Abstract Aggregation, as an operation of cartographic generalization, provides an effective means of abstracting the configuration of building features by combining them according to the scale reduction of the 2D map. Automating this design process effectively helps professional cartographers design both paper and digital maps, but finding the best aggregation result from the numerous combinations of building features has been a challenge. This paper presents a novel approach to assist cartographers in interactively designing the aggregation of building features in scale‐aware map visualization. Our contribution is to provide an appropriate set of candidates for the cartographer to choose from among a limited number of possible combinations of building features. This is achieved by collecting locally optimal solutions that emerge in the course of aggregation operations, formulated as a label cost optimization problem. Users can also explore better aggregation results by interactively adjusting the design parameters to update the set of possible combinations, along with an operator to force the combination of manually selected building features. Each cluster of aggregated building features is tightly enclosed by a concave hull, which is later adaptively simplified to abstract its boundary shapes. Experimental design examples and evaluations by expert cartographers demonstrate the feasibility of the proposed approach to interactive aggregation.

Color is an essential factor that influences human perception, and thus, the proper selection of color sets is crucial in creating informative and appealing visual content. Furthermore, the choice of such color palettes often reflects the underlying emotional intention of creators, especially when they want to introduce specific affective styles. This paper presents a color palette recommendation system that facilitates preferred colors and affective expressions in visual content. This is accomplished by introducing non-negative tensor factorization (NTF), which extends the conventional matrix-based collaborative filtering for recommending items through ratings of multiple users. In our approach, we composed a rating tensor that constitutes the scores for colors in terms of affective factors provided by participants in the user study. With this rating tensor, we explored the meaningful relation between affective expression and color preference. Our experiments exposed that we can successfully apply a tensor-based approach to recommending convincing sets of colors in several possible cases by predicting the underlying emotional intentions in the visual content design.

In recent years, with the spread of video streaming services and remote web conferencing systems, the increase in the number of end hosts connected to the Internet, the improvement of end host performance, and the diversification and sophistication of applications, the demand for communication quality of service (QoS) from users and service providers has become even higher. However, the amount of traffic flowing through the network is increasing year by year, and it has become difficult to operate a system that guarantees a certain level of QoS for users. In other words, best-effort type network systems have become the mainstream. Not only QoS, but also the user's own quality of experience (QoE) has become important, and application level control to improve user QoE within limited communication resources has become very important for both users and service providers. Since QoE is a subjective measure of a user's perception of a service, it is considered to be affected by cognitive biases that are observed in human subjective decision-making. In this paper, we conduct an experiment focusing on the choice-supportive bias, which is one of the cognitive biases, and clarify the effect of this cognitive bias on users during video viewing.

We present a 3D reconstruction system using RGB-D video. The key idea is to share both ends of RGB-D frames between adjacent subsequences. We implemented a novel 3D reconstruction system based on a conventional one, Open3D, and compared the conventional method to the system with the shared frames. We experimented with four datasets: three public datasets and one our proposed dataset. The our proposed dataset has quicker camera movement than the public datasets and is challenging to reconstruct. Our experiments demonstrate that our system reconstructs better synthetic scenes from the challenging dataset as the number of the shared frames increases and scenes from the other dataset retain reconstruction quality.

Our goal is to investigate different approaches to modulate stiffness and apply them to human-robot interaction. Here we report on our effort employing the concept of adjustable unsupported-length cantilever leaf spring, which has been previously applied to different designs of variable stiffness actuators. By transmitting the interaction force through the elastic component directly to the supporting structure instead of the actuation unit, this type of actuator requires low power to adjust and to maintain a desired stiffness. In the design of a 1-translational degree of freedom body weight support system of a rehabilitation robot, we used a leaf spring mechanism for stiffness modulation relying only on the spring deflection in combination with a non-backdrivable actuator for adjusting the vertical equilibrium position. This paper describes our approach in determining the spring parameters to attain a desired range of stiffness with a short traveling distance of the adjuster. To model the spring stiffness under deflection, the ideal cantilever support model cannot be assumed for a conventional design of dual roller-pairs slider, especially with a soft spring. A beam deflection model considering the non-zero slopes at the contact points between the rollers and the spring is presented, along with the validation experiments using different spring thicknesses on our prototype.

Daily living studies typically necessitate the use of a physical environment such as cameras, sensor networks, or experimental space. Moreover, it is difficult to collect data by flexibly changing the conditions. In the future, data from a physical space that can acquire real data and a virtual space that can easily change conditions and perform many experiments will need to be combined for analysis of daily life. This study proposes a framework for constructing and augmenting knowledge graphs (KGs) based on simulation results of daily living activities, using virtual space to enable various analyses of daily living activities. First, we design an ontology to represent virtual space activities and situational changes. Then, we construct KGs for the everyday living simulation. Second, we propose a method for KG augmentation that employs Markov chain to combine multiple activities KGs. Furthermore, we present several use cases using SPARQL queries and a KG embedding method. We also discuss the KG generation method, the proposed ontology, and the potential for expansion.

This paper proposes a novel method for accelerating ray tracing of animated scenes in which objects are moved, added, or deleted. The method uses two trees with different structures. The first tree is a hierarchical grid tree that is easily generatable from the primitive list and modifiable according to its change. The second tree is a bounding volume hierarchy (BVH) tree, constructed from the first tree with intra-node agglomerative clustering. When the scene is modified, the first tree is updated, and then, the second tree is partially rebuilt for accessed nodes in the first tree. The resulting BVH tree is deterioration-free; it always coincides with the tree generated by frame-wise rebuilding. For applications where a small portion of the scene is modified between frames, the tree formation cost of the proposed method is much lower than frame-wise rebuilding. Experiments showed that the quality of BVH trees generated by this method is comparable to those created by the binned surface area heuristic approach, and that the tree formation speed is faster not only for dynamic scenes but also for static scenes.

Bilateral teleoperation realizes tactile sensation transmission between distant places by realizing two control goals, which are synchronization of position response and the realization of the law of action and reaction. However, a communication delay between the systems deteriorates control performance of the whole system. Bilateral teleoperation that achieves simultaneity property, which is one of the control goals in bilateral control, was proposed by the authors. The system realizes to independently control position and force responses, which was not achieved in the conventional methods, by using a model of a delay time to buffer the force information. However, it is well known that delay time varies in network systems. Therefore, in this paper, control performance of the system in front of modeling error is analyzed and the effect caused by the error is compensated by using a phase-lead compensator. The compensation controller is designed to have enough phase margin and better position tracking performance. The validity of the proposed method is confirmed through experiments.

This paper proposes a novel method to realize simultaneity property and operational force reduction in a bilateral control system under communication delay. Bilateral control system realizes bilateral teleoperation with force sensation feedback to the operator, regarded as the next-generation communication tool transmitting force sensation. However, communication delay between the systems destabilizes the whole control system and the performance is also deteriorated. In this paper, the effect of the time delay is analyzed in a modal space, and considering that the operation is done by human, the interferences between the modal space is removed within the low frequency area that human operates by utilizing the buffered information. As for the stabilization purpose, phase-lag compensator is utilized. The validity of the proposed method is confirmed through experiments.

This paper proposes the best topology in multilateral control system. Multilateral control system is a control system which enables to share tactile information between several subsystems. Specifically, every subsystems communicates position and force information each other to achieve control goal. As shown above, the information flow is bilateral in multilateral control, and when sharing haptic information between several remote places, there occurs delay time in each communication links. When there exists delay time inside control system, the system starts to destabilize and haptic information deteriorates. In order to prevent the deterioration of the information, the optimal topology regarding position information is realized in this paper. The proposed method can be applied to a system where the delay time of each communication links is different from each other. The validity of the proposal is confirmed by experiments, and the results show that the degradation of haptic sensation under communication delay is prevented.

This paper proposes a backup system based on stackable mirroring filesystem "GMFS." We have developed GMFS to mirror data in realtime on the filesystem layer.GMFS uses NFS which is a typical network file system to communicate with an existing environment, and backup data to one or more NFS servers. Therefore, an existing empty resource can be used. It is necessary to backup data to two or more servers, considering the possibility that the backup data breaks. Moreover, the throughput of read and write has been improved by adopting the method to call system function of NFS from the inside of the filesystem.The result of the experiment from the viewpoint of throughput shows the following. The throughput of the read and write of GMFS is 2.4 times faster than conventional mirroring filesystem, and the decrease of throughput is a little even if the number of backup servers increases.

IP multicast technology enables simultaneous delivery of multimedia content to numerous users. However, the quality of experience (QoE) is subject to degradation due to packet loss because quality of service (QoS) is not guaranteed in best-effort IP networks. To maintain good QoE, streaming applications typically use an application-layer FEC (forward error correction) technique. Conventional FEC techniques always transfer redundant packets, but these redundant packets are only used when packet loss has occurred. This causes inefficiency in networks where packets are not often lost. To avoid filling network paths with unnecessary redundant packets, we developed a new application-layer packet loss recovery mechanism based on layered multicast using FEC and ARQ. This mechanism divides redundant packets into fundamental and supplementary redundant packet groups and sends them in separate multicast sessions. The supplementary redundant packets are received only by receivers participating in the multicast session of them or requesting retransmission. This mechanism realizes efficient reliable multicast for HDTV IP broadcasting by reducing unnecessary redundant packets and preventing an explosion of requests. We tested the effectiveness of our mechanism in streaming HDTV experiments over a commercial best-effort IP network. The results of experiment show that the proposed mechanism avoids transferring wasteful, redundant packets and efficiently maintains reliability with preventing an explosion of requests.

The VC-1 is a parallel graphics machine for polygon rendering based on image composition. This paper describes the architecture of the VC-1 along with a parallel polygon rendering algorithm for it. The structure of the VC-1 is a loosely-coupled array of 16 general-purpose processors, each of which is equipped with a local frame buffer. The contents of the local frame buffers are merged in real time for generating the final image. The local frame buffers are virtualized with a demand-paging technique, by which the image memory capacity for each local frame buffer is reduced to one eighth of full-screen capacity. Polygons are rendered in either pixel parallel or polygon parallel depending on the on-screen area of each polygon. The real performance of the VC-1 as well as estimated performance for systems with up to 256 processors is shown. CR