Mapping Images to Scene Graphs with Permutation-Invariant Structured Prediction

Machine understanding of complex images is a key goal of artificial intelligence. One challenge underlying this task is that visual scenes contain multiple inter-related objects, and that global context plays an important role in interpreting the scene. A natural modeling framework for capturing such effects is structured prediction, which optimizes over complex labels, while modeling within-label interactions. However, it is unclear what principles should guide the design of a structured prediction model that utilizes the power of deep learning components.

Yashraj Narang

I lead the Seattle Robotics Lab (SRL) in NVIDIA Research. Team members are experts in perception, task and motion planning, control, reinforcement learning, imitation learning, simulation, sim-to-real transfer, and VLAs. We take an AI, compute, and simulation-driven approach to solve some of the hardest problems in robotics.

Note: The Publications section below is incomplete. Please see Google Scholar for a complete list of publications and patents.

Interactive Stable Ray Tracing

Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-processing filters.

Light-Weight Protocols for Wire-Speed Ordering

We describe light-weight protocols for selective packet ordering in out-of-order networks that carry memory traffic.

Exploiting Idle Resources in a High-Radix Switch for Supplemental Storage

A general-purpose switch for a high-performance network is usually designed with symmetric ports providing credit-based flow control and error recovery via link-level retransmission. Because port buffers must be sized for the longest links and modern asymmetric network topologies have a wide range of link lengths, we observe that there can be a significant amount of unused buffer memory, particularly in edge switches. We also observe that the tiled architecture used in many high-radix switches contains an abundance of internal bandwidth.

Phantom Ray-Hair Intersector

We present a new approach to ray tracing swept volumes along trajectories defined by cubic Bézier curves. It performs at two-thirds of the speed of ray-triangle intersection, allowing essentially even treatment of such primitives in ray tracing applications that require hair, fur, or yarn rendering.

 

FocusAR: Auto-focus Augmented Reality Eyeglasses for both Real World and Virtual Imagery

We describe a system which corrects dynamically for the focus of the real world surrounding the near-eye display of the user and simultaneously the internal display for augmented synthetic imagery, with an aim of completely replacing the user prescription eyeglasses. The ability to adjust focus for both real and virtual stimuli will be useful for a wide variety of users, but especially for users over 40 years of age who have limited accommodation range.

A Closed-form Solution to Photorealistic Image Stylization

Photorealistic image stylization concerns transferring style of a reference photo to a content photo with the constraint that the stylized photo should remain photorealistic. While several photorealistic image stylization methods exist, they tend to generate spatially inconsistent stylizations with noticeable artifacts. In this paper, we propose a method to address these issues. The proposed method consists of a stylization step and a smoothing step.

Multimodal Unsupervised Image-to-Image Translation

Unsupervised image-to-image translation is an important and challenging problem in computer vision. Given an image in the source domain, the goal is to learn the conditional distribution of corresponding images in the target domain, without seeing any pairs of corresponding images. While this conditional distribution is inherently multimodal, existing approaches make an overly simplified assumption, modeling it as a deterministic one-to-one mapping. As a result, they fail to generate diverse outputs from a given source domain image. To address this limitation, we propose a Multimodal Unsupervised Image-to-image Translation (MUNIT) framework. We assume that the image representation can be decomposed into a content code that is domain-invariant, and a style code that captures domain-specific properties. To translate an image to another domain, we recombine its content code with a random style code sampled from the style space of the target domain. We analyze the proposed framework and establish several theoretical results. Extensive experiments with comparisons to the state-of-the-art approaches further demonstrates the advantage of the proposed framework. Moreover, our framework allows users to control the style of translation outputs by providing an example style image.

Localization-Aware Active Learning for Object Detection

Active learning - a class of algorithms that iteratively searches for the most informative samples to include in a training dataset - has been shown to be effective at annotating data for image classification. However, the use of active learning for object detection is still largely unexplored as determining informativeness of an object-location hypothesis is more difficult.