JP2003121745A - Reflecting surface designing method for imaging device and convex surface mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a reflecting surface shape of a convex surface mirror meeting user's demands and to provide an imaging device which can improve user's convenience. SOLUTION: Marginal light of the convex surface mirror 1 passes through a transparent cylinder 3 to impinge the convex surface mirror 1 and reflected light from its reflecting surface 1a is converged on a CCD 5b through a lens 5a and imaged circularly in a camera 5. The reflecting surface 1a of the convex surface mirror 1 is in not a known secondary curved surface shape, but an axially symmetrical shape and the shape of the reflecting surface 1a of the convex surface mirror 1 is designed through numerical integration based upon the relation between the radial direction position of an image on the imaging surface of the camera 5 and the angle of light impinging on the concave surface mirror 1 to the horizontal according to user's demands (projection relation with an object to be imaged).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus for forming an image of a circular shape on the image plane of reflected light from a convex mirror having an axially symmetric shape, and a reflecting surface of the convex mirror. To design the shape of the.

[0002]

2. Description of the Related Art As an image pickup apparatus having a simple structure for obtaining a circular image of a surrounding image on an image forming plane of a camera, there is one which uses a convex mirror having an axially symmetric shape with the optical axis of the camera as a central axis. Are known. In this type of image pickup device, the reflected light from the axisymmetric convex mirror is condensed into a circular shape on the image forming surface of the camera. As the surface shape (reflection surface shape) of such a convex mirror, a hyperboloid shape, a spherical shape, which is relatively easy to form,
Conventionally, it is general to adopt a known quadric surface shape such as a parabolic shape.

[0003]

In the conventional image pickup apparatus, since the surface shape (reflection surface shape) of the convex mirror is fixed to the quadric surface shape, the user can select the image pickup range, the image pickup target, the image pickup condition, and the like. There is a problem that it is not possible to reflect individual requests.

The present invention has been made in view of such circumstances, and it is possible to construct the surface shape (reflection surface shape) of the convex mirror which meets the user's request, and it is possible to sufficiently reflect the user's individual request, which is convenient. An object of the present invention is to provide an imaging device that can be improved and a method for designing a reflecting surface of a convex mirror for designing the surface shape of the convex mirror.

[0005]

An image pickup apparatus according to a first aspect of the present invention provides a convex mirror having an axially symmetric shape and a circular image by condensing light reflected by the convex mirror on its image forming surface through a lens. In an image pickup device including a camera to be obtained, a reflecting surface formed by numerical integration based on a linear function relationship between a radial position of an image on an image forming surface of the camera and a tilt of light incident on the convex mirror with respect to a predetermined direction. Is provided in the convex mirror.

An image pickup device according to a second aspect of the present invention comprises a convex mirror having an axially symmetric shape, and a camera for collecting light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. In the imaging device, the convex mirror has a reflecting surface formed by numerical integration based on a linear function relationship between an angle between a radial position of an image on an image forming surface of the camera and a predetermined direction of light incident on the convex mirror. It is characterized by having.

An image pickup device according to a third aspect of the present invention comprises a convex mirror having an axisymmetric shape, and a camera for collecting light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. In the image pickup apparatus, a projection method is applied in which the radial position of the image on the image formation plane of the camera and the inclination of the light incident on the convex mirror with respect to a predetermined direction have a linear function relationship.

An image pickup device according to a fourth aspect of the present invention comprises a convex mirror having an axisymmetric shape, and a camera for collecting light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. In the image pickup apparatus, a projection method is applied in which the angle between the radial position of the image on the image forming plane of the camera and the predetermined direction of the light incident on the convex mirror has a linear function relationship.

In the image pickup device according to the fifth aspect of the present invention, in any one of the first to fourth aspects of the invention, the radial position of the image on the image plane of the camera is set in consideration of the distortion of the lens. Is characterized by.

According to a sixth aspect of the present invention, there is provided a method for designing a reflecting surface of a convex mirror, comprising: a convex mirror having an axially symmetrical shape; and a camera for collecting light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. In a method of designing a reflecting surface of the convex mirror in an image pickup device including: a relationship between a radial position of an image on an image forming surface of the camera and a predetermined direction of light incident on the convex mirror is determined. The inclination of each of the plurality of points of the reflecting surface is obtained based on the determined relationship, and the shape of the reflecting surface is determined using the obtained inclination.

In the image pickup apparatus according to the first or third aspect of the invention, the relationship between the angle of the incident light on the convex mirror and the radial position of the image on the camera image plane is determined according to the projection relationship desired by the user. Based on this, the tilt at each point on the reflecting surface of the convex mirror is found so that the rate of change between the tilt of the incident light to the convex mirror with respect to the predetermined direction and the radial position of the image on the camera imaging surface is constant, and the found tilt The shape of the reflecting surface of the convex mirror is designed by the numerical integration of connecting the two. Therefore, it is possible to obtain the shape of the reflecting surface of the convex mirror that sufficiently reflects the user's wishes in the imaging range, the imaging target, the imaging conditions, and the like, and it is possible to obtain a use application, specifically, a projection relationship to a cylinder at infinity A circular image of the surrounding can be acquired.

In the image pickup apparatus according to the second or fourth aspect of the invention, the relationship between the angle of the light incident on the convex mirror and the radial position of the image on the camera image plane is determined according to the projection relationship desired by the user. Based on this, the tilt at each point of the reflecting surface of the convex mirror is found and calculated so that the rate of change between the angle formed by the incident light to the convex mirror and the predetermined direction and the radial position of the image on the camera imaging surface is constant. The shape of the reflecting surface of the convex mirror is designed by the numerical integration of connecting the tilts. Therefore, it is possible to obtain the shape of the reflecting surface of the convex mirror that sufficiently reflects the user's wishes in the imaging range, the imaging target, the imaging conditions, etc., and it is possible to obtain the shape depending on the use application, specifically, the projection relationship on a sphere with an infinite radius. A circular image of the surrounding area can be acquired.

In the image pickup device of the fifth invention, the shape of the reflecting surface of the convex mirror is designed in consideration of the distortion of the lens. Therefore, it is possible to eliminate the error caused by the distortion of the lens and obtain the shape of the reflecting surface of the convex mirror that better matches the user's request.

In the reflecting surface designing method of the convex mirror according to the sixth aspect of the invention, each point on the reflecting surface of the convex mirror is determined based on the relationship between the angle of the light incident on the convex mirror and the radial position of the image on the image plane of the camera. The tilt of the convex mirror is designed and the shape of the reflecting surface of the convex mirror is designed. Therefore, the imaging range, the imaging target,
It is possible to obtain the shape of the reflecting surface of the convex mirror that sufficiently reflects the user's request in imaging conditions and the like.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to the drawings showing the embodiments thereof. FIG. 1 is a diagram showing a configuration of an example of an image pickup apparatus of the present invention, and an image pickup apparatus 10 of the present invention includes a convex mirror 1, a support body 2, a cylindrical body 3, a connecting member 4, and a camera 5.

The convex mirror 1 is made of metal such as brass, and its base is attached to and supported by the support 2. Further, the reflecting surface 1a of the convex mirror 1 which is a feature of the present invention has an axisymmetric shape which is not a known quadric surface shape such as a hyperboloid shape, a spherical shape, or a parabolic shape, and the surface shape is used. It is designed according to the user's request (projection relationship with the imaging target). A design example of this surface shape will be described later in detail as a plurality of embodiments. The convex mirror 1 may be configured by providing a metal film of chromium, aluminum, silver or the like on the front surface or the back surface of the resin material.

The cylindrical body 3 is made of transparent glass or plastic, one end of which is fixed to the support 2 and
The other end side is fixed to the connecting member 4. The connecting member 4 includes a lens 5a, a CCD 5b, a lens barrel 5c, and a housing 5d.
A camera 5 equipped with, for example, is attached. Camera 5
And the symmetry axis of the convex mirror 1 coincide with each other. The lens 5a is fixed to the lens barrel 5c screwed to the inner peripheral surface of the housing 5d, and the position of the lens 5a in the optical axis direction is changed by adjusting the screwing position of the lens barrel 5c with respect to the housing 5d. It is possible to adjust the optical distance between the lens 5a and the CCD 5b to perform focusing.

With such a structure, the light around the convex mirror 1 strikes the convex mirror 1 through the cylindrical body 3 and its reflecting surface 1a.
The reflected light by is condensed on the CCD 5b via the lens 5a and is imaged by the camera 5.

FIG. 2 is a diagram showing the configuration of another example of the image pickup apparatus of the present invention. In FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals and their description is omitted. In this configuration example, the linear body 6 is fitted and fixed to the convex mirror 1 by protruding the tip end side of the convex mirror 1 on the axial extension of the convex mirror 1 toward the camera 5 side by a predetermined length.

Light from the circumferential direction about the optical axis of the camera 5 strikes the convex mirror 1 through the tubular body 3 and is condensed by the lens 5a of the camera 5 to obtain an image in the circumferential direction. The light reflected from the inner surface of the body 3 is reflected by the convex mirror 1 to the lens 5a of the camera 5.
It is conceivable that the accuracy of the acquired image may be reduced due to the light being condensed at. Therefore, in the configuration example shown in FIG. 2, the linear body 6 is provided in order to prevent this, that is, so that unnecessary reflected light is not guided to the camera 5 side. Light reflected by the inner surface of the cylindrical body 3 and reaching the convex mirror 1 will always cross the axial extension of the convex mirror 1 before being reflected by the inner surface.
By providing the linear body 6 at that position, all the light that is internally reflected and reaches the convex mirror 1 can be blocked by the linear body 6. Therefore, the accuracy of the acquired image can be improved.

With such a configuration, as in the configuration example shown in FIG. 1, the light around the convex mirror 1 strikes the convex mirror 1 through the cylindrical body 3, and the light reflected by the reflecting surface 1a is reflected by the lens 5
It is focused on the CCD 5b via a and is imaged by the camera 5. At this time, as described above, the linear body 6 is provided so that the internal reflection light of the cylindrical body 3 is not guided to the camera 5 side by the convex mirror 1, and the unnecessary internal reflection light is blocked by the linear body 6. To improve the accuracy of the acquired image.

FIG. 3 is a diagram showing an acquired image on the image plane of the camera 5 of the image pickup apparatus of the present invention having the configuration shown in FIG. 1 or 2, and a circular surrounding image is acquired.
Here, at which radial position (hereinafter, referred to as image forming height h) the reflected light at each point P of the reflecting surface 1a of the convex mirror 1 forms an image on the image forming surface of the camera 5 is determined at each point. P
Depends on the shape of the reflecting surface 1a.

Hereinafter, the reflecting surface 1 of the convex mirror 1 reflecting the user's request in the image pickup range, the image pickup object, the image pickup condition, and the like.
A specific design example of a will be described for each possible projection relationship.

(First Embodiment: Projection on Cylinder at Infinity) FIG. 4 is a diagram showing a projection relationship in the first embodiment. The direction of the arrow in FIG. 4 indicates the direction of projection onto the cylinder at an infinite position, and the light travels in the direction opposite to the direction of this arrow during actual imaging, and the reflecting surface 1 a of the convex mirror 1 is shown.
Is reflected by and is imaged on the camera 5.

This first embodiment is an example based on projection onto a cylinder at infinity, and is based on the inclination of the incident light (projection direction) on the reflecting surface 1a of the convex mirror 1 with respect to the horizontal direction. . This inclination e is obtained by e = tan θ, where θ is an angle formed by the incident light (projection direction) and the horizontal direction. This is an example in which the inclination e of the incident light (projection direction) is equally divided. In other words, the relationship between the inclination e and the image forming height h on the image forming surface of the camera 5 is a linear function. The first embodiment is suitable for obtaining a panoramic image, for example.

FIG. 5 is a flow chart showing the procedure of the design process of the shape of the reflecting surface 1a of the convex mirror 1 using the numerical integration in the first embodiment. First, the inclination e ₀ of the incident light (projection direction) to the reflecting surface 1a with respect to the horizontal direction when the image forming height of the camera 5 is 0 (h = 0) is determined (step S1). . Further, the inclination e = e ₁ when the image height is relatively high h = h ₁ (see FIG. 3) is determined (step S2). Using these determined parameters (e ₀ , h ₁ , e ₁ ), the following (1)
The relationship between the linear functions of e and h as shown in is determined (step S3). _{h / h 1 = (e-} e 0) / (e 1 -e 0) ... (1)

An arbitrary point P on the reflecting surface 1a is set (step S4). By connecting the set point P and the point O which is the center of the lens 5a, the image formation height h by the reflected light at this point P is obtained (see FIGS. 3 and 4) (step S).
5). From the obtained h, e is obtained according to the above (1) (step S6). The inclination (differential coefficient) of the reflecting surface 1a at the point P is determined so that the obtained h and e can be realized (step S7). The surface shape near the point P is obtained by slightly extending it with the determined inclination (step S8).

It is judged whether or not the entire shape of the reflecting surface 1a is obtained by this extension (step S9), and if not obtained (S9: NO), the next point P is added to the extension of the inclination. The setting is reset (S4), and the same processing (S4 to S8) is repeated. Then, when the entire shape of the reflecting surface 1a is obtained (S9: YES), the entire processing is ended. In this way, the entire reflecting surface 1a of the convex mirror 1 is obtained by numerical integration based on the relationship of the linear function of the image forming height h on the image forming surface 5 of the camera and the inclination e of the light incident on the convex mirror 1 with respect to the horizontal direction. The shape can be determined.

(Second Embodiment: Projection on Cylinder at Finite Distance) FIG. 6 is a diagram showing a projection relationship in the second embodiment. The second embodiment is an example based on the projection onto a cylinder at a finite position, and similarly to the first embodiment, the incident light (projection direction) on the reflecting surface 1a of the convex mirror 1 with respect to the horizontal direction. The tilt is used as a reference, and the relationship between this tilt and the image height on the image plane of the camera 5 is a linear function. Then, on the cylindrical surface K arbitrarily set by the user, the incident light becomes evenly spaced corresponding to the imaging heights that are equally spaced. The second embodiment is suitable for monitoring and imaging the inner surface of the tube, for example. The procedure of the design process of the shape of the reflecting surface 1a in the second embodiment is the same as in the case of the above-described first embodiment, and the description thereof will be omitted.

(Third Embodiment: Projection on a Plane at Infinity) FIG. 7 is a diagram showing a projection relationship in the third embodiment. This third embodiment is an example based on the projection onto a plane existing at infinity, and is based on the reciprocal of the inclination of the incident light (projection direction) on the reflecting surface 1a of the convex mirror 1 with respect to the horizontal direction. The reciprocal of this inclination is cotθ, where θ is the angle formed by the incident light (projection direction) and the horizontal direction.
This is an example in which the value of cotθ obtained by the above is equally divided. In other words, the relationship between this cot θ and the image formation height h on the image formation plane of the camera 5 is a linear function.

(Fourth Embodiment: Projection on a Plane at a Finite Distance) FIG. 8 is a diagram showing a projection relationship in the fourth embodiment. The fourth embodiment is an example based on projection onto a plane existing at a finite position, and similarly to the third embodiment, the incident light (projection direction) on the reflecting surface 1a of the convex mirror 1 with respect to the horizontal direction. The reciprocal of the inclination (cotθ) is used as a reference, and the relationship between the reciprocal of the inclination (cotθ) and the image formation height on the image plane of the camera 5 is a linear function. Then, on the plane L arbitrarily set by the user, the incident light becomes evenly spaced in correspondence with the imaging heights that are equally spaced.

The procedure for designing the shape of the reflecting surface 1a in the third and fourth embodiments can be performed in the same manner as in the case of the above-described first embodiment by substituting cotθ for the inclination e. Therefore, the description thereof is omitted.

(Fifth Embodiment: Projection on Sphere with Infinite Radius) FIG. 9 is a diagram showing a projection relationship in the fifth embodiment. The direction of the arrow in FIG. 9 indicates the direction of projection onto a sphere at an infinite position, and the light travels in the direction opposite to the direction of this arrow during actual imaging, is reflected by the reflecting surface 1a of the convex mirror 1, and is reflected by the camera 5. It is imaged.

The fifth embodiment is an example based on projection onto a sphere having an infinite radius, and the reflecting surface 1a of the convex mirror 1 is shown.
The angle θ of the incident light (projection direction) with respect to the horizontal direction is used as a reference. This is an example in which the angle θ is evenly divided. In other words, the relationship between the angle θ and the image forming height h on the image forming plane of the camera 5 is a linear function.

FIG. 10 is a flow chart showing the procedure of the design process of the shape of the reflecting surface 1a of the convex mirror 1 using the numerical integration in the fifth embodiment. First, when the image forming height of the image forming surface of the camera 5 is 0 (h = 0), the angle θ ₀ formed by the incident light (projection direction) to the reflecting surface 1a and the horizontal direction is determined (step S11). ). Further, the angle θ = θ ₁ when the image formation height is relatively high h = h ₁ (see FIG. 3) is determined (step S12). By using these determined parameters (θ ₀ , h ₁ , θ ₁ ), a linear function relationship of h and θ as shown in (2) below is determined (step S13). h / h ₁ = (θ−θ ₀ ) / (θ ₁ −θ ₀ ) ... (2)

An arbitrary point P on the reflecting surface 1a is set (step S14). By connecting the set point P and the set point O, the image formation height h by the reflected light at this point P is obtained (see FIGS. 3 and 9) (step S15). From the obtained h, θ is obtained according to the above (2) (step S16). The inclination (differential coefficient) of the reflecting surface 1a at the point P is determined so that the obtained h and θ can be realized (step S17).
The surface shape near the point P is obtained by slightly extending it with the determined inclination (step S18).

It is judged whether or not the entire shape of the reflecting surface 1a has been obtained by this extension (step S19), and if not obtained (S19: NO), the next point P is added to the extension of the inclination. Reset (S14) and perform the same processing (S14-
S18) is repeated. Then, when the entire shape of the reflecting surface 1a is obtained (S19: YES), the entire processing is ended. In this way, the reflection surface 1a of the convex mirror 1 is calculated by the numerical integration based on the linear function of the angle θ between the image forming height h on the image forming surface 5 of the camera and the horizontal direction of the light incident on the convex mirror 1. The overall shape of the can be determined.

(Sixth Embodiment: Projection on Sphere with Finite Radius) FIG. 11 is a diagram showing a projection relationship in the sixth embodiment. The sixth embodiment is an example based on projection onto a sphere having a finite radius, and similarly to the fifth embodiment, the horizontal direction of incident light (projection direction) on the reflecting surface 1a of the convex mirror 1 is the same. Is used as a reference, and the relationship between this angle and the image forming height on the image forming plane of the camera 5 is a linear function. Then, in the finite sphere M arbitrarily set by the user, the central angles of the incident light become equal intervals corresponding to the imaging heights at equal intervals. The procedure for designing the shape of the reflecting surface 1a in the sixth embodiment is the same as in the case of the fifth embodiment described above, and therefore the description thereof is omitted.

(Seventh Embodiment: Example of Projection on a Plane at Infinity and Blind Spot of Substantially Zero) FIG. 12 is a diagram showing a projection relationship in the seventh embodiment. In the seventh embodiment, a conical mirror 7 whose surface shape is a conical side surface is provided above the camera 5, and the reflective surface 1a is provided around the camera 5 by the user's request (imaging target). A convex mirror 1 having an axisymmetric reflecting surface 1a designed according to (projection relationship with) is provided. This convex mirror 1
Is, for example, similar to the third embodiment described above, so that the reflecting surface 1 thereof can be realized so as to realize a projective relationship on a plane at infinity.
The shape of a is designed.

In the seventh embodiment, the light travels in the direction opposite to the direction of the arrow shown in FIG. 12, and the reflecting surface 1a of the convex mirror 1
And is reflected twice by the surface of the conical mirror 7 to form an image on the camera 5. In the seventh embodiment, unlike the other embodiments described above, light from an angle near the optical axis of the camera 5 near 0 degrees can also be focused on the camera 5, and the diameter of the camera 5 can be reduced. When considering infinity by making it small, it is possible to eliminate the blind spots altogether.

By the way, the camera 5, especially its lens 5a
There is distortion in. Therefore, the camera 5 (lens 5
By considering the distortion of a), a more accurate shape of the reflecting surface 1a of the convex mirror 1 can be designed. As a method of considering this distortion, it is possible to add the distortion of the camera 5 (lens 5a) as a parameter when obtaining the imaging height h in the above-described flowcharts in FIGS. The image pickup height h ′ is obtained in consideration of the distortion of the lens 5a (lens 5a), and the obtained image height h ′ is used in the subsequent processing to obtain the camera 5 (lens 5a).
It is possible to design a more accurate shape of the reflecting surface 1a that compensates for the distortion.

[0042]

As described above, according to the present invention, the linear function of the radial position of the image on the image plane of the camera and the inclination or angle of the incident light on the convex mirror is calculated according to the projection relationship desired by the user. Since the shape of the reflecting surface of the convex mirror is designed by numerical integration based on the relationship, it is possible to construct an arbitrary shape of the reflecting surface of the convex mirror that meets the user's request, and improve the convenience of the user. .

Further, according to the present invention, the shape of the reflecting surface of the convex mirror is designed in consideration of the distortion of the lens. Therefore, the error due to the distortion of the lens is eliminated, and the convex mirror which is more suitable to the user's request is eliminated. The shape of the reflecting surface can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an image pickup apparatus of the present invention.

FIG. 2 is a diagram showing another configuration example of the image pickup apparatus of the present invention.

FIG. 3 is a diagram showing an acquired image on an image plane of a camera.

FIG. 4 is a diagram showing a projection relationship in the first embodiment.

FIG. 5 is a flowchart showing a procedure of design processing of the shape of the reflecting surface of the convex mirror in the first embodiment.

FIG. 6 is a diagram showing a projection relationship in the second embodiment.

FIG. 7 is a diagram showing a projection relationship in the third embodiment.

FIG. 8 is a diagram showing a projection relationship in the fourth embodiment.

FIG. 9 is a diagram showing a projection relationship in the fifth embodiment.

FIG. 10 is a flowchart showing a procedure of design processing of the shape of the reflecting surface of the convex mirror in the fifth embodiment.

FIG. 11 is a diagram showing a projection relationship in the sixth embodiment.

FIG. 12 is a diagram showing a projection relationship in the seventh embodiment.

[Explanation of symbols]

1 convex mirror 1a Reflective surface 5 camera 5a lens 5b CCD 6 linear objects 7 conical mirror 10 Imaging device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Maeda             3-8 Kasugadekita, Konohana-ku, Osaka City, Osaka Prefecture             4 Heights Sumire 201 (72) Inventor Nobuo Yamato             2-2-18 Shimodera, Naniwa-ku, Osaka-shi, Osaka             Within Stone Co., Ltd. F term (reference) 2H087 KA01 LA21 RA05 RA12 TA01                       TA03 TA06                 5C022 AC42 AC54 AC78

Claims (6)

[Claims] 1. An image pickup apparatus comprising: a convex mirror having an axially symmetric shape; and a camera that collects light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. The convex mirror has a reflecting surface having a shape obtained by numerical integration based on a linear function relationship between a radial position of an image on an image plane and a tilt of light incident on the convex mirror with respect to a predetermined direction. 2. An imaging device comprising: a convex mirror having an axially symmetric shape; and a camera that collects light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. The convex mirror has a reflecting surface having a shape obtained by numerical integration based on a linear function relationship between a radial position of an image on an image plane and an angle formed by a predetermined direction of light incident on the convex mirror. apparatus. 3. An imaging device comprising: a convex mirror having an axially symmetric shape; and a camera that collects light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. An image pickup apparatus, wherein a projection method in which a radial position of an image on an image forming surface and a tilt of light incident on the convex mirror with respect to a predetermined direction have a linear function relationship is applied. 4. An imaging device comprising: a convex mirror having an axially symmetric shape; and a camera that collects light reflected by the convex mirror on its image forming surface through a lens to obtain a circular image. An image pickup apparatus, wherein a projection method is applied in which a radial function of an image on an image plane and an angle formed by a predetermined direction of light incident on the convex mirror have a linear function. 5. The image pickup apparatus according to claim 1, wherein a radial position of an image on an image forming surface of the camera is set in consideration of distortion of the lens. 6. Reflection of the convex mirror in an image pickup device comprising a convex mirror having an axially symmetric shape and a camera for collecting light reflected by the convex mirror on its image plane through a lens to obtain a circular image. In the method of designing the surface, the relationship between the radial position of the image on the imaging surface of the camera and the angle formed by the predetermined direction of the light incident on the convex mirror is determined, and based on the determined relationship, the reflecting surface A method for designing a reflecting surface of a convex mirror, characterized in that the inclination at each of a plurality of points is obtained, and the shape of the reflecting surface is determined using the obtained inclination.