a simplified optical formalism commonly known as “ray-optics” (or “geometric-optics”). To simulate the propagation of light – under that radiometric formalism – a family of numerical algorithms known as path tracing have emerged over the last few decades. Path tracing are Monte-Carlo integration algorithms designed to solve the light transport problem in complicated scenes that model real-world environments. These techniques have been proven tremendously successful: Virtually all the computer generated content you see in modern movies these days have been rendered using path tracing methods.

Nevertheless, the wave-nature of light plays a crucial role in a variety of optical phenomena: for example, the colourful appearance of scratches in a metal surface, butterfly wings, oil on water and soap bubbles and the diffraction grating of compact disks and LCD screens. It is also noteworthy that these diffraction effects become more pronounced when dealing with electromagnetic waves of non-optical frequencies (e.g., radar or WiFi), because these waves are typically of significantly longer wavelength compared to visible light. Thus, if we would like to account for these phenomena the wave-nature of light can not be ignored, and the simulation of light behaviour needs to be done using a more physical description of light.

My goal is then to bridge the gap between the realms of rendering and physical optics and develop a general framework of light transport that remains consistent with electromagnetism (EM) and is applicable to scenarios where traditional optical tools are intractable: complicated environments.

Applications

Applications of such work are not limited to photorealistic rendering, in addition I would like to investigate applications in the areas of:

  • Study of non-optical wave propagation (e.g., radar, cellular or WiFi signals) in urban environments.
  • Optical coherence tomography in complex scenes.
  • Non-optical imaging.
  • Non-line-of-sight imaging with partially-coherent light.
  • Computational electrodynamics in complicated environments.

That is, where there is value in accurately simulating the propagation of EM waves in settings that are too complicated for traditional wave solvers.


This page is a work in progress