MAM2024 - MANER Conference London 2024

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https://diglib.eg.org/handle/10.2312/3607038

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    The Challenges of Relighting from Multi-View Observations
    (The Eurographics Association, 2024) Siersleben, Daniel; Ortiz-Cayon, Rodrigo; Istenic, Klemen; Tomoto, Yusuke; Schaub-Meyer, Simone; Hardeberg, Jon Yngve; Rushmeier, Holly
    High-quality geometry reconstruction from multi-view images with subsequent appearance decomposition into the physical shading components could enable a seamless integration of neural reconstructions into the modern rendering workflow. While 3D reconstruction techniques have steadily improved, the task of inverse rendering by decomposing an appearance into lighting effects and material properties remains fundamentally ill-posed and highly ambiguous. We show that current state-of-the-art inverse rendering approaches fail to accurately recover material properties, significantly impacting relighting quality. Furthermore, we demonstrate that existing evaluation methods, which rely on image-based metrics, do not adequately capture the reconstruction quality in novel lighting conditions. Our findings illustrate the dependence of current systems on simplified setups with predefined illumination, which are necessary to reliably disentangle light and material contributions and to ultimately achieve convincing relighting.
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    Reflectometer Material Capture
    (The Eurographics Association, 2024) Chan, Danny; Iwanicki, Michal; Hardeberg, Jon Yngve; Rushmeier, Holly
    Physically-based shaders benefit from physically measured material parameters. The Reflectometer is a simple-to-build, portable device that allows measurement of diffuse albedo, smoothness, and specular F0 in the field.
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    Psychophysical Insights into Anisotropic Highlights of 3D Printed Objects
    (The Eurographics Association, 2024) Filip, Jirí; Vítek, Martin; Hardeberg, Jon Yngve; Rushmeier, Holly
    3D printing has been extensively used for over two decades by various practitioners and professionals in the industry. This technique, which involves adding material from melted filament layer by layer based on CAD model geometry, imparts a unique appearance to the printed objects. The layering structure generates specific directional reflectance patterns on printed surfaces, leading to anisotropic highlights. Due to slight inaccuracies in the printing setup, the appearance of individual layers is not seamless and exhibits sparkle-like effects along the highlight. In this paper, we conducted a psychophysical experiment to analyze human perception of the printed objects, focusing on the intensity and width of the anisotropic highlights.We discovered that the contrast near the highlights and the variability of pixel intensities along the highlights are highly correlated with human ratings. Lastly, we present a straightforward method utilizing these computational features to enhance the visualization of 3D printed objects.
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    A Study of Observer Metamerism for Reflectance-induced Stimuli
    (The Eurographics Association, 2024) Fascione, Luca; Hanika, Johannes; Hardeberg, Jon Yngve; Rushmeier, Holly
    Cameras make images collecting per-pixel measurements of light reflected by the objects in the world. Commonly, these measurements undergo a transformation so that they become values in a standardized color space, such as the sRGB space. This makes it possible to send the values to a display device and produce in a human a visual sensation as close as possible to what would have been caused by the original scene. In this work we aim to explore the difficulties and opportunities that arise in devising such non-bijective transformations, visualizing differences between device vision and human vision. In particular we are interested in the practical impact of observer metamerism: different camera devices and human observers can distinguish a different set of spectral stimuli presented to them. When characterizing a camera, this is usually ignored, missing potential to increase chromatic acuity where the camera can see more than the human observer. A question that arises is whether the metameric stimuli involved here do actually appear in practice in relevant cases. We run numeric experiments to investigate these questions.
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    Neural Texture Block Compression
    (The Eurographics Association, 2024) Fujieda, Shin; Harada, Takahiro; Hardeberg, Jon Yngve; Rushmeier, Holly
    Block compression is a widely used technique to compress textures in real-time graphics applications, offering a reduction in storage size. However, their storage efficiency is constrained by the fixed compression ratio, which substantially increases storage size when hundreds of high-quality textures are required. In this paper, we propose a novel block texture compression method with neural networks, Neural Texture Block Compression (NTBC). NTBC learns the mapping from uncompressed textures to block-compressed textures, which allows for significantly reduced storage costs without any change in the shaders. Our experiments show that NTBC can achieve reasonable-quality results with up to about 45% less storage footprint, preserving real-time performance with a modest computational overhead at the texture loading phase in the graphics pipeline.
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    Importance of Multi-modal Reflection Data for Predictive Rendering
    (The Eurographics Association, 2024) Clausen, Olaf; Chen, Yang; Fuhrmann, Arnulph; Marroquim, Ricardo; Hardeberg, Jon Yngve; Rushmeier, Holly
    Accurate modeling of material appearance is crucial for achieving predictive rendering. To improve reflection models, databases with measured reflection behaviors of various material and surface types are of great importance. However, current databases provide limited information, focusing either on the spectral or spatial domain and often lack microgeometry details. To address this limitation, a multi-modal database that includes reflection behavior in both spectral and spatial domains, along with comprehensive microgeometry information, is essential. Additionally, scatter information simulated with microgeometry enhances the understanding of light-matter interactions. This paper discusses the importance of multi-modal reflection data in developing more realistic and computationally efficient reflection models for predictive rendering.
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    Joint MAM - MANER Conference - Material Appearance Network for Education and Research: Frontmatter
    (The Eurographics Association, 2024) Hardeberg, Jon Yngve; Rushmeier, Holly; Hardeberg, Jon Yngve; Rushmeier, Holly
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    Can we Grasp the Color of Translucent Objects?
    (The Eurographics Association, 2024) Gigilashvili, Davit; Chowdhury, Dipayan; Hardeberg, Jon Yngve; Hardeberg, Jon Yngve; Rushmeier, Holly
    While colorimetry is traditionally measuring point colors, there is an increasing need to quantify colors of 3D objects in real-world scenes. 3D objects, especially translucent ones, exhibit high spatio-temporal variation in color. This raises multiple questions on how to measure color of 3D translucent objects, how to describe their color appearance, and how to quantify color differences among them. Or are these ill-posed problems in the first place? We discuss the first steps on this topic and suggest the future directions for color and appearance research.
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    Real Surface Measurement and Virtual Gonioradiometer for Road Appearance Prediction
    (The Eurographics Association, 2024) Xu, Kewei; Ribardière, Mickaël; Bringier, Benjamin; Meneveaux, Daniel; Hardeberg, Jon Yngve; Rushmeier, Holly
    Measuring road appearance in situ requires either very specific hardware difficult to implement, or extracting core samples from used roads. This is why reflectance estimation from virtual samples constructed from non-invasive acquisitions are useful in a wide range of applications. This article proposes an analysis of several combinations for merging geometric and individual reflectance data, in order to estimate the resulting uncertainty, with various distributions.