JP2002039753A - Method for deciding photographing position for photogrammetry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow anyone to photograph for photogrammetry for wanted measurement precision. SOLUTION: A model of an object which is to be measured is generated in a 3DCAD space based on a design data (step S1), and a measurement point is marked at a required point (step S2). Three virtual photographing positions are set in the 3DCAD space (step S3). And photogrammetry where pictures taken at the positions are used is simulated to calculate measurement precision (step S4). The calculated measurement precision is compared with such measurement precision as wanted for actual photogrammetry (step S5), and if the former is lower than the latter the step S3 is visited again, for resetting the virtual photographing position, and then measurement precision is calculated in the step S4. If the former is higher than the latter, the virtual photographing position is decided to be a photographing position which is assured with measurement precision (step S6), and the data is outputted as a photographing position indicating report (step S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a photographing position for measuring a photograph so as to reliably obtain a desired measurement accuracy when performing a photograph measurement.

[0002]

2. Description of the Related Art For example, when a three-dimensional structure such as a bridge block or a hull block is manufactured, it is determined whether a portion to be accurately formed in these structures is formed as designed. In some cases, it may be desirable to measure the actual manufactured structure in order to confirm that the position of the hole is correct.In this case, a large, direct block such as the bridge block or hull block described above may be required. Photometry is one of the techniques used for measurement of structures for which it is difficult to measure dimensions.

[0003] This is because when a structure to be measured by an optical camera or a digital camera is photographed as an object to be measured,
If the dimensions of the image of the object to be measured projected on the film surface with an optical camera or on the CCD with a digital camera, the focal length of the camera, and the distance between the camera and the object to be measured are known. , Based on these dimensions and distances,
Using the fact that the actual dimensions of the measurement object can be calculated,
Based on a photograph of the object to be measured, the actual dimensions of each part of the object to be measured are obtained and measured.If the object to be measured is a three-dimensional structure, a plurality of images taken from different angles are taken. By using these photographs in combination, three-dimensional dimensions can be measured.

Incidentally, in such photo measurement, it is known that the measurement accuracy greatly varies depending on the photographing position (camera position and camera direction) at which the photograph to be used is taken, and the precision also varies depending on the number of photographs used. Has been
Therefore, it is very important to determine the photographing position, that is, to determine the camera installation positions for photographing the measurement object at different angles and to determine the direction of the camera at each camera installation position.

[0005]

However, conventionally, when determining the photographing position, the photographing angle and the number of photographs are examined while observing the object to be measured at the measurement site. The problem is that the measurement accuracy obtained by performing photo measurement depends on the photographing position examined by the measurer, and the determination depends on the intuition of the measurer, so that stable measurement accuracy is not guaranteed. In addition, there is a problem that the photographer is required to have experience in examining the photographing position, so that the number of photographers is limited, and it is not possible for anyone to measure the photograph.

[0006] Therefore, the present invention provides a photographing method capable of preliminarily determining and indicating a photographing position for photographing a photograph having a desired measurement accuracy so that anyone can take a photograph for photograph measurement. An object of the present invention is to provide a method of determining a measurement photographing position.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention sets a measurement point at which a photograph measurement is desired for a model created by importing design data of a measurement object into 3D CAD, Next, at least two virtual photographing positions capable of photographing the set measurement points were set in the 3D CAD space, and photograph measurement was performed based on the photograph photographed at each virtual photographing position. If the calculated measurement accuracy is lower than the measurement accuracy desired at the time of actual measurement, change the virtual photographing position or increase the virtual photographing position, and The measurement accuracy obtained when performing the photo measurement based on the photograph taken at the photographing position was calculated again, and the calculated measurement accuracy was equal to or higher than the measurement accuracy desired in the actual measurement. The case, a configuration to output the imaging position instruction that instructs the actual photography positions each virtual photography position.

In the 3D CAD space, when a virtual photographing position is set within an area where a measuring point set on a model of a measurement object can be photographed, a photograph taken at each virtual photographing position is set. The measurement accuracy obtained when performing photo measurement of the measurement target is calculated, and when the calculated measurement accuracy is lower than the measurement accuracy desired for actual photo measurement, a change in the virtual photo shooting position, or The measurement accuracy calculated by increasing the number of virtual photographing positions is improved, and each virtual photographing position is actually set only when the calculated measurement accuracy is calculated to be equal to or higher than the measurement accuracy desired for actual photograph measurement. Is output, so that a photograph is taken at the photographing position described in the photographing position instruction and a photo measurement is performed based on the photographed photograph. It is, measurement of the measurement object, it will be performed at a desired measurement accuracy over the measurement accuracy.

[0009] Further, the virtual photographing position is set while displaying the image observed through the viewfinder of the virtual camera arranged in the 3D CAD space on the monitor screen, so that the monitor screen is displayed. By setting the position of the virtual camera as the virtual photographing position while the measurement point is displayed, 3DCA
In the D space, the virtual photographing position can be easily set in the photographable area of the measurement point.

Further, the design data of the object to be measured is stored in 3DCA.
A measurement point at which a photo measurement is desired is set for the model created by taking the image on D, and then a measurement accuracy desired at the time of actual photo measurement of the measurement point is set.
Virtual photographing in which the measurement accuracy obtained when performing photo measurement based on a photograph of the measurement point in an area where the measurement point can be captured in the AD space is equal to or higher than the desired measurement accuracy By calculating the positions and setting two or more positions, and outputting a photographing position instruction sheet designating each of the set virtual photographing positions as an actual photographing position, the object to be measured in the 3D CAD space is obtained. Set measurement points on the model of
By simply inputting the desired measurement accuracy at the time of actual photograph measurement, it is possible to easily determine a photographing position for taking a photograph capable of performing photo measurement with a measurement accuracy higher than the desired measurement accuracy. .

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of a method for determining a photographing position for photograph measurement according to the present invention, and FIG. 1 shows a flow of an operation procedure.

First, the design data of the object to be measured is
D (three-dimensional CAD), and as shown in FIG.
In the DCAD space (virtual three-dimensional space on 3DCAD) 1, a model 2 (shown as a cube in the figure) of the object to be measured is created and displayed on the monitor screen 3 (step S).
1) For the model 2 of the measurement object displayed on the monitor screen 3, a measurement point 4 is set and marked at a place where photograph measurement is desired, for example, at a required place on the front of the model 2 (step S2). ).

Next, in the 3D CAD space 1, FIG.
As shown in (a), three virtual photographing positions 5a, 5b, and 5c are set in an area where the measurement point 4 marked on the model 3 can be photographed (step S3).
At this time, an image observed through a viewfinder of a virtual camera arranged at a required position in the 3D CAD space 1 is displayed on the monitor screen 3, that is, for example, as shown in FIG.
When the virtual camera 6 is arranged at the position 5a in (a), as shown in FIG. 3 (b), the model 2 of the measurement object is moved from the left front position through the viewfinder of the virtual camera 6. The observed image is displayed on the monitor screen 3, and when the virtual camera 6 is arranged at the position 5b in FIG.
As shown in (c), an image obtained by observing the model 2 from the front is displayed on the monitor screen 3. Similarly, when the virtual camera 6 is arranged at the position 5c in FIG. As shown in FIG. 3 (d), when an image of the model 2 observed from the right front position is displayed on the monitor screen 3, the image of the model 2 of the measurement object is rotated on the monitor screen 3. The relative position of the virtual camera 6 in the 3D CAD space 1 with respect to the model 2 can be changed.
By enlarging or reducing the size of the image of the model 2 above, the arrangement position of the virtual camera 6 in the 3D CAD space 1 can be made relatively closer or farther from the model 2, and further, the monitor screen By setting the measurement point 4 on the model 2 to be displayed on 3, the virtual camera 6 can be easily arranged in the area where the measurement point 4 can be photographed in the 3D CAD space 1. And the virtual photographing positions 5a, 5b, 5c
Can be easily set.

Next, a photograph obtained when the virtual camera 6 is arranged at each of the virtual photographing positions 5a, 5b, and 5c set in step S3 and photographed, that is, FIGS. 3B, 3C, and 3C (D) Simulate photo measurement using three photographs corresponding to the images on the monitor screen 3 as shown in (d), and calculate the measurement accuracy of the obtained measurement result (step S4). When performing the above simulation, it is assumed that the required noise is added to the logic used in the actual photo measurement so as to approximate the actual photo measurement.

Thereafter, the measurement accuracy calculated in step S4 is compared with the measurement accuracy desired by the measurer when performing actual photograph measurement (step S5), and the measurement accuracy calculated in step S4 is compared. If the measurement accuracy is lower than the measurement accuracy desired by the measurer, for example,
While we want to measure with measurement accuracy up to 05,
If the measurement accuracy calculated in step S4 is only up to 0.1, the process returns to step S3 to change the positions of the virtual photographing positions 5a, 5b, and 5c.
In addition to the existing virtual photographing positions 5a, 5b, and 5c, a new virtual photographing position is set so that the three virtual photographing positions can be set again or the number of photographs used for photograph measurement can be increased. After setting (not shown), the photograph measurement is simulated in the same manner as described above in step S4, and the obtained measurement accuracy is calculated.

If it is determined in step S5 that the measurement accuracy calculated in step S4 is equal to or higher than the measurement accuracy desired by the measurer, the process proceeds to step S6, where each virtual setting set in step S4 is performed. Photography position 5a,
After determining 5b and 5c as the photographing positions where the desired measurement accuracy is guaranteed, the above virtual photographing positions 5a and 5c are determined.
The information of 5b and 5c is output together with the information of the measurement point 4 to be photographed as a photographing position instruction for instructing the camera position and the direction of the camera (step S7). At this time, the photographing position instruction to be output is displayed on the monitor screen 3 when the virtual photographing positions 5a, 5b, 5c are set in step S3 in FIGS.
Is attached, that is, the image of the model 2 observed through the viewfinder of the virtual camera 6 arranged in the 3D CAD space 1 is attached, when viewed through the viewfinder of the camera at the time of actual shooting, By matching the image, it is possible to give a more specific instruction for the photograph to be taken.

Steps S3 to S5 are repeatedly performed to obtain the measurement points 4 in the 3D CAD space 1.
If the measurement accuracy calculated by the simulation performed in step S4 does not reach the desired measurement accuracy even after considering the set position of the virtual photographing position in the region where the image can be taken, the measurement point 4 is set to the photograph It is determined to be unsuitable for measurement and excluded from the measurement target (step S8).

As described above, in the photographing position instruction written in step S7, a photographing position that is previously guaranteed by simulation to obtain a measurement accuracy higher than a desired measurement accuracy in actual photograph measurement is specified. Therefore, by actually installing the camera based on the instructions of the above-mentioned shooting position instruction book and taking a photograph, it is possible to perform a photograph measurement of a desired measurement accuracy or more using the taken photograph, This eliminates the need to examine the photographing position while observing the measurement object at the measurement site, and allows anyone to easily take a photo for photo measurement without relying on the intuition of the measurer, Appropriate photo measurement work can be performed. Further, since the measurement point 4 for which it is known that the desired measurement accuracy cannot be obtained by the photo measurement can be excluded in advance from the measurement target in step S8, waste of the photo shooting operation can be eliminated.

FIG. 4 shows a flow of a work procedure according to another embodiment of the present invention.
After setting a measurement point 4 for which a photo measurement is desired for the model 2 of the measurement object created in the CAD space 1, a desired measurement accuracy when the photo measurement of the measurement point 4 is performed (the set measurement accuracy) A photographing position at which photograph measurement can be performed with the above-described measurement accuracy) is determined so that it can be output as a photographing position instruction sheet.

That is, similarly to the procedure of steps S1 and S2 in the above embodiment, a model 2 of a measurement object is created in the 3D CAD space 1 based on the design data of the measurement object. After the measurement point 4 is set for the model 2, a desired measurement accuracy is input when the photograph measurement is performed for the measurement point 4 (step S <b> 9). Based on the data of the measurement point 4 obtained, in a region where the measurement point 4 can be observed in the 3D CAD space,
When performing photo measurement, three or more virtual photo shooting positions capable of shooting a set of photos with a measurement accuracy higher than the desired measurement accuracy are calculated (step S10), and each calculated virtual photo shooting position is calculated. After the position is determined as the photographing position where the desired measurement accuracy is guaranteed (step S1)
1) The information of each virtual photographing position is output as a photographing position instruction for designating a camera position, a camera direction, and the like, together with the measurement point 4 to be photographed (step S12).

According to this embodiment, the same effects as those of the above embodiment can be obtained.
Within the measurement object model 2
By simply inputting the desired measurement accuracy at the time of actual photo measurement, the user can easily set a photographing position for taking a photo capable of performing photo measurement with a measurement accuracy higher than the desired measurement accuracy. Can be determined.

It should be noted that the present invention is not limited to only the above-described embodiment, and FIGS. 2 and 3 (a), (b), and (c).
In (d), the model 2 of the measurement object is shown as a cube. However, the measurement object can be applied to any shape, and one measurement object is placed in front of the model 2 of the measurement object in the 3D CAD space 1. Although the point 4 is shown as being set, the measuring point 4 may be set at any place on the model 2 as long as it can be observed from the outside. If possible, a plurality of measurement points 4 are set at the same time, and a set of photographing positions at which each of the measurement points 4 can perform photo measurement with a measurement accuracy higher than the desired measurement accuracy is determined. In FIG. 3 (a),
Set the virtual photographing positions 5a, 5b, 5c to be set to 3DC
Although the position is shown as being different in the horizontal direction in the AD space, virtual photographing positions different in position in the height direction are set in accordance with the shape of the model 2 of the measurement object and the setting position of the measurement point 4. In the stage of setting the measurement point 4 in the step S2, as shown in FIGS.
The image of the model 2 observed through the viewfinder of the virtual camera 6 arranged in the DCAD space 1 may be displayed on the monitor screen 3. In any of the above embodiments, the virtual photographing position is , Three or more positions are set, but this is because high measurement accuracy can be obtained when three or more positions are set. If the desired measurement accuracy is low, only two positions are set. Of course, various changes can be made without departing from the spirit of the present invention.

[0024]

As described above, according to the method for determining a photographing position for photograph measurement of the present invention, a model created by importing design data of an object to be measured into 3D CAD is used.
A measurement point at which photograph measurement is desired is set, and then at least two virtual photographing positions at which the set measurement point can be photographed are set in the 3D CAD space, and photographing is performed at each virtual photographing position. Calculating the measurement accuracy obtained when performing photo measurement based on the obtained photo, and if the calculated measurement accuracy is lower than the measurement accuracy desired at the time of actual measurement, change the virtual photographing position. Alternatively, the virtual photographing position is increased, and the measurement accuracy obtained when photograph measurement is performed based on the photographs taken at these virtual photographing positions is calculated again, and the calculated measurement accuracy is desired during actual measurement. When the measurement accuracy is equal to or higher than the measured accuracy, the photographing position instruction for designating each virtual photographing position as the actual photographing position is output.
In the D space, when a virtual photographing position is set within an area where a measuring point set on a model of a measurement target can be photographed, a photograph measurement performed based on the photograph taken at each virtual photographing position Is calculated by simulation, and if the calculated measurement accuracy is lower than the measurement accuracy desired for actual photograph measurement, the virtual photographing position is changed or the virtual photographing position is increased. It is possible to improve the measurement accuracy calculated by the above, and only when the calculated measurement accuracy is calculated as the desired measurement accuracy or more for the actual photo measurement, each virtual photo shooting position is set as the actual photo shooting position. Since it is possible to output the shooting position instruction to instruct, by actually installing the camera based on the instruction of the above shooting position instruction and taking a picture It is possible to perform photomeasurement beyond the desired measurement accuracy using the photographed photograph, thereby eliminating the need to examine the photographing position while observing the measurement object at the measurement site, and reduce the operator's Without relying on intuition, anyone can easily take pictures for photo measurement, and perform appropriate photo measurement work,
In addition, measurement points for which it is known that the desired measurement accuracy cannot be obtained by photo measurement can be excluded from measurement targets in advance, which has an excellent effect that waste of photo shooting work can be reduced. , And 3D on the monitor screen
With the configuration in which the virtual photographing position is set while displaying the image observed through the viewfinder of the virtual camera arranged in the CAD space, the virtual point is displayed in a state where the measurement points are displayed on the monitor screen. By setting the position of the camera as the virtual photographing position, the virtual photographing position can be easily set within the area where the measurement point can be photographed in the 3D CAD space. Is set on a 3D CAD model and a measurement point at which a photo measurement is desired is set. Next, a measurement accuracy desired at the time of actual photo measurement of the measurement point is set, and the measurement point in the 3D CAD space is set. Is obtained when a photo measurement is performed based on a photo taken of the above measurement point within the area where A virtual photographing position at which the measurement accuracy is equal to or higher than the desired measurement accuracy is calculated, two or more positions are set, and a photographing position instruction sheet indicating each of the set virtual photographing positions as an actual photographing position is output. With this configuration, in the 3D CAD space, a measurement point is set on the model of the measurement target, and a desired measurement accuracy is input at the time of actual photograph measurement. This makes it possible to easily determine a photographing position for photographing a photograph for which photograph measurement can be performed.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a method for determining a photographing position for photograph measurement according to the present invention, and is a diagram showing a flow of a work procedure.

FIG. 2 is a diagram illustrating an example of a model of a measurement target created in a 3D CAD space in step S1 of FIG. 1;

FIG. 3 schematically shows a case where a virtual photographing position is set in step S3 of FIG. 1;
The figure which shows arrangement | positioning of the virtual camera in D space, (b)
(C) and (d) are diagrams showing images displayed on the monitor screen when a virtual camera is located at each of the positions 5a, 5b, and 5c in (a).

FIG. 4 is a diagram showing a flow of a work procedure in another embodiment of the present invention.

[Explanation of symbols]

 1 3D CAD space 2 Model of object to be measured 3 Monitor screen 4 Measurement points 5a, 5b, 5c Virtual photographing position 6 Virtual camera

Claims (3)

[Claims] 1. A measurement point for which a photographic measurement is desired is set for a model created by importing design data of a measurement target onto a 3D CAD, and then at least two points at which the set measurement point can be photographed. Is set in the 3D CAD space, and a measurement accuracy obtained when a photo measurement is performed based on a photograph taken at each virtual photo shooting position is calculated, and the calculated measurement accuracy is calculated. If the measurement accuracy is lower than the measurement accuracy desired at the time of actual measurement, the virtual photographing position is changed or the virtual photographing position is increased, and photograph measurement is performed based on the photograph taken at these virtual photographing positions. The measurement accuracy obtained in the above case is calculated again, and when the calculated measurement accuracy is equal to or more than the measurement accuracy desired at the time of actual measurement, each of the virtual photographing positions is regarded as an actual photographing position. A method for determining a photographing position for photograph measurement, characterized by outputting a photographing position instruction sheet to designate. 2. The photographing apparatus according to claim 1, wherein a virtual photographing position is set while displaying an image observed through a viewfinder of a virtual camera arranged in a 3D CAD space on a monitor screen. How to determine the position. 3. A measurement point at which a photo measurement is desired is set for a model created by importing design data of a measurement object onto 3D CAD, and then a measurement accuracy desired at the time of actual photo measurement of the measurement point is set. And set 3DCAD
In a region where the measurement point can be photographed in space, a virtual photographing position at which the measurement accuracy obtained when performing photo measurement based on a photograph of the measurement point is equal to or greater than the desired measurement accuracy And calculating two or more locations, and outputting a photography position instruction for designating each set virtual photography position as an actual photography position.