Alex Keller ![](/sites/default/files/person/2020small.jpg) Alexander Keller is a Senior Director of Research at NVIDIA. Before, he had been the Chief Scientist of mental images, where he had been responsible for research and the conception of future products and strategies including the design of the NVIDIA Iray light transport simulation and rendering system. Prior to industry, he worked as a full professor for computer graphics and scientific computing at Ulm University, where he co-founded the UZWR (Ulmer Zentrum für wissenschaftliches Rechnen) and received an award for excellence in teaching. Alexander Keller has more than 3 decades of experience in ray tracing, pioneered quasi-Monte Carlo methods for light transport simulation, and connected the domains of machine learning and rendering. His research interests are at the intersection of graphics, communications, and machine learning. Research Area(s) [Algorithms and Numerical Methods](/research-area/algorithms) [Artificial Intelligence and Machine Learning ](/research-area/machine-learning-artificial-intelligence) [Computer Graphics](/research-area/computer-graphics) [Real-Time Rendering](/research-area/real-time-rendering) [Telecommunications](/research-area/telecommunications) Google Scholar [https://scholar.google.de/citations?user=kqyUhBIAAAAJ&hl=en&oi=ao](https://scholar.google.de/citations?user=kqyUhBIAAAAJ&hl=en&oi=ao) ### Publications ### 2025 [SALAD: Self-Adaptive Link Adaptation](/publication/2025-10_salad-self-adaptive-link-adaptation) Reinhard Wiesmayr, [Lorenzo Maggi](/person/lorenzo-maggi), [Sebastian Cammerer](/person/sebastian-cammerer), [Jakob Hoydis](/person/jakob-hoydis), [Fayçal Aït Aoudia ](/person/faycal-ait-aoudia), [Alex Keller](/person/alex-keller) [arXiv](https://arxiv.org/pdf/2510.05784) [GEN3C: 3D-Informed World-Consistent Video Generation with Precise Camera Control](/publication/2025-08_gen3c-3d-informed-world-consistent-video-generation-precise-camera-control) Xuanchi Ren, Tianchang Shen, Jiahui Huang, Huan Ling, Yifan Lu, [Merlin Nimier-David](/person/merlin-nimier-david), [Thomas Müller](/person/thomas-muller), [Alex Keller](/person/alex-keller), [Sanja Fidler](/person/sanja-fidler), Jun Gao [CVPR 2025](https://ieeexplore.ieee.org/document/11092782) [FourCastNet 3: A geometric approach to probabilistic machine-learning weather forecasting at scale](/publication/2025-07_fourcastnet-3-geometric-approach-probabilistic-machine-learning-weather) [Boris Bonev](/person/boris-bonev), Thorsten Kurth, Ankur Mahesh, Mauro Bisson, [Jean Kossaifi](/person/jean-kossaifi), Karthik Kashinath, Anima Anandkumar, William D. Collins, [Mike Pritchard](/person/mike-pritchard), [Alex Keller](/person/alex-keller) [Sionna Research Kit: A GPU-Accelerated Research Platform for AI-RAN](/publication/2025-05_sionna-research-kit-gpu-accelerated-research-platform-ai-ran) [Sebastian Cammerer](/person/sebastian-cammerer), [Guillermo Marcus](/person/guillermo-marcus), [Tobias Zirr](/person/tobias-zirr), [Fayçal Aït Aoudia ](/person/faycal-ait-aoudia), [Lorenzo Maggi](/person/lorenzo-maggi), [Jakob Hoydis](/person/jakob-hoydis), [Alex Keller](/person/alex-keller) [2025 IEEE International Conference on Machine Learning for Communication and Ne…](https://arxiv.org/pdf/2505.15848) [Design of a Standard-Compliant Real-Time Neural Receiver for 5G NR](/publication/2025-05_design-standard-compliant-real-time-neural-receiver-5g-nr) Reinhard Wiesmayr, [Sebastian Cammerer](/person/sebastian-cammerer), [Fayçal Aït Aoudia ](/person/faycal-ait-aoudia), [Jakob Hoydis](/person/jakob-hoydis), Jakub Zakrzewski, [Alex Keller](/person/alex-keller) [IEEE International Conference on Machine Learning for Communication and Network…](https://ieeexplore.ieee.org/abstract/document/11140048) [Sionna RT: Technical Report](/publication/2025-04_sionna-rt-technical-report) [Fayçal Aït Aoudia ](/person/faycal-ait-aoudia), [Jakob Hoydis](/person/jakob-hoydis), [Merlin Nimier-David](/person/merlin-nimier-david), [Sebastian Cammerer](/person/sebastian-cammerer), [Alex Keller](/person/alex-keller) ### 2024 [Conformer without Convolutions](/publication/2024-09_conformer-without-convolutions) [Matthijs Van keirsbilck](/person/matthijs-van-keirsbilck), [Alex Keller](/person/alex-keller) [Interspeech 2024](https://www.isca-archive.org/interspeech_2024/vankeirsbilck24_interspeech.pdf) ### 2023 [Compact Neural Graphics Primitives with Learned Hash Probing](/publication/2023-12_compact-neural-graphics-primitives-learned-hash-probing) Towaki Takikawa, [Thomas Müller](/person/thomas-muller), [Merlin Nimier-David](/person/merlin-nimier-david), Alex Evans, [Sanja Fidler](/person/sanja-fidler), Alec Jacobson, [Alex Keller](/person/alex-keller) [SIGGRAPH Asia 2023](https://dl.acm.org/doi/10.1145/3610548.3618167) [Adaptive Shells for Efficient Neural Radiance Field Rendering](/publication/2023-12_adaptive-shells-efficient-neural-radiance-field-rendering) Zian Wang, Tianchang Shen, [Merlin Nimier-David](/person/merlin-nimier-david), Nicholas Sharp, Jun Gao, [Alex Keller](/person/alex-keller), [Sanja Fidler](/person/sanja-fidler), [Thomas Müller](/person/thomas-muller), Zan Gojcic [SIGGRAPH Asia 2023](https://dl.acm.org/doi/10.1145/3618390) SIGGRAPH Asia 2023 Best Paper Award [Sionna RT: Differentiable Ray Tracing for Radio Propagation Modeling](/publication/2023-12_sionna-rt-differentiable-ray-tracing-radio-propagation-modeling) [Jakob Hoydis](/person/jakob-hoydis), [Fayçal Aït Aoudia ](/person/faycal-ait-aoudia), [Sebastian Cammerer](/person/sebastian-cammerer), [Merlin Nimier-David](/person/merlin-nimier-david), [Nikolaus Binder](/person/nikolaus-binder), [Guillermo Marcus](/person/guillermo-marcus), [Alex Keller](/person/alex-keller) [IEEE Globecom Workshops (GC Wkshps) 2023](https://globecom2023.ieee-globecom.org/) [A Neural Receiver for 5G NR Multi-user MIMO](/index.php/publication/2023-12_neural-receiver-5g-nr-multi-user-mimo) [Sebastian Cammerer](/index.php/person/sebastian-cammerer), [Fayçal Aït Aoudia ](/index.php/person/faycal-ait-aoudia), [Jakob Hoydis](/index.php/person/jakob-hoydis), Andreas Oeldemann, Andreas Roessler, Timo Mayer, [Alex Keller](/index.php/person/alex-keller) [IEEE Globecom Workshops (GC Wkshps) 2023](https://globecom2023.ieee-globecom.org/) [Recursive Control Variates for Inverse Rendering](/publication/2023-05_recursive-control-variates-inverse-rendering) Baptiste Nicolet, [Fabrice Rousselle](/person/fabrice-rousselle), [Jan Novák](/person/jan-novak), [Alexander Keller](/person/alex-keller), Wenzel Jakob, [Thomas Müller](/person/thomas-muller) [SIGGRAPH 2023](https://s2023.siggraph.org) ### 2022 [Deep Learning-Based Synchronization for Uplink NB-IoT](/index.php/publication/2022-12_deep-learning-based-synchronization-uplink-nb-iot) [Fayçal Aït Aoudia ](/index.php/person/faycal-ait-aoudia), [Jakob Hoydis](/index.php/person/jakob-hoydis), [Sebastian Cammerer](/index.php/person/sebastian-cammerer), [Matthijs Van keirsbilck](/index.php/person/matthijs-van-keirsbilck), [Alex Keller](/index.php/person/alex-keller) [IEEE Global Communications Conference 2022](https://ieeexplore.ieee.org/abstract/document/10001353) [Graph Neural Networks for Channel Decoding](/publication/2022-12_graph-neural-networks-channel-decoding) [Sebastian Cammerer](/person/sebastian-cammerer), [Jakob Hoydis](/person/jakob-hoydis), [Fayçal Aït Aoudia ](/person/faycal-ait-aoudia), [Alex Keller](/person/alex-keller) [IEEE Globecom Workshops (GC Wkshps) 2022](https://ieeexplore.ieee.org/abstract/document/10008601/) [Towards Adaptive Digital Self-Interference Cancellation in Full-Duplex Wireless Transceivers: APSM vs. Neural Networks](/publication/2022-10_towards-adaptive-digital-self-interference-cancellation-full-duplex-wireless) M. Hossein Attar, Kaixin Chang, Ramez Askar, Slawomir Stanczak, [Sebastian Cammerer](/person/sebastian-cammerer), [Guillermo Marcus](/person/guillermo-marcus), [Alex Keller](/person/alex-keller) [Asilomar Conference on Signals, Systems, and Computers 2022](https://ieeexplore.ieee.org/abstract/document/10052049) [GPU-Accelerated Machine Learning in Non-Orthogonal Multiple Access](/publication/2022-08_gpu-accelerated-machine-learning-non-orthogonal-multiple-access) Daniel Schäufele, [Guillermo Marcus](/person/guillermo-marcus), [Nikolaus Binder](/person/nikolaus-binder), Matthias Mehlhose, [Alex Keller](/person/alex-keller), Slawomir Stańczak [2022 30th European Signal Processing Conference (EUSIPCO)](https://ieeexplore.ieee.org/document/9909865) [Instant Neural Graphics Primitives with a Multiresolution Hash Encoding](/publication/2022-07_instant-neural-graphics-primitives-multiresolution-hash-encoding) [Thomas Müller](/person/thomas-muller), Alex Evans, Christoph Schied, [Alex Keller](/person/alex-keller) [ACM Transactions on Graphics (SIGGRAPH 2022)](https://s2022.siggraph.org) Best Technical Paper, SIGGRAPH 2022, THE BEST INVENTIONS OF 2022, TIME [Unbiased Inverse Volume Rendering With Differential Trackers](/publication/2022-07_unbiased-inverse-volume-rendering-differential-trackers) Merlin Nimier-David, [Thomas Müller](/person/thomas-muller), [Alex Keller](/person/alex-keller), Wenzel Jakob [ACM Transactions on Graphics (SIGGRAPH 2022)](https://s2022.siggraph.org) [GPU-Accelerated Partially Linear Multiuser Detection for 5G and Beyond URLLC Systems](/publication/2022-06_gpu-accelerated-partially-linear-multiuser-detection-5g-and-beyond-urllc) Matthias Mehlhose, [Guillermo Marcus](/person/guillermo-marcus), Daniel Schäufele, Daniyal Amir Awan, [Nikolaus Binder](/person/nikolaus-binder), Martin Kasparick, Renato L. G. Cavalcante, Sławomir Stanćzak , [Alex Keller](/person/alex-keller) [IEEE Access](https://ieeexplore.ieee.org/abstract/document/9810242) [MatBuilder: Mastering Sampling Uniformity Over Projections](/publication/2022-05_matbuilder-mastering-sampling-uniformity-over-projections) Loïs Paulin, Nicolas Bonneel, David Coeurjolly, Jean-Claude Iehl, [Alex Keller](/person/alex-keller), Victor Ostromoukhov [ACM Transactions on Graphics (SIGGRAPH 2022)](https://s2022.siggraph.org) [MatBuilder: Mastering Sampling Uniformity Over Projections](/publication/2022-05_matbuilder-mastering-sampling-uniformity-over-projections) Loïs Paulin, Nicolas Bonneel, David Coeurjolly, Jean-Claude Iehl, [Alex Keller](/person/alex-keller), Victor Ostromoukhov [ACM Transactions on Graphics (SIGGRAPH 2022)](https://s2022.siggraph.org) [Artificial Neural Networks generated by Low Discrepancy Sequences](/publication/2022-05_artificial-neural-networks-generated-low-discrepancy-sequences) [Matthijs Van keirsbilck](/person/matthijs-van-keirsbilck), [Alex Keller](/person/alex-keller) [arxiv link](https://arxiv.org/pdf/2103.03543.pdf) [Sionna: An Open-Source Library for Next-Generation Physical Layer Research](/publication/2022-03_sionna-open-source-library-next-generation-physical-layer-research) [Jakob Hoydis](/person/jakob-hoydis), [Sebastian Cammerer](/person/sebastian-cammerer), [Fayçal Aït Aoudia ](/person/faycal-ait-aoudia), Avinash Vem, [Nikolaus Binder](/person/nikolaus-binder), [Guillermo Marcus](/person/guillermo-marcus), [Alex Keller](/person/alex-keller) [arXiv](https://arxiv.org/pdf/2203.11854.pdf) [RTMV: A Ray-Traced Multi-View Synthetic Dataset for Novel View Synthesis ](/publication/2022-01_rtmv-ray-traced-multi-view-synthetic-dataset-novel-view-synthesis) [Jonathan Tremblay](/person/jonathan-tremblay), Moustafa Meshry, [Stan Birchfield](/person/stan-birchfield), Alex Evans, [Jan Kautz](/person/jan-kautz), [Alex Keller](/person/alex-keller), Sameh Khamis, [Charles Loop](/person/charles-loop), Nate Morrical, [Thomas Müller](/person/thomas-muller), [Koki Nagano](/person/koki-nagano), Towaki Takikawa, [Stan Birchfield](/person/stan-birchfield) [ECCV 2022 Workshop on Learning to Generate 3D Shapes and Scenes](https://learn3dg.github.io/) ### 2021 [Dynamic Diffuse Global Illumination Resampling](/publication/2021-12_dynamic-diffuse-global-illumination-resampling) Zander Majercik, [Thomas Müller](/person/thomas-muller), [Alex Keller](/person/alex-keller), Derek Nowrouzezahrai, Morgan McGuire [Computer Graphics Forum](https://onlinelibrary.wiley.com/doi/10.1111/cgf.14427) [Compressing 1D Time-Channel Separable Convolutions using Sparse Random Ternary Matrices](/publication/2021-08_compressing-1d-time-channel-separable-convolutions-using-sparse-random-ternary) Goncalo Mordido, [Matthijs Van keirsbilck](/person/matthijs-van-keirsbilck), [Alex Keller](/person/alex-keller) [Interspeech 2021](https://www.isca-speech.org/archive/pdfs/interspeech_2021/mordido21_interspeech.pdf) [Real-time Neural Radiance Caching for Path Tracing](/publication/2021-06_real-time-neural-radiance-caching-path-tracing) [Thomas Müller](/person/thomas-muller), [Fabrice Rousselle](/person/fabrice-rousselle), [Jan Novák](/person/jan-novak), [Alex Keller](/person/alex-keller) ACM Transactions on Graphics ### 2020 [Neural Control Variates](/publication/2020-11_neural-control-variates) [Thomas Müller](/person/thomas-muller), [Fabrice Rousselle](/person/fabrice-rousselle), [Alex Keller](/person/alex-keller), [Jan Novák](/person/jan-novak) [ACM Transactions on Graphics (SIGGRAPH Asia)](https://dl.acm.org/doi/abs/10.1145/3414685.3417804) [Monte Carlo Gradient Quantization](/publication/2020-06_monte-carlo-gradient-quantization) Goncalo Mordido, [Matthijs Van keirsbilck](/person/matthijs-van-keirsbilck), [Alex Keller](/person/alex-keller) [CVPR2020 Workshop](https://openaccess.thecvf.com/content_CVPRW_2020/papers/w40/Mordido_Monte_Carlo_Gradient_Quantization_CVPRW_2020_paper.pdf) ### 2019 [Instant Quantization of neural networks using Monte Carlo Methods](/publication/2019-12_instant-quantization-neural-networks-using-monte-carlo-methods) Gonçalo Mordido, [Matthijs Van keirsbilck](/person/matthijs-van-keirsbilck), [Alex Keller](/person/alex-keller) [NeurIPS 2019 EMC2 workshop (IEEExplore)](https://ieeexplore.ieee.org/document/9463561) [Rethinking full connectivity in recurrent neural networks](/publication/2019-03_rethinking-full-connectivity-recurrent-neural-networks) [Matthijs Van keirsbilck](/person/matthijs-van-keirsbilck), [Alex Keller](/person/alex-keller), Xiaodong Yang [arxiv paper](https://arxiv.org/pdf/1905.12340.pdf) [Massively Parallel Path Space Filtering](/publication/2019-02_massively-parallel-path-space-filtering) [Nikolaus Binder](/person/nikolaus-binder), Sascha Fricke, [Alex Keller](/person/alex-keller) [arXiv](https://arxiv.org/abs/1902.05942?context=cs) [Massively Parallel Construction of Radix Tree Forests for the Efficient Sampling of Discrete Probability Distributions](/publication/2019-01_massively-parallel-construction-radix-tree-forests-efficient-sampling-discrete) [Nikolaus Binder](/person/nikolaus-binder), [Alex Keller](/person/alex-keller) [arXiv](https://arxiv.org/abs/1901.05423) ### 2018 [Fast, High Precision Ray/Fiber Intersection using Tight, Disjoint Bounding Volumes](/publication/2018-11_fast-high-precision-rayfiber-intersection-using-tight-disjoint-bounding-volumes) [Nikolaus Binder](/person/nikolaus-binder), [Alex Keller](/person/alex-keller) [arXiv](https://arxiv.org/abs/1811.03374) [Massively Parallel Stackless Ray Tracing of Catmull-Clark Subdivision Surfaces](/publication/2018-11_massively-parallel-stackless-ray-tracing-catmull-clark-subdivision-surfaces) [Nikolaus Binder](/person/nikolaus-binder), [Alex Keller](/person/alex-keller) [arXiv](https://arxiv.org/abs/1811.03510) [Machine Learning and Rendering](/publication/2018-08_machine-learning-and-rendering) [Alex Keller](/person/alex-keller), Jaroslav Křivánek, Jan Novák, Anton Kaplanyan, Marco Salvi [ACM SIGGRAPH 2018 Courses](https://dl.acm.org/citation.cfm?doid=3214834.3214841) ### 2017 [Integral Equations and Machine Learning](/publication/2017-12_integral-equations-and-machine-learning) [Alex Keller](/person/alex-keller), Ken Dahm [Mathematics and Computers in Simulation, Volume 161, July 2019, Pages 2-12](https://www.sciencedirect.com/science/article/abs/pii/S0378475419300308) [The Iray Light Transport Simulation and Rendering System](/publication/2017-05_iray-light-transport-simulation-and-rendering-system) [Alex Keller](/person/alex-keller), Carsten Wächter, Matthias Raab, Daniel Seibert, Dietger van Antwerpen, Johann Korndörfer, Lutz Kettner [arXiv](https://arxiv.org/abs/1705.01263) [Learning Light Transport the Reinforced Way](/publication/2017-01_learning-light-transport-reinforced-way) Ken Dahm, [Alex Keller](/person/alex-keller) [arXiv](https://arxiv.org/abs/1701.07403) ### 2016 [GI next: global illumination for production rendering on GPUs](/publication/2016-07_gi-next-global-illumination-production-rendering-gpus) Enzo Catalano, Rajko Yasui-Schöffel , Ken Dahm, [Nikolaus Binder](/person/nikolaus-binder), [Alex Keller](/person/alex-keller) [ACM SIGGRAPH 2016 Talks](http://doi.acm.org/10.1145/2897839.2927452) [Efficient stackless hierarchy traversal on GPUs with backtracking in constant time](/publication/2016-06_efficient-stackless-hierarchy-traversal-gpus-backtracking-constant-time) [Nikolaus Binder](/person/nikolaus-binder), [Alex Keller](/person/alex-keller) [Proceedings of High Performance Graphics](http://dl.acm.org/citation.cfm?id=2977336.2977343) ### 2015 [Stackless ray tracing of patches from feature-adaptive subdivision on GPUs](/publication/2015-07_stackless-ray-tracing-patches-feature-adaptive-subdivision-gpus) [Nikolaus Binder](/person/nikolaus-binder), [Alex Keller](/person/alex-keller) [ACM SIGGRAPH 2015 Talks](http://doi.acm.org/10.1145/2775280.2792551) ### 2014 [Path space filtering](/publication/2014-10_path-space-filtering) [Alex Keller](/person/alex-keller), Ken Dahm, [Nikolaus Binder](/person/nikolaus-binder) [ACM SIGGRAPH 2014 Talks](http://doi.acm.org/10.1145/2614106.2614149) [Path space similarity determined by Fourier histogram descriptors](/publication/2014-07_path-space-similarity-determined-fourier-histogram-descriptors) Pascal Gautron, Marc Droske, Carsten Wächter, Lutz Kettner, [Alex Keller](/person/alex-keller), [Nikolaus Binder](/person/nikolaus-binder), Ken Dahm [ACM SIGGRAPH 2014 Talks](http://doi.acm.org/10.1145/2614106.2614117) [A Decomposition for In-place Array Transposition](/publication/2014-02_decomposition-place-array-transposition) Bryan Catanzaro, [Alex Keller](/person/alex-keller), [Michael Garland](/person/michael-garland) [PPoPP 2014](http://dx.doi.org/10.1145/2555243.2555253) ### 2013 [Deterministic Consistent Density Estimation for Light Transport Simulation](/publication/2013-11_deterministic-consistent-density-estimation-light-transport-simulation) [Alex Keller](/person/alex-keller), [Nikolaus Binder](/person/nikolaus-binder) [Monte Carlo and Quasi-Monte Carlo Methods 2012](http://dx.doi.org/10.1007/978-3-642-41095-6_23)