Three-dimensional stereoscopic image generation

1. A non-transitory, computer-readable information storage medium having stored therein a three-dimensional image generation program for generating, as images to be used for stereoscopic display, two images showing a scene within a virtual three-dimensional space viewed from two points of view, respectively, set in the virtual three-dimensional space, the three-dimensional image generation program causing a computer to function as:

parameter value acquisition unit configured to acquire a value of a screen distance parameter, which indicates a distance from a representative position for the two points of view to a virtual display screen in the virtual three-dimensional space, and configured to acquire a value of a perspective parameter, which indicates a degree of perspective in the stereoscopic display; and

three-dimensional image generation unit configured to generate, as the images to be used for the stereoscopic display, the two images showing the scene within the virtual three-dimensional space viewed from the two points of view disposed at positions and in directions that are determined based on the acquired value of the screen distance parameter and the value of the perspective parameter,

wherein the perspective parameter is a variable in the following mathematical expression:

r =( W ·tan α)/( I ·tan θ/2)

where r represents the perspective parameter and is limited to being between 0 and 1, I represents an interocular distance of a viewer of the stereoscopic display, θ represents a horizontal angle of view of a reference point of view, which defines a field of view of the stereoscopic display within the virtual three-dimensional space, W represents a width of a display screen on which the stereoscopic display is performed, and α represents an angle corresponding to half an angle defined by the directions of the two points of view.

2. The non-transitory, computer-readable information storage medium according to claim 1 , wherein:

the parameter value acquisition unit is configured to acquire a value of a parameter indicating a width of a display screen on which the stereoscopic display is performed; and

the three-dimensional image generation unit is configured to generate, as the images to be used for the stereoscopic display, the two images showing the scene within the virtual three-dimensional space viewed from the two points of view at positions and in directions that are determined based on the value of the screen distance parameter, the value of the perspective parameter and the value of the parameter indicating the width of the display screen.

3. The non-transitory, computer-readable information storage medium according to claim 1 , wherein the screen distance parameter is a variable in the following mathematical expression:

S·=i/ 2(tan α)

where S represents the screen distance parameter, i represents a distance between the two cameras, and α represents an angle corresponding to half an angle defined by the directions of the two cameras.

4. A three-dimensional image generation device configured to generate, as images to be used for stereoscopic display, two images showing a scene within a virtual three-dimensional space viewed from two points of view, respectively, set in the virtual three-dimensional space, the three-dimensional image generation device including a processor operating under the control of a computer program to implement functional units, comprising:

parameter value acquisition unit configured to acquire a value of a screen distance parameter, which indicates a distance from a representative position for the two points of view to a virtual display screen in the virtual three-dimensional space, and configured to acquire a value of a perspective parameter, which indicates a degree of perspective in the stereoscopic display; and

three-dimensional image generation unit configured to generate, as the images to be used for the stereoscopic display, the two images showing the scene within the virtual three-dimensional space viewed from the two points of view disposed at positions and in directions that are determined based on the acquired value of the screen distance parameter and the value of the perspective parameter,

wherein the perspective parameter is a variable in the following mathematical expression:

r =( W ·tan α)/( I ·tan θ/2)

where r represents the perspective parameter and is limited to being between 0 and 1, I represents an interocular distance of a viewer of the stereoscopic display, θ represents a horizontal angle of view of a reference point of view, which defines a field of view of the stereoscopic display within the virtual three-dimensional space, W represents a width of a display screen on which the stereoscopic display is performed, and α represents an angle corresponding to half an angle defined by the directions of the two points of view.

5. A three-dimensional image generation method of generating, as images to be used for stereoscopic display, two images showing a scene within a virtual three-dimensional space viewed from two points of view, respectively, set in the virtual three-dimensional space, the three-dimensional image generation method comprising:

acquiring a value of a screen distance parameter, which indicates a distance from a representative position for the two points of view to a virtual screen position in the virtual three-dimensional space;

acquiring a value of a perspective parameter, which indicates a degree of perspective in the stereoscopic display; and

generating, as the images to be used for the stereoscopic display, the two images showing the scene within the virtual three-dimensional space viewed from the two points of view disposed at positions and in directions that are determined based on the acquired value of the screen distance parameter and the value of the perspective parameter,

wherein the perspective parameter is a variable in the following mathematical expression:

r =( W ·tan α)/( I ·tan θ/2)

where r represents the perspective parameter and is limited to being between 0 and 1, I represents an interocular distance of a viewer of the stereoscopic display, θ represents a horizontal angle of view of a reference point of view, which defines a field of view of the stereoscopic display within the virtual three-dimensional space, W represents a width of a display screen on which the stereoscopic display is performed, and α represents an angle corresponding to half an angle defined by the directions of the two points of view.