Portrait of Xiaohan Fei

About Me

I’m a Principal Applied Scientist working on multi-modal foundation models (video generation models in particular) at Amazon Artificial General Intelligence (AGI) org. In the past, I was with AWS AI Labs, and Meta Reality Labs where I worked on several initiatives on 3-D computer vision.

I received my Ph.D. in Computer Science from UCLA in 2019, where I worked with Prof. Stefano Soatto at the UCLA Vision Lab. My dissertation, Inertial-aided Visual Perception of Geometry and Semantics, explored how inertial measurements can improve visual understanding of geometry and semantic structure.

My research spans computer vision, robotics, and machine learning. I am particularly interested in building models and systems that solve real-world problems by combining information across sensors and modalities.

Our paper Geo-Supervised Visual Depth Prediction, which uses inertial measurements and gravity-induced shape priors to improve monocular depth prediction, received the Best Paper Award in Robot Vision at ICRA 2019, selected from 2,900 submissions.

I received my B.Eng. in Information and Communication Engineering from Zhejiang University in 2014. I was also a member of the Advanced Honor Class of Engineering Education at Chu Kochen Honors College, where I developed an enduring interest in mathematical modeling and interdisciplinary engineering.

My current CV is available here.

Awards & Distinctions

Demo

Amazon Nova Video and Image Generation Models

Amazon Nova Reel video generation
Amazon Nova Canvas image generation

Multi-Sensor Localization and Mapping

Visual-Inertial Object Detection and Mapping
XIVO visual-inertial odometry demo at UCLA
XIVO, our open-source visual-inertial odometry system

Additional Demo

What’s New

Software

Theses

Publications

* Equal contribution.

InterPrior humanoids demonstrating snapshot, trajectory, contact, recovery, and steering goals

InterPrior: Scaling Generative Control for Physics-Based Human-Object Interactions

Sirui Xu, Samuel Schulter, Morteza Ziyadi, Xialin He, Xiaohan Fei, Yu-Xiong Wang, and Liangyan Gui. CVPR, 2026.

InterPrior combines large-scale imitation pretraining with reinforcement-learning post-training to produce a versatile physics-based controller that follows sparse goals, recovers from failures, and generalizes human-object interactions to unseen settings.

Input and output modalities supported by the four Amazon Nova 2 models

Amazon Nova 2: Multimodal Reasoning and Generation Models

Amazon Artificial General Intelligence. Technical report, 2025.

Nova 2 introduces four foundation models spanning configurable reasoning, native multimodal understanding and generation, and real-time speech-to-speech interaction, with context windows of up to one million tokens.

Input and output modalities supported by the Amazon Nova model family

The Amazon Nova Family of Models: Technical Report and Model Card

Amazon Artificial General Intelligence. Technical report, 2024.

The original Nova family pairs efficient text and multimodal understanding models with Canvas image generation and Reel video generation, emphasizing price-performance, customization, and responsible development.

Diverse compositional 3D assets generated by Grounded-Dreamer

Grounded Compositional and Diverse Text-to-3D with Pretrained Multi-View Diffusion Model

Xiaolong Li, Jiawei Mo, Ying Wang, Chethan Parameshwara, Xiaohan Fei, Ashwin Swaminathan, CJ Taylor, Zhuowen Tu, Paolo Favaro, and Stefano Soatto. arXiv preprint, 2024.

Grounded-Dreamer uses text-aligned four-view images as an intermediate representation, then combines sparse-view reconstruction with score distillation to generate faithful, diverse 3D assets from complex compositional prompts.

Pipeline for updating a pretrained NeRF from sparse views of a reconfigured scene

Fast Sparse-View Guided NeRF Update for Object Reconfigurations

Ziqi Lu, Jianbo Ye, Xiaohan Fei, Xiaolong Li, Jiawei Mo, Ashwin Swaminathan, and Stefano Soatto. arXiv preprint, 2024.

This method detects physical scene changes from as few as four new images and uses a helper NeRF to update local geometry and appearance in one to two minutes, avoiding full scene recapture and retraining.

Multiple inconsistent views illustrating the Janus failure mode in text-to-3D generation

A Quantitative Evaluation of Score Distillation Sampling Based Text-to-3D

Xiaohan Fei, Chethan Parameshwara, Jiawei Mo, Xiaolong Li, Ashwin Swaminathan, CJ Taylor, Paolo Favaro, and Stefano Soatto. arXiv preprint, 2024.

The work introduces human-validated metrics for the Janus problem, prompt alignment, and 3D realism, then uses the analysis to design an efficient Gaussian-splatting baseline that reduces common score-distillation artifacts.

Comparison of reference images, NeRF renderings, image restoration, and NeRF Diffusion results

Towards Visual Foundational Models of Physical Scenes

Chethan Parameshwara*, Alessandro Achille*, Matthew Trager, Xiaolong Li, Jiawei Mo, Ashwin Swaminathan, CJ Taylor, Dheera Venkatraman, Xiaohan Fei*, and Stefano Soatto*. arXiv preprint, 2023.

This paper formalizes what it means to represent a physical scene, explains why NeRFs alone cannot extrapolate beyond observed data, and explores diffusion priors as a mechanism for constructing more general visual representations.

Single-camera physical distance estimates and safety visualization for pedestrians

Single View Physical Distance Estimation using Human Pose

Xiaohan Fei, Henry Wang, Xiangyu Zeng, Lin-Lee Cheong, Meng Wang, and Joseph Tighe. ICCV, 2021.

A direct pose-based formulation jointly estimates camera intrinsics, the ground plane, and distances between people from a fixed monocular camera, enabling metric measurements without manual calibration or range sensors.

Training pipeline for adaptive unsupervised depth completion

An Adaptive Framework for Learning Unsupervised Depth Completion

Alex Wong, Xiaohan Fei, Byung-Woo Hong, and Stefano Soatto. ICRA and IEEE Robotics and Automation Letters (RA-L), 2021.

The framework uses reconstruction residuals to adapt visibility and regularization weights across pixels and training time, improving existing unsupervised depth-completion methods without adding trainable parameters or inference cost.

Sparse visual-inertial points, planar scaffolding, and completed dense depth

Unsupervised Depth Completion from Visual-Inertial Odometry

Alex Wong*, Xiaohan Fei*, Stephanie Tsuei, and Stefano Soatto. ICRA and IEEE Robotics and Automation Letters (RA-L), 2020.

The method turns sparse visual-inertial landmarks into a piecewise-planar scaffold and learns dense depth through cross-modal photometric, pose, and geometric consistency; it also introduces the VOID dataset.

Geo-supervised depth-prediction training architecture using gravity and semantic priors

Geo-Supervised Visual Depth Prediction

Xiaohan Fei, Alex Wong, and Stefano Soatto. ICRA and IEEE Robotics and Automation Letters (RA-L), 2019. Best Paper Award in Robot Vision.

Gravity from inertial measurements and semantic shape priors supervise monocular depth during training, encouraging horizontal and vertical surfaces to follow known geometry and improving depth prediction across datasets.

Outdoor object-model detection and pose results from the VISMA system

Visual-Inertial Object Detection and Mapping

Xiaohan Fei and Stefano Soatto. ECCV, 2018.

An online monocular-inertial filter combines bottom-up detections with top-down object hypotheses to build a Euclidean map containing sparse geometry, recognized object models, and their poses; the work also introduces the VISMA dataset.

Construction and search of a hierarchical pooling structure for loop closure

A Simple Hierarchical Pooling Data Structure for Loop Closure

Xiaohan Fei, Konstantine Tsotsos, and Stefano Soatto. ECCV, 2016.

Hierarchically pooling temporally adjacent bag-of-words descriptors accelerates large-scale loop-closure search by 4–20× on average while preserving nearly the same retrieval performance as more costly schemes.

Professional Services

Reviewer for leading conferences in computer vision (CVPR, ICCV, ECCV), robotics (ICRA, IROS), and artificial intelligence (NeurIPS, ICLR, AAAI).

Talks & Workshops

Teaching