JP2802781B2 - Evaluation method of positional relationship between two opposing surfaces by image processing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for evaluating the positional relationship between two opposing surfaces by image processing.

[Conventional technology]

For example, when two opposing surfaces are overlapped, it is necessary to adjust the mutual positional relationship.

Conventional optical alignment, as shown in FIG.
A mirror consisting of two parallel surfaces or a combination prism 14 having a similar function is interposed between the two opposite surfaces 12 and 13, two cameras 15 are installed on the same optical axis, and images of those cameras are displayed. This is done by matching the matching state.

[Problems of the prior art]

However, in such a method, since the position of the two cameras 15 is used as a reference, an error is likely to occur in the correspondence due to the influence of thermal deformation of the support frames of the two cameras 15 at the time of shooting, and an intermediate mirror or prism is used. Precise measurement has been difficult due to problems such as a position error such as 14 being indistinguishable from an error between two surfaces to be aligned.

[Object of the invention]

Therefore, an object of the present invention is to provide a method for correcting a positional error on a measuring instrument side such as a reflecting mirror or a camera and enabling a precise measurement.

[Solution of the Invention]

To achieve the above object, the present invention provides an image processing apparatus in which a mountain-shaped reflecting mirror is interposed between two opposing surfaces, and one camera is disposed on the vertex of the reflecting mirror. I send it to.

[Function of the invention]

One camera captures two images facing each other with the vertex ridgeline of the reflecting mirror as a boundary, and converts it into image data. This image data is stored inside the memory of the image processing apparatus. The image processing apparatus superimposes one image data on the other image data by reversing one image data on the image with the apex of the apex as an axis, and reversing the image data and the other image data Is checked, and the positional relationship between the two surfaces is evaluated based on the matched state.

In this evaluation method, a positional error of a reflecting mirror, a camera, and the like does not affect measurement accuracy, and a mutual positional relationship between two facing surfaces can be corrected in the field of image processing, so that accurate measurement can be performed. .

〔Example〕

FIG. 1 shows the configuration of the measurement system 1. In this embodiment, two opposing surfaces are a reference surface 2 and an alignment surface 3.
These are opposed to each other while facing each other.

The measurement system 1 is assembled by the reflecting mirror 4, the camera 5, and the image processing device 6.

The reflection mirror 4 has a mountain shape when viewed from the side, and the reference surface 2
And the positioning surface 3, and are incorporated so that the position can be adjusted in the direction of the arrow. The camera 5 is disposed on the vertex angle side of the reflecting mirror 4 and is substantially aligned on a line perpendicular to the ridgeline on a bisecting plane of the vertex angle. It is connected to the.
In this arrangement, the vertical or horizontal rows of light receiving elements (CCD elements) inside the camera 5 are set so as to be parallel to the bisecting plane of the apex angle of the reflecting mirror 4.

The image processing device 6 is assembled by a computer or the like, and is connected to the display device 8, the input device 9, and the like in addition to the memory device 7.

At the time of measurement, the camera 5 captures images of the reference plane 2 and the alignment plane 3 together with the ridge line of the reflecting mirror 4 and converts the image into one frame of image data. The image processing device 6 incorporates a program based on the method of the present invention, takes in image data from the camera 5, stores the image data at a predetermined address of the memory device 7, and then, as shown in FIG. Bordering on
By inverting one image data, for example, the image data corresponding to the alignment surface 3 with the vertex of the apex of the reflecting mirror 4 as an axis, the mirror is projected with the ridge as an axis.
After that, the image processing device 6 reads out the image data of the reference surface 2 bordering the ridge line and the image data of the alignment surface 3 after the inversion, sequentially compares the data in the scanning direction, for example, Take for example the AND condition. If the image data is exactly the same,
As shown in FIG. 3A, the front surface has one level, for example, a white level. However, if there is a shift in the image data, both images appear as black level data at the shift portion as shown in FIG. 3B. Therefore, the mutual positional relationship between the reference plane 2 and the alignment plane 3 can be evaluated in the field of image processing by confirming the matching state between the image data of the reference plane 2 and the alignment plane 3. Become.

According to this measuring method, the posture of the reflecting mirror 4 is removed by the function of inverting the image about the ridge line of the reflecting mirror 4 except for errors in the position and posture of the camera 5 and the inclination of the bisector of the reflecting mirror 4. And its position error can be avoided. As will be described later, the inclination of the bisecting surface of the reflecting mirror 4 can also be calculated based on the inclination of the ridge line in the captured image data by examining the direction of the ridge line in a normal state. Since the error can be corrected, the measurement accuracy does not decrease.
When the reference surface 2 and the positioning surface 3 are parallel to each other and the points to be measured on each surface are opposed to each other on the vertical line of the point, the vertex angle of the reflecting mirror 4 is set to 90 °. You. However, for example, when the point to be measured is located at a position deviated from the perpendicular, the shape of the reflecting mirror 4 is not a simple mountain shape.
Although the processing accuracy and positioning accuracy of the reflecting mirror 4 are easily affected, the effect of inversion can be obtained in the same manner.

4 to 12 show various measurement modes.

First, FIG. 4 shows the amount when the reflecting mirror 4 having a vertex angle of 90 ° is separated from the direction of the reference plane 2. In this case, since the image of the camera 5 moves only above or below the center as a whole, and there is no change in the correspondence relationship centering on the ridge line of both images, it can be evaluated by the same image processing.

Next, FIG. 5 shows a case where an error in the acute angle direction or the obtuse angle direction appears at the apex angle of the reflecting mirror 4. In this case as well, the image is compressed in the direction orthogonal to the ridge line with the ridge line as the center, or is simply expanded, and the ratio is the same. Therefore, the evaluation of the correspondence can be performed in the same manner as described above.

Further, FIG. 6 shows that the apex angle (θ = 45 °) of the reflecting mirror 4 is 2
An example is shown in which the equal plane is separated from the center line of the camera's intersection axis, is inclined by the angle α, and does not match. In this case, with respect to a normal screen, one surface is enlarged around the ridge line and the other surface is reduced. The enlargement or reduction ratio is obtained by the following equation.

L ₁ , L ₂ = L ₀ {tan (θ + α) −tan (2α)} This is a linear expression for a normal pitch, and by multiplying one by a coefficient (L ₁ / L ₂ ), one image data is obtained. And the other image data can be corrected to the same ratio.

Next, FIG. 7 shows a case where the reflecting mirror 4 is rotated by an angle β in any direction about the intersection axis of the camera 5. In this case, the screen projected on the normal screen is shifted by the inclination angle β. The shift amount at this time can be corrected by the following equation, where l is the distance from the reflecting mirror 4 to the light receiving surface from the camera 5.

Shift amount (correction amount) = ltan (± 2β) FIG. 8 shows a case where the reflecting mirror 4 is inclined in any direction in the horizontal plane. in this case,
An image after photographing is displayed on a normal screen in a tilting direction with the ridgeline as a center, but by inverting the ridgeline as a center, a correspondence can be obtained, so that no special correction is required.

Thus, various errors can be removed in the field of image processing by the self-correction function.

FIG. 9 shows a case where the various errors described above are corrected as necessary. In other words, the positioning reference surfaces 10 and 11 are arranged in a position facing each other at a position parallel to the facing reference surface 2 and positioning surface 3. At the time of alignment, the reflecting mirror 4 moves between the reference surfaces 10 and 11 and correctly faces the camera 5. The camera 5 uses these reference planes 1
By processing the images 0 and 11, the positional relationship is confirmed, and the position and error of the reflecting mirror 4 are corrected as necessary. Therefore, such assays are performed as needed within the measurement.

Next, FIG. 10 shows a case where the reference surface 2 and the positioning surface 3 face each other in a shifted state. In this case, the reflecting mirror 4 forms a reflecting surface facing each of the reference surfaces 2 or the positioning surfaces 3.

Further, FIG. 11 shows a case where the reference plane 2 and the positioning plane 3 are not parallel. In this case, the camera 5
It is arranged on the center line of the angle formed by the reference plane 2 and the alignment plane 3, and the apex angle of the reflecting mirror 4 is arranged so as to coincide with the optical axis. Even in this case, the same processing can be performed by regarding that the reference surface 2 and the positioning surface 3 face each other in a parallel state.

FIG. 12 shows a measurement example in the case where the reference plane 2 and the positioning plane 3 are not parallel and do not exist on the bisector. In this case, the same processing can be performed by using the reflecting mirror 4 having different angles with respect to the optical axis of the camera 5. Of course, the image may have the same size depending on the angle, but an error needs to be appropriately corrected in consideration of the angle.

〔The invention's effect〕

According to the present invention, in the process in which the camera takes images of the two reference planes and the alignment plane via the reflector, the image of the reference plane and the image of the alignment plane are line-symmetric with respect to the vertex of the reflector. In this state, the other image is inverted around the ridge line by image processing, thereby removing the position error and the attitude error of the camera itself, and the error of the inclination of the bisector of the reflecting mirror. Thus, errors in the attitude and position of the reflecting mirror can be avoided. Further, since two surfaces are simultaneously photographed by only one camera, there is no mutual positional error between the two cameras as in the related art.

[Brief description of the drawings]

FIG. 1 is a schematic side view of the measuring system of the present invention, FIG.
FIG. 3 is an explanatory view of a visual field, FIG. 3 is an explanatory view of a coincident state and a shifted state, FIGS. 4 to 12 are explanatory views of respective measurement modes, and FIG. 13 is a side view of a conventional example. DESCRIPTION OF SYMBOLS 1 ... Measuring system, 2 ... Reference plane, 3 ... Alignment plane, 4 ... Reflection mirror, 5 ... Camera, 6 ... Image information apparatus, 7 ... Memory apparatus, 8 ... Display, 9 ... ... Input device, 10, 11 ... Reference plane for alignment.

Claims (1)

(57) [Claims] 1. A mountain-shaped reflecting mirror is interposed between two opposing surfaces, and images of the two surfaces and a ridgeline of the apex angle are photographed by a camera on the apex side of the reflecting mirror and converted into an image. A method in which one image data is inverted around the ridge line of the apex angle as an axis, and a mutual positional relationship between the two surfaces is evaluated based on a coincidence state between the inverted one image data and the other image data. Evaluation method by image processing of the positional relationship between two surfaces to be performed.