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Wenzel Alban Jakob

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Related publications (37)

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Prism-PET II: Second prototype of the TOF-DOI Prism-PET brain scanner with tapered crystals and inverse rendering reconstruction

Wenzel Alban Jakob, Baptiste Alexandre Marie Philippe Claude Nicolet

Accurate PET quantification of tracer uptake in small brain structures is confounded by low sensitivity and the partial volume effect (PVE) caused by limited spatial resolution. In this study, we present the second prototype of the Prism-PET brain scanner ...

IEEE2024

Projective Sampling for Differentiable Rendering of Geometry

Wenzel Alban Jakob, Nicolas Julien Roussel, Ziyi Zhang

Discontinuous visibility changes at object boundaries remain a persistent source of difficulty in the area of differentiable rendering. Left untreated, they bias computed gradients so severely that even basic optimization tasks fail.|Prior path-space metho ...

2023

Recursive Control Variates for Inverse Rendering

Wenzel Alban Jakob, Baptiste Alexandre Marie Philippe Claude Nicolet

We present a method for reducing errors-variance and bias-in physically based differentiable rendering (PBDR). Typical applications of PBDR repeatedly render a scene as part of an optimization loop involving gradient descent. The actual change introduced b ...

2023

Inverse Rendering for PET Scanner Calibration

Wenzel Alban Jakob, Yu Lin

The significant degradation of reconstructed image resolution and the presence of apparent artifacts can result from sub-millimetric misalignment of scanner configuration in highspatial resolution positron emission tomography (PET) systems. Therefore, ensu ...

IEEE2024

Unbiased Inverse Volume Rendering with Differential Trackers

Wenzel Alban Jakob, Merlin Eléazar Nimier-David

Volumetric representations are popular in inverse rendering because they have a simple parameterization, are smoothly varying, and transparently handle topology changes. However, incorporating the full volumetric transport of light is costly and challengin ...

ASSOC COMPUTING MACHINERY2022

Differentiable Signed Distance Function Rendering

Wenzel Alban Jakob, Delio Aleardo Vicini, Sébastien Nicolas Speierer

Physically-based differentiable rendering has recently emerged as an attractive new technique for solving inverse problems that recover complete 3D scene representations from images. The inversion of shape parameters is of particular interest but also pose ...

ASSOC COMPUTING MACHINERY2022

Radiance Surfaces: Optimizing Surface Representations with a 5D Radiance Field Loss

Wenzel Alban Jakob, Tizian Lucien Zeltner, Merlin Eléazar Nimier-David, Nicolas Julien Roussel, Ziyi Zhang

We present a fast and simple technique to convert images into a radiance surface-based scene representation. Building on existing radiance volume reconstruction algorithms, we introduce a subtle yet impactful modification of the loss function requiring cha ...

ACM2025

Mitsuba 2: A Retargetable Forward and Inverse Renderer

Wenzel Alban Jakob, Tizian Lucien Zeltner, Merlin Eléazar Nimier-David, Delio Aleardo Vicini

Modern rendering systems are confronted with a dauntingly large and growing set of requirements: in their pursuit of realism, physically based techniques must increasingly account for intricate properties of light, such as its spectral composition or polar ...

ASSOC COMPUTING MACHINERY2019

Large Steps in Inverse Rendering of Geometry

Wenzel Alban Jakob, Baptiste Alexandre Marie Philippe Claude Nicolet

Inverse reconstruction from images is a central problem in many scientific and engineering disciplines. Recent progress on differentiable rendering has led to methods that can efficiently differentiate the full process of image formation with respect to mi ...

ASSOC COMPUTING MACHINERY2021

Unified Neural Encoding of BTFs

Wenzel Alban Jakob

Realistic rendering using discrete reflectance measurements is challenging, because arbitrary directions on the light and view hemispheres are queried at render time, incurring large memory requirements and the need for interpolation. This explains the des ...

WILEY2020

A Non-Exponential Transmittance Model for Volumetric Scene Representations

Wenzel Alban Jakob, Delio Aleardo Vicini

We introduce a novel transmittance model to improve the volumetric representation of 3D scenes. The model can represent opaque surfaces in the volumetric light transport framework. Volumetric representations are useful for complex scenes, and become increa ...

ASSOC COMPUTING MACHINERY2021

Wide Gamut Spectral Upsampling with Fluorescence

Wenzel Alban Jakob

Physically based spectral rendering has become increasingly important in recent years. However, asset textures in such systems are usually still drawn or acquired as RGB tristimulus values. While a number of RGB to spectrum upsampling techniques are availa ...

2019

MCMC: Bridging Rendering, Optimization and Generative AI

Wenzel Alban Jakob

Generative artificial intelligence (AI) has made unprecedented advances in vision language models over the past two years. These advances are largely due to diffusion-based generative models, which are very stable and simple to train. These diffusion model ...

Association for Computing Machinery, Inc2024

Inverse Rendering for Tomographic Volumetric Additive Manufacturing

Christophe Moser, Wenzel Alban Jakob, Jorge Andres Madrid Wolff, Baptiste Alexandre Marie Philippe Claude Nicolet, Felix Wechsler

Tomographic Volumetric Additive Manufacturing (TVAM) is an emerging 3D printing technology that can create complex objects in under a minute. The key idea is to project intense light patterns onto a rotating vial of photo-sensitive resin, causing polymeriz ...

Association for Computing Machinery (ACM)2024

Solving Inverse PDE Problems using Grid-Free Monte Carlo Estimators

Ekrem Fatih Yilmazer, Wenzel Alban Jakob

Partial differential equations can model diverse physical phenomena including heat diffusion, incompressible flows, and electrostatic potentials. Given a description of an object's boundary and interior, traditional methods solve such PDEs by densely meshi ...

Association for Computing Machinery (ACM)2024

Neural BTF Compression and Interpolation

Wenzel Alban Jakob

The Bidirectional Texture Function (BTF) is a data-driven solution to render materials with complex appearance. A typical capture contains tens of thousands of images of a material sample under varying viewing and lighting conditions. While capable of fait ...

WILEY2019

Inverse Rendering for PET Image Reconstruction

Wenzel Alban Jakob, Baptiste Alexandre Marie Philippe Claude Nicolet

Differentiable rendering (DR) is an emerging field that facilitates the calculation and propagation of gradients of 3D objects through images. In contrast to deep neural networks (DNNs), which generally lack the understanding of 3D objects that form the im ...

IEEE2024

Specular Manifold Sampling for Rendering High-Frequency Caustics and Glints

Wenzel Alban Jakob, Tizian Lucien Zeltner

Scattering from specular surfaces produces complex optical effects that are frequently encountered in realistic scenes: intricate caustics due to focused reflection, multiple refraction, and high-frequency glints from specular microstructure. Yet, despite ...

ASSOC COMPUTING MACHINERY2020

Reparameterizing Discontinuous Integrands for Differentiable Rendering

Wenzel Alban Jakob, Guillaume Rémi Bruno Loubet

Differentiable rendering has recently opened the door to a number of challenging inverse problems involving photorealistic images, such as computational material design and scattering-aware reconstruction of geometry and materials from photographs. Differe ...

ASSOC COMPUTING MACHINERY2019

Quantifying the Error of Light Transport Algorithms

Wenzel Alban Jakob

This paper proposes a new methodology for measuring the error of unbiased physically based rendering algorithms. The current state of the art includes mean squared error (MSE) based metrics and visual comparisons of equal-time renderings of competing algor ...

2019