Ryosuke Ichikari

Ryosuke Ichikari

orcid

Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
29 December 2014 in ACM Transactions on Graphics
Verified
Journal Article
Open access
GFGraham Fyffe
Graham Fyffe
AJAndrew Jones
Andrew Jones
OAOleg Alexander
Oleg Alexander
RIRyosuke Ichikari
Ryosuke Ichikari
PDPaul Debevec
Paul Debevec
We present a process for rendering a realistic facial performance with control of viewpoint and illumination. The performance is based on one or more high-quality geometry and reflectance scans of an actor in static poses, driven by one or more video streams of a performance. We compute optical flow correspondences between neighboring video frames, and a sparse set of correspondences between static scans and video frames. The latter are made possible by leveraging the relightability of the static 3D scans to match the viewpoint(s) and appearance of the actor in videos taken in arbitrary environments. As optical flow tends to compute proper correspondence for some areas but not others, we also compute a smoothed, per-pixel confidence map for every computed flow, based on normalized cross-correlation. These flows and their confidences yield a set of weighted triangulation constraints among the static poses and the frames of a performance. Given a single artist-prepared face mesh for one static pose, we optimally combine the weighted triangulation constraints, along with a shape regularization term, into a consistent 3D geometry solution over the entire performance that is drift free by construction. In contrast to previous work, even partial correspondences contribute to drift minimization, for example, where a successful match is found in the eye region but not the mouth. Our shape regularization employs a differential shape term based on a spatially varying blend of the differential shapes of the static poses and neighboring dynamic poses, weighted by the associated flow confidences. These weights also permit dynamic reflectance maps to be produced for the performance by blending the static scan maps. Finally, as the geometry and maps are represented on a consistent artist-friendly mesh, we render the resulting high-quality animated face geometry and animated reflectance maps using standard rendering tools.

24 May 2021 in IEEE Sensors Journal
Verified
Journal Article
Open access
FPFrancesco Potortì
Francesco Potortì
Joaquín Torres-SospedraJoaquín Torres-Sospedra
Joaquín Torres-Sospedra
DQDarwin Quezada-Gaibor
Darwin Quezada-Gaibor
ARAntonio Ramon Jimenez Ruiz
Antonio Ramon Jimenez Ruiz
FSFernando Seco
Fernando Seco
HOHong Lye Oh
Hong Lye Oh
Every year, for ten years now, the IPIN competition has aimed at evaluating real-world indoor localisation systems by testing them in a realistic environment, with realistic movement, using the EvAAL framework. The competition provided a unique overview of the state-of-the-art of systems, technologies, and methods for indoor positioning and navigation purposes. Through fair comparison of the performance achieved by each system, the competition was able to identify the most promising approaches and to pinpoint the most critical working conditions. In 2020, the competition included 5 diverse off-site off-site Tracks, each resembling real use cases and challenges for indoor positioning. The results in terms of participation and accuracy of the proposed systems have been encouraging. The best performing competitors obtained a third quartile of error of 1 m for the Smartphone Track and 0.5 m for the Foot-mounted IMU Track. While not running on physical systems, but only as algorithms, these results represent impressive achievements.

21 July 2013
Verified
Conference Paper
Open access
OAOleg Alexander
Oleg Alexander
GFGraham Fyffe
Graham Fyffe
JBJay Busch
Jay Busch
XYXueming Yu
Xueming Yu
RIRyosuke Ichikari
Ryosuke Ichikari
JPJavier von der Pahlen
Javier von der Pahlen
Overview In 2008, the "Digital Emily" project [Alexander et al. 2009] showed how a set of high-resolution facial expressions scanned in a light stage could be rigged into a real-time photoreal digital character and driven with video-based facial animation techniques. However, Digital Emily was rendered offline, involved just the front of the face, and was never seen in a tight closeup. In this collaboration between Activision and USC ICT shown at SIGGRAPH 2013's Real-Time Live venue, we endeavoured to create a real-time, photoreal digital human character which could be seen from any viewpoint, in any lighting, and could perform realistically from video performance capture even in a tight closeup. In addition, we wanted this to run in a real-time game-ready production pipeline, ultimately achieving 180 frames per second for a full-screen character on a two-year old graphics card.

1 October 2015
Verified
Conference Paper
Closed access
RIRyosuke Ichikari
Ryosuke Ichikari
LRLuis Carlos Manrique Ruiz
Luis Carlos Manrique Ruiz
MKMasakatsu Kourogi
Masakatsu Kourogi
TKTakeshi Kurata
Takeshi Kurata
TKTomoaki Kitagawa
Tomoaki Kitagawa
SYSota Yoshii
Sota Yoshii
This paper presents a novel method for detecting the floor level of a smartphone user in an indoor environment based on the atmospheric pressure measured with sensors in the user's smartphone. Atmospheric pressure is one of the most informative factors when estimating altitude, because its relative variation has a strong correlation with changes in altitude. However, it is difficult to directly estimate the altitude based on an observation of the absolute pressure via smartphones, owing to individual differences in the sensors and changes in climate. In this paper, we propose a robust method for estimating the floor level by decomposing the observed pressure into three components. The first component is the change in altitude, and this component is the primary measure. The second is the global variation, such as changes in climate. The third concerns device-dependent variation. We utilize localization infrastructure, such as beacons or Wi-Fi access points, sparsely located in the environment, because such localization mechanisms can provide floor-level information. Exploiting this mechanism, time-series references to the pressure on each floor level can be generated collectively by aggregating readings from the pressure sensors of multiple users. Using these as a reference, each output of the pressure can be decomposed into device-specific offsets, environmental trends, and the altitude-dependent component. By extracting the altitude-dependent component, the floor level of the user can be estimated robustly without relying on fixed observations of atmospheric pressure.

23 May 2016
Verified
Conference Paper
Open access
PDF file
DCDan Casas
Dan Casas
AFAndrew Feng
Andrew Feng
OAOleg Alexander
Oleg Alexander
GFGraham Fyffe
Graham Fyffe
PDPaul Debevec
Paul Debevec
ASAri Shapiro
Ari Shapiro
Creating and animating realistic 3D human faces is an important element of virtual reality, video games, and other areas that involve interactive 3D graphics. In this paper, we propose a system to generate photorealistic 3D blendshape-based face models automatically using only a single consumer RGB-D sensor. The capture and processing requires no artistic expertise to operate, takes 15 seconds to capture and generate a single facial expression, and approximately 1 minute of processing time per expression to transform it into a blendshape model. Our main contributions include a complete end-to-end pipeline for capturing and generating photorealistic blendshape models automatically and a registration method that solves dense correspondences between two face scans by utilizing facial landmarks detection and optical flows. We demonstrate the effectiveness of the proposed method by capturing different human subjects with a variety of sensors and puppeteering their 3D faces with real-time facial performance retargeting. The rapid nature of our method allows for just-in-time construction of a digital face. To that end, we also integrated our pipeline with a virtual reality facial performance capture system that allows dynamic embodiment of the generated faces despite partial occlusion of the user's real face by the head-mounted display.

13 February 2019 in Sensors
Verified
Journal Article
Open access
PDF file
RIRyosuke Ichikari
Ryosuke Ichikari
KKKatsuhiko Kaji
Katsuhiko Kaji
RSRyo Shimomura
Ryo Shimomura
MKMasakatsu Kourogi
Masakatsu Kourogi
TOTakashi Okuma
Takashi Okuma
TKTakeshi Kurata
Takeshi Kurata
The performance of indoor localization methods is highly dependent on the situations in which they are used. Various competitions on indoor localization have been held for fairly comparing the existing indoor localization methods in shared and controlled testing environments. However, it is difficult to evaluate the practical performance in industrial scenarios through the existing competitions. This paper introduces two indoor localization competitions, which are named the “PDR Challenge in Warehouse Picking 2017” and “xDR Challenge for Warehouse Operations 2018” for tracking workers and vehicles in a warehouse scenario. For the PDR Challenge in Warehouse Picking 2017, we conducted a unique competition based on the data measured during the actual picking operation in an actual warehouse. We term the dead-reckoning of a vehicle as vehicle dead-reckoning (VDR), and the term “xDR” is derived from pedestrian dead-reckoning (PDR) plus VDR. As a sequel competition of the PDR Challenge in Warehouse Picking 2017, the xDR Challenge for Warehouse Operations 2018 was conducted as the world’s first competition that deals with tracking forklifts by VDR with smartphones. In the paper, first, we briefly summarize the existing competitions, and clarify the characteristics of our competitions by comparing them with other competitions. Our competitions have the unique capability of evaluating the practical performance in a warehouse by using the actual measured data as the test data and applying multi-faceted evaluation metrics. As a result, we successfully organize the competitions due to the many participants from many countries. As a conclusion of the paper, we summarize the findings of the competitions.