CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. § 371 of International Application No. PCT/JP2019/030333, having an International Filing Date of Aug. 1, 2019, which claims priority to Japanese Application Serial No. 2018-146591, filed on Aug. 3, 2018. The disclosure of the prior application is considered part of the disclosure of this application, and is incorporated in its entirety into this application.

TECHNICAL FIELD

The present invention relates to a virtual world construction system.

BACKGROUND ART

Conventionally, there are known virtual world construction systems for constructing a virtual world that a plurality of users can join, in a server on a network. For example, a multi-player online game is a game in which users play in a virtual world constructed by a virtual world construction system, and the users operate their alter egos (avatars) and other objects, which are present in the virtual world.

In this virtual world construction system, data regarding fixed objects among the objects with which the virtual world is constructed (for example, map data, structure data, avatar appearance data, etc.) is distributed to user terminals in advance. Each user terminal transmits information regarding user operations performed on an operation target such as an avatar, to a server. The server centrally manages the virtual world. The server computes, for each user terminal, the situation around the avatar in the virtual world, based on operation information received from the user terminal and fixed data distributed in advance, for example, and transmits variable data in the world around the avatar (for example, information regarding the positions of the other avatars and information regarding the positions of NPCs (Non Player Characters) around the avatar). Each user terminal renders images related to the virtual world and displays the images on the user terminal based on operation information regarding the avatar of the user, the fixed data distributed in advance, and the variable data received from the server, for example.

CITATION LIST

Non Patent Literature

[NPL 1] Gene Cheung and three other authors, “MULTI-STREAM SWITCHING FOR INTERACTIVE VIRTUAL REALITY VIDEO STREAMING”, 2017[NPL 1] Chen Gao and two other authors, “Concealing Jitter in Multi-Player Online Games through Predictive Behaviour Modeling”, Proceedings of the 2016 IEEE 20th International Conference Computer Supported Cooperative Work in Design, 2016

SUMMARY OF THE INVENTION

Technical Problem

In recent years, VR/AR (Virtual Reality/Augmented Reality) has become widespread, and is employed in terminals in a virtual world construction system. Recently, it is easy to experience VR by using an HMD (Head Mounted Display) on which an SoC (System on a Chip) is mounted, or by attaching a smartphone to an HMD type goggles. However, rendering performance and the quality of experience in such cases are poorer than those provided by high-end HMD products that use the latest expensive GPU (Graphics Processing Unit). Therefore, it is considered to simply realize high-end VR experience by transmitting video information rendered by a GPU in a remote data center to a lightweight terminal such as a smartphone.

In the above-described conventional virtual world construction system, the connection configuration in the application layer is of a star type, in which one server and a plurality of user terminals are connected to each other (seeFIG. 13(a)). Therefore, there is the following problem if rendering is performed by the server in the conventional virtual world system. That is to say, if user terminals are geographically dispersed, there is a problem in that, regarding a player using a user terminal that is away from the server in terms of communication distance, the virtual world delays changing in response to the player's actions, and there also is a delay in the provision of video.

Meanwhile, a distributed virtual world construction system has also been conceived of, in which the server does not centrally manage a virtual world, but instead each user terminal manages a virtual world. In this distributed virtual world construction system, the connection configuration in the application layer is of a mesh type in which user terminals are connected to each other in a peer-to-peer architecture (seeFIG. 13(b)). The user terminals exchange operation information regarding their avatars with each other, for example, and each user terminal manages a virtual world. That is to say, there are the same number of virtual worlds as the user terminals.

However, in a virtual world construction system with a mesh-type connection configuration, if user terminals are geographically away from each other, a delay or the like may occur, and if data loss or the like occurs during communication between user terminals, the respective virtual worlds of the user terminals may become inconsistent with each other. In order to prevent such a situation, each user terminal may perform a predictive action by predicting operation information regarding other users. However, depending on the degree of delay or loss, it is difficult to completely eliminate such inconsistencies between the virtual worlds. In addition, in this virtual world system, each user terminal performs rendering processing, and therefore there is a problem in that it is difficult to employ terminals with low computation capabilities such as those mentioned above.

With the foregoing in view, it is an object of the present invention to provide a virtual world construction system and method that do not impair consistency between virtual worlds and place only small loads on terminals.

Means for Solving the Problem

To achieve the above-described object, a virtual world construction system according to the present invention includes: a user terminal including operation information transmission means for transmitting operation information in a virtual world, and display means for displaying video information obtained by rendering the virtual world; a plurality of servers each including a computation unit that performs computation processing regarding a virtual world based on operation information received from the user terminal, and rendering processing means for generating video information by rendering the virtual world computed by the computation unit, and transmitting the video information to the user terminal; and a proxy that is located on a communication path between the user terminal and the servers, and relays operation information and video information, wherein the proxy includes operation information duplication means for transmitting operation information received from the user terminal, to the plurality of servers, by duplicating the operation information, and video integration means for transmitting timing information regarding the timing of rendering to the plurality of servers, and transmitting video information received from at least one of the servers, to the user terminal, and the rendering processing means of each of the servers performs rendering processing and video information transmission processing based on timing information received from the proxy.

Effects of the Invention

According to the present invention, rendering processing, through which a virtual world is visualized, is not performed by a user terminal, but is performed by a server. Therefore, it is possible to reduce the load on the user terminal. Also, according to the present invention, although virtual worlds are constructed by a plurality of servers, each server performs computations regarding a virtual world based on the same operation information, and each server performs rendering processing based on timing information transmitted from a proxy. Therefore, it is possible to improve consistency between virtual worlds.

Also, according to the present invention, virtual worlds are constructed by a plurality of servers, and a user terminal can receive video information rendered by a server that is located near the user terminal in terms of communication distance. Therefore, it is possible to improve the quality of experience. Also, according to the present invention, a plurality of servers construct virtual worlds and render video information. Therefore, it is possible to realize high availability and a high frame rate by enabling the servers to cooperate with each other.

