Gladimir V. G. Baranoski

• Professor (Full) at University of Waterloo

Early invasive skin melanoma (EISM) associated with partial tumor invasion to the thin and optically complex papillary dermis (PD) represents a critical stage before the onset of metastasis. EISM lesions may be accompanied by angiogenesis, which can alter the PD's blood and fibril contents. A comprehensive understanding about these interconnected p...

Variations in the productivity of subnivean vegetation can substantially affect the ecology of regions more susceptible to increasing warming levels and lead to significant feedback effects on the global climate. Due to its importance, this topic is at the center of a broad scope of interdisciplinary studies supported by field and remote sensing ob...

Material appearance is largely determined by complex light attenuation processes. The distinct bluish colorations that can be observed when light is transmitted through snow are among the most striking outcomes of these processes. In this article, we present a method for the predictive rendering of this phenomenon taking into account the variabilit...

The hyperspectral reflectance and transmittance of flowing blood samples are employed in a wide range of biomedical applied research initiatives such as the detection and monitoring of hematological abnormalities. The success of these initiatives is tied to the correct interpretation of these radiometric quantities. This, in turn, requires a compre...

Changes in skin appearance are among the most recognizable symptoms of a number of medical conditions. The interpretation of such changes, however, may be inadvertently biased by normal physiological processes affecting skin optical properties. In this paper, we assess the impact of one of the most common of these processes, tanning, on variations...

The perception of realism in computer-generated images can be significantly enhanced by subtle visual cues. Among those, one can highlight the presence of dust on synthetic objects, which is often subject to temporal variations in real settings. In this paper, we present a framework for the generation of textures representing the accumulation of th...

A wide range of devices are being routinely used in the noninvasive screening and monitoring of medical conditions through the analysis of skin spectral responses. The correct interpretation of these responses often depends on the availability of high-fidelity characterization datasets for the selected specimens. More specifically, the higher their...

When ultraviolet radiation is absorbed within the cutaneous tissues, it can trigger a number of phenomena that can have detrimental or beneficial consequences to an individual's health. Tanning is among the most visually noticeable of these phenomena. It may result in significant changes in skin pigmentation and thickness. These spectrally-dependen...

Snow is a fundamental component of the climate system. It is also an important part of the planet's hydrological cycle. Accordingly, the investigation of its light scattering properties is essential for remote sensing applications employed in the estimation of changes in the current amount of snowpack. These wide-scale environmental changes are key...

Porosity is a fundamental characteristic of naturally occurring sand-textured soils, commonly referred to as natural sands, found in a wide range of landscapes, from beaches to dune fields. As a primary determinant of the density and permeability of sediments, it represents a pivotal element in geophysical studies involving basin modeling and the o...

The visual fidelity of realistic renderings in Computer Graphics depends fundamentally upon how we model the appearance of objects resulting from the interaction between light and matter reaching the eye. In this paper, we survey the research addressing appearance modelling of living human tissue. Among the many classes of natural materials already...

The presence of abnormal amounts of bilirubin in the blood stream and skin, usually referred to as hyperbilirubinemia, is associated with a wide range of pathologies that can pose considerable risks for human health. The early and effective screening of the severity degrees of this medical condition can play an important role on the selection of th...

The exposure of human skin to ultraviolet radiation (UVR) can trigger a wide array of biological responses, including photocarcinogenesis. Melanin, either in colloidal form or encapsulated into melanosomes, is known to be the main UVR attenuation substance acting within the cutaneous tissues. Although many studies have addressed the protective role...

Methemoglobinemia and sulfhemoglobinemia are potentially life-threatening blood-related disorders characterized by similar symptoms and markedly distinct treatment procedures. In this paper, we investigate the causal relationship between these conditions and the onset of cyanosis, which is typically associated with a purple or bluish skin coloratio...

The reliable detection and monitoring of changes in the water status of crops composed of plants like maize, a highly adaptable C4 species in large demand for both food and biofuel production, are longstanding remote sensing goals. Existing procedures employed to achieve these goals rely predominantly on the spectral signatures of plant leaves in t...

The purple or blue coloration of hands and feet, known as peripheral cyanosis, can represent one of the initial signs of potentially life threatening medical conditions. Consequently, procedures aimed at its early detection and interpretation can help health-care professionals to select the appropriate treatment for these conditions. The effectiven...

Methemoglobinemia and sulfhemoglobinemia are rare, but potentially life threatening, diseases that refer to an abnormal amount of methemoglobin or sulfhemoglobin in the blood, respectively. Unfortunately, blood samples containing abnormal quantities of methemoglobin or sulfhemoglobin have similar spectral characteristics. This makes it difficult to...

Peripheral cyanosis, the purple or blue coloration of hands and feet, can represent the initial signs of life-threatening medical conditions such as heart failure due to coronary occlusion. This makes its effective detection relevant for the timely screening of such conditions. In order to reduce the probability of false negatives during the assess...

Measurement of the optical absorptance of blood can provide insight into its composition and behaviour. Accordingly, optical devices and sensors are commonly used in a clinical setting to measure the absorptance of blood, either directly or indirectly through measurement of skin spectral responses. These measurements enable the evaluation or consta...

By separating the surface and subsurface components of foliar hyperspectral signatures using polarization optics, it is possible to enhance the remote discrimination of different plant species and optimize the assessment of different factors associated with their health status. These initiatives, in turn, can lead to higher crop yield and lower env...

Predictive light transport models based on first-principles simulation approaches have been proposed for complex organic materials. The driving force behind these efforts has been the high-fidelity reproduction of material appearance attributes without one having to rely on the manipulation of ad hoc parameters. These models, however, are usually c...

The interactions of light with the skin surface are controlled by its intrinsic optical properties. In this chapter, we examine these properties from a first-principles point of view, i.e., we focus on the main light-attenuation agents acting within healthy cutaneous tissues. The mechanisms of light attenuation, namely, scattering and absorption, a...

Appearance changes caused by light exposure provide important cues that impart a sense of realism to a computer-generated scene. For instance, a carpet may fade or wood may turn yellow over time as a result of many years of light exposure. In this paper, we analyse the key performance and accuracy trade-offs associated with the physically-based sim...

The water status of cultivated plants can have a significant impact not only on food production, but also on the appropriate usage of increasingly scarce freshwater supplies. Accordingly, the cost-effective detection and monitoring of changes in their water content are longstanding remote sensing goals. Existing procedures employed to achieve these g...

Hyperspectral technologies are being increasingly employed in precision agriculture. By separating the surface and subsurface components of foliar hyperspectral signatures using polarization optics, it is possible to enhance the remote discrimination of different plant species and optimize the assessment of different factors associated with the cro...

The main purpose of this tutorial is to address theoretical and practical issues involved in the development of predictive material appearancemodels for interdisciplinary applications within and outside the visible spectral domain. We examine the specific constraints and pitfalls found in each of the key stages of the model development framework, n...

Anemia is a prevalent medical condition that seriously affects millions of people all over the world. In many regions, not only its initial detection but also its monitoring are hindered by limited access to laboratory facilities. This situation has motivated the development of a wide range of optical devices and procedures to assist physicians in...

The identification and interpretation of skin spectral responses play a central role in a wide range of biomedical engineering applications, from the noninvasive assessment of human health parameters to the location of individuals in distress during search and rescue operations. In this paper, we investigate the sensitivity of these responses to ph...

Several techniques employed in the in vivo estimation of epidermal melanin content rely on the assumption that the effects of different distribution patterns of aggregated melanin (clustered within the melanosomes) on skin spectral responses, particularly across the 600-1350 nm range, can be ignored. Accordingly, for all practical purposes, only th...

In this paper, we investigate techniques for reducing the dimensionality of skin hyperspectral reflectance databases and maintaining a high degree of fidelity during data reconstruction. We compare results obtained using principal components analysis (PCA) with results provided by a piecewise PCA approach that explores the different roles performed...

We propose a multispectral index to assist the detection of human signatures in complex natural environments. Differently from previously proposed indices, it takes into account the spectral responses of human skin not only in the near infrared, but also in the visible region of the light spectrum. As a result, it can contribute to mitigate the cha...

The mineralogy and environmental history of Mars are being extensively studied through remote sensing observations paired with laboratory and in situ experiments. A significant portion of these experiments is being devoted to the identification and mapping of different iron oxides present in the Martian terrains. Among these compounds, goethite has...

Exploration of the hyperspectral domain offers a host of new research and application possibilities involving material appearance modeling. In this article, we address these prospects with respect to human skin, one of the most ubiquitous materials portrayed in synthetic imaging. We present the first hyperspectral model designed for the predictive...

The interactions of light with the skin surface are controlled by its intrinsic optical properties. In this chapter, we examine these properties from a first-principles point of view, i.e., we focus on the main light-attenuation agents acting within healthy cutaneous tissues. The mechanisms of light attenuation, namely, scattering and absorption, a...

The mineralogy and environmental history of Mars are been extensively investigated through remote sensing observations paired with laboratory and in situ experiments. A significant portion of these experiments is being devoted to the identification and quantification of different iron oxides present in the Martian terrains. Although such experiment...

The overall shape of a sand grain can be defined by two morphological properties, namely sphericity and roundness, and it is largely determined by soil-formation and weathering processes. In this paper, we investigate the effects of these properties on the visible and near-infrared reflectance of sand-textured soils characterized by the presence of...

Recently, several papers discussing the application of radiosity in illuminating engineering simulations have been published. The computation of form factors, which specify the fraction of radiation power that leaves one surface and arrives at another, is central to this approach. The errors introduced by form-factor computation directly affect the...

In this paper, we propose a novel approach to discriminate malignant melanomas and benign atypical nevi, since both types of melanocytic skin lesions have very similar characteristics. Recent studies involving the non-invasive diagnosis of melanoma indicate that the concentrations of the two main classes of melanin present in the human skin, eumela...

In this paper, we investigate the effects of sand grain shape on the reflectance of sandy landscapes within the visible domain. Our investigation is supported by computer simulations performed using SPLITS (Spectral Light TransportModel for Sand) and taking into account actual sand characterization data. Our findings indicate that the spectral effe...

The fading of materials due to light exposure over time is a major contributor to the overall aged appearance of man-made objects. Although much attention has been devoted to the modeling of aging and weathering phenomena over the last decade, comparatively little attention has been paid to fading effects. In this article, we present a theoretical...

The different photosynthetic and morphological characteristics of C3 and C4 plants may lead to distinct physiological responses of C3 and C4 crops to stress factors. These responses are strongly correlated with the red edge of these plants, the s-shaped curve in the 680-800nm region of their reflectance spectra. We performed controlled in silico ex...

There are several pathologies whose study and diagnosis is impaired by a relatively small number of documented cases. A practical approach to overcome this obstacle and advance the research in this area consists in employing computer simulations to perform controlled in silico experiments. The results of these experiments, in turn, may be incorpora...

The development of predictive appearance models for organic tissues is a challenging task due to the inherent complexity of these materials. In this report, we closely examine the biophysical processes responsible for the appearance attributes of whole blood, one the most fundamental of these materials. We describe a new appearance model that simul...

Light transport models are employed in applications in such varied areas as realistic image synthesis, noninvasive treatment of diseases, and remote sensing of natural resources. Openly accessible research resources can lead to significant advances involving these applications by fostering the cross-fertilization of different scientific disciplines...

The development of predictive appearance models for organic tissues is a challenging task due to the inherent complexity of these materials. In this paper, we closely examine the biophysical processes responsible for the appearance attributes of whole blood, one the most fundamental of these materials. We describe a new appearance model that simula...

2 Halo Phenomena 5 2.1 General description of halo phenomena.............. 5

Monocotyledonous (C 4) plants, such as maize and sugarcane, have a central role in the economy and ecology of our planet. In many regions, the main food sources are based on C 4 crops. These crops are also major suppliers of raw materials used in the production of biofuel. Due to their increasing global demand, it becomes essential not only to moni...

This chapter provides the physical background for the discussion of the processes of light interaction with human skin. It starts with a brief discussion of the nature of light and a concise review of fundamental optics concepts. This presentation is then followed by an overview of the main light and matter interaction processes and the physical te...

To accurately simulate the mechanisms of light propagation and absorption that determine visual attributes of the skin, it is necessary to carefully account for its biophysical and structural characteristics. This chapter examines these characteristics and how they affect skin optics and ultimately its appearance, which may vary considerably not on...

One would like to use the lowest possible level of abstraction in the design of biophysically based local lighting models so that even small perturbations in the biophysical processes scan be accounted for. In practice, the appropriate abstraction level is usually tied to data availability. First-principles models attempt to work on the lowest leve...

Light transport algorithms form the core of simulation frameworks aimed at the realistic rendering of human skin. The development of such algorithms relies on the application of a scientifically sound methodology that involves data gathering, modeling, and evaluation procedures. This development process is affected by a number of theoretical and pr...

This chapter examines a class of local lighting models whose design was based on the application of the diffusion theory. These models were developed primarily to be incorporated into image-synthesis pipelines. The chapter starts with the review of the model proposed by Jensen et al., henceforth referred to as DT model. This model applies the gener...

The simulation of light interaction with human skin has been an object of extensive research in many fields for decades. To fully assess the efforts made by the computer graphics community toward the predictive modeling of skin appearance, it is essential to revisit seminal works that provide the basis for this line of computer graphics research. F...

One of the main driving forces of computer graphics has been the generation of believable images. In the case of human skin, such images can simply result from biophysically inspired simulations, i.e., they can be produced without resorting to sophisticated biophysically based models. It is remarked that predictability can make the image-generation...

Different image-synthesis frameworks can be used to realistically render the appearance of human skin. They share a similar pipeline structure. The stages of this pipeline include the geometrical representation of skin surfaces, the spectral sampling of light sources, the modeling of (local) light and skin interactions, the computation of environme...

Initially, local lighting models were designed to be applied to many different materials. However, slowly the model design became more specialized, especially with respect to organic materials. Model designers started to look more closely to material appearance attributes in order to obtain believable results. This approach is known as biophysicall...

Skin is one of the most complex organs in the human body and has been an object of extensive study in life and physical sciences. Among the different environmental stimuli that can affect the appearance of human skin, light triggers the most commonly observed responses. The simulation of these responses from a computer graphics point of view, i.e.,...

Preface and Biographic notes for the special issue on Graphics for Serious Games

Sand is one of the most complex materials found in nature. Undeniably the correct modelling of its appearance attributes (such as hue, lightness, and glossiness) is essential to the realistic image synthesis of a wide range of outdoor scenes. Despite this central role, to date, few simulation efforts have been specifically directed to this ubiquito...

Particle systems have been incorporated into a wide variety of applications in both academia and industry. They can be employed to investigate complex natural phenomena, illustrate scientific concepts and generate special effects for entertainment purposes. Recently, we implemented an educational simulation framework based on particle systems that...

Light may traverse a turbid material, such as blood, without encountering any of its pigment containing structures, a phenomenon known as sieve effect. This phenomenon may result in a decrease in the amount of light absorbed by the material. Accordingly, the corresponding sieve factor needs to be accounted for in optical investigations aimed at the...

Light and Skin Interactions immerses you in one of the most fascinating application areas of computer graphics: appearance simulation. The book first illuminates the fundamental biophysical processes that affect skin appearance, and reviews seminal related works aimed at applications in life and health sciences. It then examines four exemplary mode...

This course addresses practical issues involved in the development of biophysically based appearance models. Because these models are used not only in computer graphics, but also in other scientific applications (for example, noninvasive diagnosis of medical conditions and remote sensing of natural resources), the course also aims to foster cross-f...

The authors have recently proposed a model, based on Monte Carlo methods, to simulate light interaction with sand. In this paper, principal component analysis and regression techniques are applied to yield a compact analytical representation of the spectral reflectance signatures produced by the model. This analytical formulation compares well with...

The author has recently proposed a model to simulate light interactions with monocotyledonous (unifacial) leaves in the infrared domain. In this paper, we evaluate the applicability of this model to simulations performed in the visible (photosynthetic) domain, and aimed at the investigation of biophysical responses triggered by nutrient and water s...

An experimental set-up was devised to record the transmission of red and green HeNe lasers through different types of paper. The measured data was compared with data obtained using the Henyey-Greenstein function (often employed in paper optics models to represent the bulk scattering of material samples) and data obtained using an alternative expone...

Recent research efforts in image synthesis have been directed toward the rendering of believable and predictable images of biological materials. This course addresses an important topic in this area, namely the predictive simulation of skin's appearance.The modeling approaches, algorithms and data examined during this course can be also applied to...

The authors have recently proposed a model, based on Monte Carlo methods, to simulate light interaction with sand. In this paper, principal component analysis (PCA) and regression techniques are applied to yield a compact analytical representation of the spectral reflectance signatures produced by the model. This analytical formulation compares wel...

Due to the importance of plants in the Earth's ecosystem, their photobiological responses have become the subject of extensive research in life sciences. Leaf optical models have been developed to assist in the analysis of remotely sensed data to derive information on leaf biochemistry and anatomy from foliar spectral curves (transmittance and refl...

Plasmas are ubiquitous in the Universe. An understanding of plasma phenomena is therefore of importance in almost every area of astrophysics, from stellar atmospheres to star clusters. Plasmas also occur in daily life both in industrial processes and in consumer products. Recent groundbreaking data is making this the golden age of plasma science. A...

The retrieval of plant biophysical and biochemical properties from high spectral resolution data represents an active area of research within the remote sensing field. Scientific studies in this area are usually supported by computational simulations of light attenuation processes within foliar tissues. In heterogeneous organic materials, like plan...

In this paper, we present a new spectral light transport model for sand. The model employs a novel approach to simulate light interaction with particulate materials which yields both the spectral and spatial (bidirectional reflectance distribution function, or BRDF) responses of sand. Furthermore, the parameters specifying the model are based on th...

A longstanding issue in biomedical research concerns the biophysical factors affecting the color diversity of the human irides and its connection with ocular diseases. Although the pigmentation and morphological characteristics of heavily and moderately pigmented irides have been extensively discussed in the literature, similar studies are scarce f...

Recently, light interactions with organic matter have become the object of detailed investigations by image synthesis researchers. Besides allowing these materials to be rendered in a more intuitive manner, these efforts aim to extend the scope of computer graphics applications to areas such as applied optics and biomedical imaging. There are, howe...

Plants are arguably among the most investigated remote sensing targets. Due to their economical and environmental importance, several models to simulate radiation transport and absorption by foliar tissues have been proposed in remote sensing and related fields. The main goal of this research is to present alternative modeling strategies for the in...