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Hung-Jui Guo

Assistant Professor of Computer Science

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About Me

Greetings! I'm an Assistant Professor at National Cheng Kung University in Taiwan, starting in December 2024. My research focuses on Extended Reality (XR), Human-Computer Interaction, Machine Learning, and Computer Vision. I aim to address common issues in virtual environments, such as depth perception and occlusion of collaboration objects over long distances.

I obtained my Ph.D. from The University of Texas at Dallas Software Engineering Department. where I was guided by Dr. Balakrishnan Prabhakaran. One of my primary working experiences during my Ph.D. has been working on an open project with the US Army Research Lab (ARL). This opportunity has helped me develop strong communication skills and collaborate effectively in a team setting.

I'm open to any research collaboration opportunities; please don't hesitate to contact me if you have any questions. Thank you!

Publications

CIDER: Collaborative Interactive Dynamic Environments for Mixed Reality

Hung-Jui Guo, Hiranya Garbha Kumar and Balakrishnan Prabhakaran

Submitted to: ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM), currently under review.

Mixed Reality system designed for long distance collaboration with Leader-Follower paradigm, integrating low-latency, dynamic, real-time 3D environment reconstruction of real-world scenes supporting object interactions in both real and virtual worlds.

CIDER Teaser Figure

Measuring Depth Perception for Color, Luminance, and Distance in Mixed Reality

Hung-Jui Guo, Laura R. Marusich, Jonathan Z. Bakdash, Shulan Lu, Andrew M. Tague, Reynolds, J. Ballotti, Derek Harter, Omeed Eshaghi Ashtiani and Balakrishnan Prabhakaran

Submitted to: IEEE International Conference on Multimedia & Expo (ICME) 2025, currently under review.

The current research reported a behavioral experiment with 59 participants that manipulated the color, luminance, and rendered distance of virtual objects in a Hololens 2 MR environment. The experiment examined the effects of these three variables on the human depth perception of the virtual objects. Results indicated that objects with cool colors (green and blue) tended to be perceived closer than objects with warm colors (red and yellow). Objects with high luminance tended to be perceived closer than low luminance ones. This is a unique result compared to previous related MR works.

Room2XR: Virtual Interactive Collaboration in Real-world Scenes

Hung-Jui Guo, Hiranya Garbha Kumar, Minhas Kamal and Balakrishnan Prabhakaran

Published at: Proceedings of the 32nd ACM International Conference on Multimedia (ACM MM'24).

This paper introduces Room2XR, a framework designed to dynamically reconstruct real-world scenes into virtual semantically similar representations using CAD models, and share them for remote collaboration. Room2XR employs advanced scene understanding technologies to create detailed virtual environments, enabling multiple users to interact with and manipulate these spaces in real time. By leveraging efficient algorithms and data transmission methods, Room2XR ensures accessibility and usability even on low-bandwidth networks.

Room2XR Paper Content

Improved Standard-Based Motion Parallax Measurement in Mixed Reality

Hung-Jui Guo and Balakrishnan Prabhakaran

Published at: IEEE International Conference on Multimedia Information Processing and Retrieval (MIPR) 2024

In this paper, we first propose an improved formula with normalization as a motion parallax evaluation standard and evaluate it by conducting motion parallax experiments using a Microsoft HoloLens 2 device. The experiments consisted of a standard one with different relative moving distances and distance reporting methods (blind walking and oral reporting), and another using an X-ray vision system that helps users see through physical obstacles, potentially providing motion parallax. The aim was to assess the effectiveness of our proposed standard and evaluate whether the proposed conditions influence users’ ability to estimate distance by utilizing motion parallax.

HoloLens 2 Technical Evaluation as Mixed Reality Guide

Balakrishnan Prabhakaran and Hung-Jui Guo

Published at: HCI International Conference 2024

Current citation number: 25

In this paper, we systematically evaluate the features that utilized sensors, including RGB cameras, eye cameras, depth cameras, and microphone array built in the Mixed Reality (MR) head-mounted device (HMD) – HoloLens 2 to show the progress compared to the previous HoloLens generation HMD. Moreover, we process and evaluate the accuracy of the data collected from the HoloLens 2 that incorporate Azure Spatial Anchor and research mode Inertial Measurement Unit (IMU) to show the innovations of this device. Based on the evaluation results, we provide discussion and suggestions for future researchers to design applications with existing capabilities.

Impact of motion cues, color, and luminance on depth perception in optical see-through AR displays

Omeed Eshaghi Ashtiani, Hung-Jui Guo and Balakrishnan Prabhakaran

Published at: Frontiers in Virtual Reality

We aim to perform an analysis of the effects of motion cues, color, and luminance on depth estimation of AR objects overlaying the real world with OST displays. We perform two experiments, differing in environmental lighting conditions (287 lux and 156 lux), and analyze the effects and differences on depth and speed perceptions.

User Evaluation of Dynamic X-Ray Vision in Mixed Reality

Hung-Jui Guo, Jonathan Z. Bakdash, Laura R. Marusich and Balakrishnan Prabhakaran

Published at: IEEE Conference on Virtual Reality and 3D User Interfaces 2023.

In this paper, we utilized the MR Head-Mounted Device (HMD) -- HoloLens 2 to build a virtual environment and a dynamic X-Ray vision window based on the created environment. Unlike the previous works, our system allows users to physically move and still have the X-Ray vision ability in real-time, providing depth cues and additional information in the surrounding environment. On top of it, we designed an experiment and recruited multiple participants as proof of concept for our system's ability.

Dynamic X-Ray vision extension Paper Content

Dynamic X-Ray Vision in Mixed Reality

Hung-Jui Guo, Jonathan Z. Bakdash, Laura R. Marusich and Balakrishnan Prabhakaran

Published at: Virtual Reality Software and Technology (VRST) 2022.

Current citation number: 4

In this paper, we demonstrate a dynamic X-ray vision window that is rendered in real-time based on the user's current position and changes with movement in the physical environment. Moreover, the location and transparency of the window are also dynamically rendered based on the user's eye gaze. We build this X-ray vision window for a current state-of-the-art MR Head-Mounted Device (HMD) -- HoloLens 2 by integrating several different features: scene understanding, eye tracking, and clipping primitive.

Dynamic X-Ray vision Paper Content

Augmented Reality and Mixed Reality Measurement Under Different Environments: A Survey on Head-Mounted Devices

Hung-Jui Guo, Jonathan Z. Bakdash, Laura R. Marusich and Balakrishnan Prabhakaran

Published at: IEEE Transactions on Instrumentation and Measurement (TIM), Impact Factor: 5.332.

Current citation number: 16

In this paper, we survey 87 environmental-related HMD papers with measurements from users, spanning over 32 years. We provide a thorough review of AR- and MR-related user experiments with HMDs under different environmental factors. Then, we summarize trends in this literature over time using a new classification method with four environmental factors, the presence or absence of user feedback in behavioral experiments, and ten main categories to subdivide these papers (e.g., domain and method of user assessment). We also categorize characteristics of the behavioral experiments, showing similarities and differences among papers.

AR/MR measurement categories

High-quality First-person Rendering Mixed Reality Gaming System for In Home Setting

Yu-Yen Chung, Hung-Jui Guo, Hiranya Garbha Kumar and Balakrishnan Prabhakaran

Published at: 2020 IEEE International Conference on Artificial Intelligence and Virtual Reality (AIVR). (2020)

Current citation number: 7

We created a Mixed Reality game using several RGB-D cameras to capture users' motion and texture onto the 3D human avatar in virtual environments. This game aims to exercise and relieve the pain of Phantom Pain. (Please read the abstract to find further information)
My main contribution to this paper is to transfer the texture from the frame to the image and mirror the texture to the missing limb.

First-person Rendering MR Gamimg System

Movie Genre Classification based on Poster Images with Deep Neural Networks

Wei-Ta Chu and Hung-Jui Guo

Published at: Workshop on Multimodal Understanding of Social, Affective and Subjective Attributes. (2017)

Current citation number: 76

We used movie posters as information to train the neural network model to help classify multiple movie genres. This work is a multi-label task that sets the movie classification foundation by using movie posters.
My main contribution to this work is collecting a large-scale movie poster dataset and building a custom neural network to classify movie genres by using the dataset.

This paper was my main research topic during my Master's degree.

Movie Poster Paper Content
More info on Google scholar

Work Experience

Assistant Professor - Department of Computer Science and Information Engineering, NCKU (12/2024 - Present)

Started as an Assistant Professor and held Multimedia and XR System Lab.

Post Doctoral Researcher - Mathematics Department, NTNU (09/2024 - 12/2024)

Worked with Dr. Tsung-Ming Huang on his 3D brain tumor segmentation problem.

Research Assistant - CS Department, UT Dallas (08/2021 - 12/2022)

Worked in the Collaborative Adaptive Augmented Reality Environment (CAARE) project in our lab and collaborated with Army Research Laboratory (ARL) team.
The current topic is related to HoloLens 2, scene understanding, and human behavior study.

Paper reviewer - ACM Multimedia 2023 (05/2023 - 05/2023)

Worked as a reviewer to review papers submitted to ACM MM 2023 by other researchers.

Paper reviewer - IEEE INTERNATIONAL CONFERENCE ON MULTIMEDIA AND EXPO 2022 (ICME) (01/2022 - 02/2022)

Worked as a reviewer to review papers submitted to ICME 2022 by other researchers.

Teaching Assistant - CS Department, UT Dallas (01/2020 - 08/2021, 01/2023 - 08/2024)

Worked as a Teaching Assistant in several different courses, such as Computer Science I, Software Engineering, Software Architecture and Design and Digital Logic and Computer Design.

Dean’s Office Assistant - College of Engineering, CCU (2014 - 2018)

Assisted college office assistant in delivering official documents and holding some events.

Part time job - Lenovo in COMPUTEX, Taipei (07/2015)

Worked as a part-time job in COMPUTEX to sell laptops and attract customers, and learned some new knowledge of laptops.

Awards and Honors

Jonsson School $1000 Graduate Study Scholarship - CS department, UT Dallas (2019)

Student Travel Grant - ACM Multimedia, Mountain View (2017)

Financial Support for Participating International Conferences - the Ministry of Science and Technology, Taiwan (2017)

Course and After-school Projects

After-school project

AI CUP 2020 - Aiwen Mango Three-Category Classification Competition (Fall 2020)

Building Machine Learning model for automatically classifying the quality of mangos and archive top 25% result.

Course project -- The University of Texas at Dallas

Advanced Software Engineering Project - APP - Air Pollutant Pathfinder (Spring 2023)

Constructing a navigation app to help users avoid potential harmful pollutants by utilizing multiple pollutant databases and navigation tools.

Introduction video available at: Air Pollutant Pathfinder

Requirement Engineering - SlimWalking (Spring 2020)

Design a project to help blind people navigating toward a target indoor location, including designing a vision document and a WRS document.

Database Design - DART bus database system design (Fall 2019)

Simulate a complete bus and customer database system by using Oracle and EER diagram.

Advanced Software Architecture and Design - NeGenSearch (Fall 2019)

Build a search engine algorithm and system by using crawler to craw websites and KWIC to create indices.