Optics: measuring and testing – Position or displacement
Reexamination Certificate
1999-09-29
2004-04-06
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Position or displacement
C396S014000, C250S483100, C348S137000
Reexamination Certificate
active
06717683
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a target for use in a photogrammetric analytical measurement system, in which a survey map is produced on the basis of a set of photographed pictures obtained at two different photographing positions.
2. Description of the Related Art
For example, photogrammetry is carried out at a traffic accident spot. The traffic accident spot is photographed by a camera in at least two different positions, and a survey map of the traffic accident spot is produced based on a set of photographed pictures obtained at the different positions.
In particular, a two-dimensional coordinate system is defined on each of the photographed pictures, and two-dimensional positions of the objects, which are recorded on each picture, are determined by the two-dimensional coordinate system. Then, a three-dimensional coordinate system is defined on the basis of the two sets of two-dimensional coordinate systems, and three-dimensional positions of the recorded objects are determined from the three-dimensional coordinate system. Accordingly, it is possible to produce a survey map of the traffic accident spot by drawing the objects on a sheet of paper in such a manner that the objects are projected on one of the three planes defined by the three-dimensional system.
Before accurately scaled distances and lengths can be reproduced on the survey map, a standard measurement scale must be recorded together with the objects in the photographed pictures. Also, a standard reference plane, on which the survey map should be drawn, must be defined in the photographed pictures.
Usually, in order to define the standard measurement scale and the reference plane, three respective cone-shaped markers, which are identical to each other, are positioned at suitable locations around a traffic accident spot. Namely, a distance between two apexes of the cone-shaped markers is measured, for example, with a measuring tape, and set as the standard measurement scale, and a plane, defined by the three apexes of the cone-shaped markers, is utilized as the reference plane. As the positioning of the cone-shaped markers and the measurement of the distance between the two apexes are performed by operators, a process of preparing for photographing is onerous and requires a lot of time.
In order to solve the above mentioned problems, photogrammetric analytic measurement, using a target which has a triangular frame instead of the three cone-shaped markers, is disclosed in Japanese Unexamined Patent Publication (Kokai) No. P10-170263. Standard point members are respectively mounted on each of three apexes of the target. A distance between the standard point members is set as the standard measurement scale, and a plane defined by the standard point members is utilized as the reference plane. A reflecting sheet, for example, is attached on the standard point members so that the standard point umbers can be viewed easily in photographed pictures.
However, if photogrammtric analytic measurement is performed under condition in which an amount of luminance is not ideal for photographing, for example, in rain or at nighttime, or at a spot, in which a surface of a road reflects incident light, the standard point members can not be viewed clearly in photographed pictures. Accordingly, the standard measurement scale and the reference plane are not accurately determined, and thus the photogrammetric analytic measurement can not be performed accurately.
The determination of the three-dimensional positions of the recorded objects from the three-dimensional coordinate system is carried out by iterating a series of approximate calculations, using a computer having a monitor on which the set of photographed pictures is displayed.
Initially, before a first series of approximate calculations is executed, the apexes of the cone-shaped markers and a suitable point on one of the recorded objects in the set of photographed pictures displayed on the monitor are selected with a cursor, by manipulating a mouse, whereby three sets of two-dimensional coordinates, corresponding to the apexes of the cone-shaped markers, and a set of two-dimensional coordinates on the suitable point of the selected object are inputted to the computer. Namely, the execution of the first series of approximate calculations is based upon the inputted two-dimensional coordinates of the apexes of the cone-shaped markers and the inputted two-dimensional coordinates of the suitable point on the selected object, thereby determining three-dimensional positions of the apexes of the cone-shaped markers and a three-dimensional position of the suitable point of the selected object from the three-dimensional coordinate to system.
Then, another suitable point on the selected object in the set of photographed pictures displayed on the monitor is indicated with the cursor, by manipulating the mouse, whereby a set of two-dimensional coordinates of the other suitable point on the selected object is inputted to the computer, and a second series of approximate calculations is executed on the basis of the inputted two-dimensional coordinates of the other suitable point on the selected object, thereby determining a three-dimensional position of the other suitable point on the selected object from the three-dimensional coordinate system. This procedure is continued until a sufficient number of points on the selected object are indicated, to thereby specify a three-dimensional profile of the selected object.
The aforementioned series of approximate calculations is executed based on positional data of the camera at which the pictures are photographed. The positional data of the camera includes a distance from the camera to the selected object, an angle of the camera against the object. Accordingly, at the traffic accident spot, it is necessary for an operator to measure and record such positional data.
However, it is onerous to measure the positional data of the camera every time a picture is photographed. Further, the measurement of the positional data of the camera requires a great deal of time and labor. On the other hand, the photogrammetry at the traffic accident is required to be rapidly performed. Accordingly, it is difficult to obtain an accurate positional data of the camera at a photogrammetry spot, such as the traffic accident spot.
Further, before the three-dimensional profile of the selected object can be properly specified and produced, each of the suitable points on the selected object must be precisely indicated with the cursor, by an operator's manipulation of the mouse. Nevertheless, the indication of the suitable points on the selected object with the cursor, by the operator's manipulation of the mouse, cannot always be carried out in a precise manner. Of course, unless the precise indication of the suitable points on the selected object can be ensured, the selected object cannot be accurately drawn on the survey map Namely, sufficient work efficiency and accuracy of the photogrammetry can not be obtained.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a target for photogrammetry, by which positional data of a camera is calculated based on a photographed picture by photographing an object therewith.
In accordance with an aspect of the present invention, there is provided a target for photogrammetric analytic measurement, which is photographed with an object by a camera in the photogrammetric analytic measurement, the target having standard points that are clearly discerned in a photographed picture, and a calculation of photographing positions of the camera being performed by determining a positional relationship of each of the standard points in the photographed pictures, the target comprising: a first standard point member defining a first standard point included in the standard points; a second standard point member defining a second standard point included in the standard points; a third standard point member defining a third standard point included in the standard poin
Hara Masato
Kaneko Atsumi
Kida Atsushi
Nakayama Toshihiro
Shirai Masami
Font Frank G.
Greenblum & Bernstein P.L.C.
Nguyen Sang H.
PENTAX Corporation
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