JP5469756B1 - Step measurement method, step measurement support device, step measurement support program, recording medium - Google Patents

Abstract

A method for safely and inexpensively measuring a manhole step is provided.
A step measurement method includes a digital image acquisition step S110, a depression angle calculation step S120, a unit length calculation step S130, and a step calculation step S140. The depression angle calculating step obtains a value corresponding to the number of long diameter dots in the digital image and a value corresponding to the number of short diameter dots for the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid. Then, the value corresponding to the depression angle when the manhole is photographed is calculated. The unit length calculation step S130 calculates the relationship between the value corresponding to the number of dots and the actual length from the value corresponding to the number of long-diameter dots and the actual manhole size. The step calculation step S140 obtains a value corresponding to the number of bits in the minor axis direction in the digital screen on the inner surface or outer surface of the manhole frame, and calculates a value corresponding to the depression angle, a value corresponding to the number of dots, and an actual value. The actual length is calculated using the relationship with the length.
[Selection] Figure 8

Description

  The present invention relates to a step measuring method, a step measuring support device, a step measuring support program, and a recording medium for measuring a step of a manhole.

  Patent Document 1 and Patent Document 2 are known as methods for efficiently measuring road facilities. Japanese Patent Application Laid-Open No. 2004-151561 discloses a technique for efficiently measuring road facility information using GPS by performing three-dimensional analysis on image data captured on a vehicle using a plurality of digital cameras. Patent Document 2 is a technique for measuring a road surface state by providing a vehicle with two displacement meters and an odometer.

  The subject of the measurement of the present invention is a manhole installed on a road (including a roadway, a sidewalk, etc.). In the case of a manhole, if there is a step or rattle between the lid and the frame, the lid is affected by the impact when the vehicle passes. May open (jump out of the frame), or may obstruct pedestrians and bicycles. In particular, in the case of a roadway, even a level difference of about 5 mm may cause a problem. Therefore, it must be measured with higher accuracy than the level of measurement on a general road surface. Therefore, the operator manually measured the level difference of the manhole using calipers or the like.

JP 2003-139533 A JP-A-6-94445

  In order to manually measure the manhole level difference, a measurement time that hinders traffic is required. It was also dangerous when the manhole was on the road. The techniques disclosed in Patent Documents 1 and 2 require a high-precision measuring device to perform delicate measurements on manholes, which is not realistic in view of cost and the like. SUMMARY OF THE INVENTION An object of the present invention is to provide a technique for measuring a manhole level difference safely and inexpensively.

  The step measuring method for measuring a step of a manhole according to the present invention includes a digital image acquisition step, a depression angle calculation step, a unit length calculation step, and a step calculation step. In the digital image acquisition step, a digital image of a manhole expressed by a set of dots is acquired. Here, “acquisition” includes photographing and printing out. The depression angle calculating step obtains a value corresponding to the number of long-diameter dots in the digital image and a value corresponding to the number of short-diameter dots for the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid, The value corresponding to the depression angle when the manhole in the digital image is photographed is calculated. Note that the value corresponding to the number of dots may be the number of dots in the image at the time of shooting, may be a value corrected by enlarging or reducing the digital image, or may be the length on the printed paper. It is an expression for indicating that another unit value corresponding to the number of dots may be used. In addition, the value corresponding to the depression angle may be the depression angle itself, or the sine or cosine of the depression angle. In the unit length calculation step, the relationship between the value corresponding to the number of dots and the actual length is calculated from the value corresponding to the number of long-diameter dots and the actual manhole size. In the step calculation step, a value corresponding to the number of bits in the minor axis direction in the digital screen on the inner surface or outer surface of the manhole frame is obtained, and a value corresponding to the depression angle, a value corresponding to the number of dots, and an actual length are calculated. The actual length is calculated using the relationship between

The step measurement assisting apparatus of the present invention has an image display means, an operation means, and a recording means for recording manhole dimension information, and supports the measurement of manhole steps. The level difference measurement support apparatus of the present invention includes a digital image acquisition unit, a depression angle calculation unit, a unit length calculation unit, and a level difference calculation unit. The digital image acquisition unit acquires a digital image of a manhole expressed by a set of dots. “Acquisition” here means acquiring electronic data of a digital image. The depression angle calculation part
(a1) Display a digital image of a manhole and a rectangular cursor on the image display means,
(a2) Have the operator adjust the position and size of the cursor so that the rectangle touches the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid using the operating means,
(a3) A value corresponding to the number of dots on the long side of the rectangle and a value corresponding to the number of dots on the short side in the digital image for the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid A value corresponding to the number of dots of the long diameter and a value corresponding to the number of dots of the short diameter,
(a4) A value corresponding to the depression angle when the manhole in the digital image is photographed is calculated from the value corresponding to the obtained long diameter dot number and the value corresponding to the short diameter dot number. The unit length calculation unit calculates the relationship between the value corresponding to the number of dots and the actual length from the value corresponding to the number of long-diameter dots and the information on the size of the manhole recorded in the recording means. The step calculator is
(b1) Display a manhole digital image and a pointer to indicate two positions on the image display means,
(b2) The operator uses the operating means to place the pointers at both ends in the minor axis direction of the inner surface or outer surface of the manhole frame in the digital screen,
(b3) Find the value corresponding to the number of bits between the two pointers,
(b4) The actual length of the inner or outer surface is calculated using the value corresponding to the depression angle and the above relationship.

  According to the step measurement method of the present invention, since a digital image of a manhole can be taken and then the step can be measured using the acquired digital image, manual work is not required, and the manhole step can be measured safely at low cost. be able to. Moreover, according to the level | step difference measurement assistance apparatus of this invention, the person can perform easily the level | step difference measuring method of this invention.

The top view of the cover part of a general manhole. The side view of the manhole containing the cross section in the AA of FIG. The enlarged view of the part of B of FIG. The figure which shows the state of the manhole which passed through years after installation. The figure which added the line and symbol which show a dimension for description to the digital image of a manhole. The figure which shows a mode when the manhole 1 is image | photographed with the camera 700. FIG. The figure which expanded the part of the manhole 1 of FIG. The figure which shows the flow of the level | step difference measuring method of this invention. The figure which shows the function structural example of the level | step difference measurement assistance apparatus of this invention. The figure which shows throw of the level | step difference measuring method at the time of using a level | step difference measurement assistance apparatus. The figure for demonstrating step S121. The figure for demonstrating step S122. The figure for demonstrating step S141. The figure for demonstrating step S142.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, the same number is attached | subjected to the structure part which has the same function, and duplication description is abbreviate | omitted.

<Characteristics and principle of measurement object>
1 is a plan view of a cover portion of a general manhole, FIG. 2 is a side view of the manhole including a cross section taken along line AA in FIG. 1, and FIG. 3 is an enlarged view of a portion B in FIG. The lid portion of the manhole is composed of a lid 10 and a frame 20. In addition, in this application, since the inside of a manhole is not mentioned, the cover 10 and the frame 20 are collectively expressed as the manhole 1. Further, usually, the lid is provided with a pattern for preventing slipping, but it is omitted in the drawing of the present application. The lid 10 is composed of a lid body 11, a lid surface 12, a lid contact surface 13, a rubber packing 14, and the like. The frame 20 includes a frame main body 21, a frame surface 22, a lid support surface 23, a rubber packing support surface 24, an inner side surface 251, an outer side surface 252, and the like. In FIG. 1, D1 is the outer diameter of the frame surface, D2 is the inner diameter of the frame surface, and D3 is the outer diameter of the lid. 2 and 3, 900 is a road, and a dotted line indicates a road surface 920. There are several types of manholes 1, but the lid 10 is almost circular in order to prevent falling, and the dimensions are determined for each type. Further, since the type can be identified by checking the equipment record, the diameter D1 of the outer periphery of the frame surface, the diameter D2 of the inner periphery of the frame surface, and the diameter D3 of the outer periphery of the lid are known. At the time of installation, the manhole cover surface 12, the frame surface 22, and the road surface 920 are at the same height.

  FIG. 4 is a diagram illustrating a state of a manhole that has passed through the years since installation. For example, in the case of a manhole installed on a roadway, a large vehicle passes many times, so that a step S1 occurs between the lid surface 12 and the frame surface 22 due to wear of the lid contact surface 13 and the lid support surface 23. Further, a step S2 is also generated between the road surface 920 and the frame surface 22 due to wear of asphalt or concrete. Furthermore, if there is rattling between the lid contact surface 13 and the lid support surface 23, the lid 10 may jump out of the frame 20 with the momentum when the vehicle passes, and the manhole may be opened. Further, when removing snow with a snowplow, the step S2 may become an obstacle. Furthermore, when the manhole is on the sidewalk, the steps S1 and S2 may cause obstacles to pedestrians and bicycles. Therefore, it is necessary to periodically investigate the wear of the lid contact surface 13, the lid bearing surface 23, and the road surface 920, and conventionally, the measurement is performed manually using a caliper.

  FIG. 5 is a diagram in which lines and symbols indicating dimensions are added to a digital image of a manhole for explanation. For example, if a manhole on the roadway is photographed from the sidewalk, a digital image of the manhole as shown in FIG. 5 can be acquired. A digital image is an image expressed by a set of dots (pixels). FIG. 6 is a diagram illustrating a situation when the manhole 1 is photographed by the camera 700. Since the camera 700 is at the height of a human eye, when shooting the manhole 1, the camera 700 is directed slightly downward. A line 31 indicates the direction of the camera, and a line 32 is a line parallel to the road surface. θ is an angle formed by the line 31 and the line 32 and is called a depression angle. On the digital image 800, the outer periphery of the frame surface is an ellipse having a major axis d1 and a short shape f1, the inner periphery of the frame surface is an ellipse having a major axis d2 and a minor axis f2, and the outer periphery of the lid is an ellipse having a major axis d3 and a minor axis f3. s1 is a step between the lid surface 12 and the frame surface 22 on the digital image 800, and s2 is a step between the road surface 920 and the frame surface 22 on the digital image 800. Although the direction of d1 in FIG. 6 is different from that in FIG. 5, since the manhole is circular, it has the same length in any direction. D1, d2, d3, f1, f2, f3, s1, and s2 are values corresponding to the number of dots on the digital image. The “value corresponding to the number of dots” may be the number of dots of the first image taken, may be a value corrected by enlargement / reduction of a digital image, or may be a length on the printed paper. However, another unit value corresponding to the number of dots may be used.

And the actual diameter and depression angle θ and the major axis and minor axis on the digital image,
D1 = k · d1, D2 = k · d2, D3 = k · d3 (1)
sin θ = f1 / d1 = f2 / d2 = f3 / d3 (2)
However, k is a coefficient relationship indicating the relationship between the value corresponding to the number of dots and the actual length.

FIG. 7 is an enlarged view of the manhole 1 portion of FIG. Similarly, the actual step S1 and the step s1 on the digital image 800 include
cos θ = s1 / (S1 / k) (3)
Thus, the actual step S2 and the step s2 on the digital image 800 are
cos θ = s2 / (S2 / k) (4)
The relationship holds. In the present invention, both or one of the step S1 and the step S2 is obtained using the relationships of the expressions (1) to (4).

<Step measurement method>
FIG. 8 is a diagram showing a flow of the step measuring method of the present invention. The step measuring method for measuring a step of a manhole according to the present invention includes a digital image acquisition step (S110), a depression angle calculation step (S120), a unit length calculation step (S130), and a step calculation step (S140). In the digital image acquisition step (S110), a digital image of a manhole expressed by a set of dots is acquired. That is, a digital image such as the digital image 800 in FIG. 5 is acquired. Here, “acquisition” includes taking a picture and printing out by a person, or taking a data into a computer or the like by taking a picture.

In the depression angle calculating step (S120), a value corresponding to the number of long diameter dots in the digital image and a value corresponding to the number of short diameter dots for the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid Ask for. Specifically, any one of d1, f1, d2, f2, d3, and f3 in FIG. 5 is obtained, and a value corresponding to the major axis obtained from the digital image is d, and a value corresponding to the minor axis is f. . Then, a value corresponding to the depression angle θ when the manhole in the digital image is photographed is calculated. For example,
sin θ = f / d (5)
And sin θ may be a value corresponding to the depression angle θ,
θ = sin ⁻¹ f / d (6)
The depression angle θ itself may be a value corresponding to the depression angle θ, or simply f / d may be a value corresponding to the depression angle θ. Note that it is not necessary to limit to these, and any value corresponding to the depression angle θ on a one-to-one basis may be used. Also, from equation (2)
sin θ = f1 / d1 = f2 / d2 = f3 / d3
Therefore, any of the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid may be used. The subject of step S120 may be a person, or a person may input a numerical value into a spreadsheet software or the like and cause the computer to calculate.

In the unit length calculation step (S130), the relationship between the value corresponding to the number of dots and the actual length is obtained from the value d corresponding to the number of long-diameter dots and the actual manhole dimension (D1, D2, or D3). calculate. For example, when the value d corresponding to the number of long-diameter dots is d1, D1 is the actual manhole dimension D,
k = D / d (7)
Thus, a coefficient k indicating the relationship between the value corresponding to the number of dots and the actual length is obtained. The subject of step S130 may be a person, or a person may input a numerical value into spreadsheet software or the like and cause the computer to calculate. From equation (1),
k = D1 / d1 = D2 / d2 = D3 / d3 (8)
Therefore, any of the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid may be used.

In the step calculation step (S140), a value (s1 or s2) corresponding to the number of bits in the minor axis direction in the digital screen of the inner surface or outer surface of the manhole frame is obtained, and a value corresponding to the depression angle θ (for example, sin θ And the relationship between the value corresponding to the number of dots and the actual length (coefficient k) is used to calculate the actual length. Specifically, when obtaining the step S1, S1 = k · s1 / cos θ (9)
When obtaining the step S2, S2 = k · s2 / cos θ (10)
Seek like. The subject of step S140 may be a person, or a person may input a numerical value into spreadsheet software or the like and cause the computer to calculate.

  According to the level difference measuring method of the present invention, if a digital image of a manhole is photographed on or near a road, the level difference can be measured using the acquired digital image. Therefore, the step of the manhole can be measured safely at low cost. In particular, when there is a manhole on the roadway, since a digital image of the manhole on the roadway can be taken even from the sidewalk, there is no need for people to enter the roadway and it is safe.

<Step measurement support device>
FIG. 9 shows a functional configuration example of the level difference measurement support apparatus of the present invention, and FIG. 10 shows a throw of the level difference measurement method when the level difference measurement support apparatus is used. The level difference measurement support apparatus 100 includes an image display unit 170, an operation unit 180, and a recording unit 190 that records information on manhole dimensions, and supports the implementation of the level difference measurement method. The image display means 170 is a display or the like, and the operation means 180 is a mouse, a touch pen, a touch panel, a keyboard, or the like. The level difference measurement support apparatus 100 further includes a digital image acquisition unit 110, a depression angle calculation unit 120, a unit length calculation unit 130, and a level difference calculation unit 140.

  Next, processing using each component will be described with reference to the drawings. 11 is a diagram for explaining step S121, FIG. 12 is a diagram for explaining step S122, FIG. 13 is a diagram for explaining step S141, and FIG. 14 is a diagram for explaining step S142. The digital image acquisition unit 110 acquires a digital image of a manhole represented by a set of dots (S110). “Acquisition” here means acquiring electronic data of a digital image.

  The depression angle calculation unit 120 displays a digital image of a manhole and a rectangular cursor on the image display unit 170 (S121). An example of the digital image displayed on the image display means 170 at this time is shown in FIG. In addition to the manhole image, a rectangular cursor 300 is also displayed on the digital image 800. Then, the operator adjusts the position and size of the cursor using the operation means 180 so that the rectangle is in contact with the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid (S122). FIG. 12 shows the state after the adjustment. This figure is an example in which the size of the cursor position is adjusted so as to contact the outer periphery of the frame surface. Normally, it seems that the outer periphery of the frame surface is most easily understood. However, as described in the step measurement method, the position and size of the cursor may be adjusted so that the rectangle is in contact with the inner periphery of the frame surface or the outer periphery of the lid. If the camera is tilted at the time of shooting, the major axis and minor axis directions are not horizontal and vertical but diagonal. In such a case, the digital image of the manhole may be adjusted in step S121 so that the major axis is horizontal, or in step S122, the cursor is tilted so that the major axis direction coincides with the long side of the rectangle. May be added.

  The depression angle calculation unit 120 calculates a value corresponding to the number of dots on the long side of the rectangle and a value corresponding to the number of dots on the short side as digital values for the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid. A value d corresponding to the number of dots of the long diameter in the image and a value f corresponding to the number of dots of the short diameter are set (S123). In the example of FIG. 12, d1 is d and f1 is f. The depression angle calculation unit 120 calculates a value corresponding to the depression angle θ when the manhole in the digital image is photographed, from the value d corresponding to the obtained number of long diameter dots and the value f corresponding to the number of short diameter dots ( S124). Specifically, the calculation may be performed as shown in Equation (5) or Equation (6).

  The unit length calculation unit 130 calculates the relationship between the value corresponding to the number of dots and the actual length from the value d corresponding to the number of long-diameter dots and the manhole size information recorded in the recording unit 190 (S130). ). Specifically, the coefficient k indicating the relationship between the value corresponding to the number of dots and the actual length is obtained by Expression (7). When a plurality of diameter values are recorded in the recording unit 190, the unit length calculation unit 130 selects which value to use. The selection may be made by the operator, or may be selected on the basis of the equipment record by providing a function for confirming the equipment record, and information on the manhole type is added to the digital image of the manhole, You may select based on the additional information.

The step calculation unit 140 displays the digital image of the manhole and a pointer for indicating two positions on the image display means (S141). An example of the digital image displayed on the image display means 170 at this time is shown in FIG. In addition to the manhole image, the digital image 800 also displays pointers 400-1 and 400-2 for specifying two positions. Then, the level difference calculation unit 140 causes the operator to use the operation unit 180 to place the pointers 400-1 and 4002 at both ends of the inner side surface or the outer side surface of the manhole frame in the minor axis direction (S142). ). FIG. 14 is a diagram illustrating a state after the position of the pointer is adjusted. The level difference calculating unit 140 obtains a value s corresponding to the number of bits in the interval between two pointers. In the example of FIG. 14, s is s1. The level difference calculating unit 140 calculates and outputs the actual length of the inner side surface or the outer side surface using the value corresponding to the depression angle θ and the relationship (specifically, the coefficient k). In particular,
S = k · s / cos θ (11)
It is sufficient to calculate as follows. If there is a standard for the level difference, the result compared with the standard may be output.

  According to the level difference measurement support apparatus of the present invention, a person can easily execute the level difference measurement method of the present invention. Therefore, the step of the manhole can be measured safely and easily.

[Program, recording medium]
The various processes described above are not only executed in time series according to the description, but may also be executed in parallel or individually as required by the processing capability of the apparatus that executes the processes. Needless to say, other modifications are possible without departing from the spirit of the present invention.

  Further, when the above-described configuration is realized by a computer, processing contents of functions that each device should have are described by a program. The processing functions are realized on the computer by executing the program on the computer.

  The program describing the processing contents can be recorded on a computer-readable recording medium. As the computer-readable recording medium, for example, any recording medium such as a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory may be used.

  The program is distributed by selling, transferring, or lending a portable recording medium such as a DVD or CD-ROM in which the program is recorded. Furthermore, the program may be distributed by storing the program in a storage device of the server computer and transferring the program from the server computer to another computer via a network.

  A computer that executes such a program first stores, for example, a program recorded on a portable recording medium or a program transferred from a server computer in its own storage device. When executing the process, the computer reads a program stored in its own recording medium and executes a process according to the read program. As another execution form of the program, the computer may directly read the program from a portable recording medium and execute processing according to the program, and the program is transferred from the server computer to the computer. Each time, the processing according to the received program may be executed sequentially. Also, the program is not transferred from the server computer to the computer, and the above-described processing is executed by a so-called ASP (Application Service Provider) type service that realizes the processing function only by the execution instruction and result acquisition. It is good. Note that the program in this embodiment includes information that is used for processing by an electronic computer and that conforms to the program (data that is not a direct command to the computer but has a property that defines the processing of the computer).

  In this embodiment, the present apparatus is configured by executing a predetermined program on a computer. However, at least a part of these processing contents may be realized by hardware.

DESCRIPTION OF SYMBOLS 1 Manhole 10 Lid 11 Lid body 12 Lid surface 13 Lid contact surface 14 Rubber packing 20 Frame 21 Frame main body 22 Frame surface 23 Lid bearing surface 24 Rubber packing bearing surface 31, 32 Line 100 Step measurement support device 110 Digital image acquisition part 120 Calculation unit 130 Unit length calculation unit 140 Step calculation unit 170 Image display unit 180 Operation unit 190 Recording unit 251 Inner side 252 Outer side 300 Cursor 400 Pointer 700 Camera 800 Digital image 900 Road 920 Road surface

Claims (6)

A step measurement method for measuring a manhole step,
A digital image acquisition step of acquiring a digital image of a manhole represented by a set of dots;
Obtaining a value corresponding to the number of long diameter dots and a value corresponding to the number of short diameter dots in the digital image for the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid, A depression angle calculating step for calculating a value corresponding to the depression angle when photographing the manhole in the middle,
A unit length calculation step for calculating the relationship between the value corresponding to the number of dots and the actual length from the value corresponding to the number of dots of the major axis and the actual manhole dimension;
A value corresponding to the number of bits in the minor axis direction in the digital screen on the inner side surface or outer side surface of the manhole frame is obtained, and the actual step length is calculated using the value corresponding to the depression angle and the relationship. A step calculation step to calculate,
A level difference measuring method. It is a level | step difference measuring method of Claim 1, Comprising:
The value corresponding to the number of dots of the major axis is d, the value corresponding to the number of dots of the minor axis is f, the depression angle is θ, the size of the actual manhole part corresponding to the d is D, and the inside of the manhole frame A value corresponding to the number of bits in the minor axis direction in the digital screen on the side surface or the outer surface is s, and the actual step length is S,
The value corresponding to the depression angle is a value using f / d,
The relationship is a coefficient k obtained as k = D / d,
The actual step length S is S = k · s / cos θ. A step measurement support device having image display means, operation means, and recording means for recording manhole dimension information, and supporting measurement of a manhole step,
A digital image acquisition unit for acquiring a digital image of a manhole represented by a set of dots;
(a1) Displaying the manhole digital image and a rectangular cursor on the image display means,
(a2) The operator is allowed to adjust the position and size of the cursor so that the rectangle is in contact with the outer periphery of the manhole frame surface, the inner periphery of the frame surface, or the outer periphery of the lid using the operation means,
(a3) A value corresponding to the number of dots on the long side of the rectangle and a value corresponding to the number of dots on the short side are the digital values for the outer periphery of the frame surface of the manhole, the inner periphery of the frame surface, or the outer periphery of the lid. A value corresponding to the number of dots of the long diameter in the image and a value corresponding to the number of dots of the short diameter,
(a4) from a value corresponding to the obtained number of dots of the long diameter and a value corresponding to the number of dots of the short diameter, a depression angle calculation unit that calculates a value corresponding to the depression angle when the manhole in the digital image is photographed,
From the value corresponding to the number of dots of the major axis and the information of the size of the manhole recorded in the recording means, a unit length calculation unit for calculating the relationship between the value corresponding to the number of dots and the actual length,
(b1) A digital image of the manhole and a pointer for indicating two positions are displayed on the image display means,
(b2) The operator uses the operation means to place the pointers at both ends in the minor axis direction of the inner surface or the outer surface of the manhole frame in the digital screen,
(b3) Obtain a value corresponding to the number of bits in the interval between the two pointers,
(b4) using the value corresponding to the depression angle and the relationship, a step calculation unit that calculates the actual step length of the inner surface or the outer surface;
A level difference measurement support device. It is a level | step difference measurement assistance apparatus of Claim 3, Comprising:
The value corresponding to the number of dots of the long diameter is d, the value corresponding to the number of dots of the short diameter is f, the depression angle is θ, the size of the actual manhole portion corresponding to the d is D, and the interval between the two pointers S is a value corresponding to the number of bits of S, and S is the length of the actual step ,
The value corresponding to the depression angle is a value using f / d,
The relationship is a coefficient k obtained as k = D / d,
The actual step length S is S = k · s / cos θ.   A step measurement support program for operating a computer as the step measurement support device according to claim 3 or 4.   The recording medium which recorded the level | step difference measurement assistance program of Claim 5.

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