CN110793495A - Method and device for measuring shortest distance between front view and front view of vehicle - Google Patents

Method and device for measuring shortest distance between front view and front view of vehicle Download PDF

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Publication number
CN110793495A
CN110793495A CN201911249613.8A CN201911249613A CN110793495A CN 110793495 A CN110793495 A CN 110793495A CN 201911249613 A CN201911249613 A CN 201911249613A CN 110793495 A CN110793495 A CN 110793495A
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point
wide
objective lens
camera
angle objective
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金正�
王飞
张磊
徐武松
谢佳玫
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WUXI XINGDI INSTRUMENT CO Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C3/00—Measuring distances in line of sight; Optical rangefinders
    • G01C3/32—Measuring distances in line of sight; Optical rangefinders by focusing the object, e.g. on a ground glass screen
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness

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  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Measurement Of Optical Distance (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The invention provides a device for measuring the shortest distance between the front view field and the vehicle, comprising: the device comprises a calibration rod, a wide-angle objective lens, a camera and an upper computer; the calibration rod is vertically arranged on the ground; a calibration datum point A and a correction auxiliary point B are arranged on the calibration rod; the height of the calibration reference point A is equal to the vertical height H from the eye point position of the driver to the ground projection point; the correction auxiliary point B is positioned right below the calibration reference point A, and the distance between the calibration reference point A and the correction auxiliary point B is h; the wide-angle objective lens and the camera are arranged along a horizontal light path, and the wide-angle objective lens is arranged on the front side of the camera; the calibration reference point A is positioned in the center of the wide-angle objective and the horizontal light path where the center of an imaging element of the camera is positioned; the camera is connected with an upper computer; the distance between the calibration reference point A and the center of the wide-angle objective lens 4 is L; the distance between the center of the wide-angle objective lens and the center of the imaging element of the camera is one focal length f' of the wide-angle objective lens. The invention has simple operation, accurate measurement and strong practicability.

Description

Method and device for measuring shortest distance between front view and front view of vehicle
Technical Field
The invention relates to the field of photogrammetry, in particular to a method and a device for measuring the shortest distance between a front view field and a vehicle.
Background
The minimum distance is the measured distance between the projected point of the driver's eyepoint location on the ground to the closest point where the driver just sees the ground. The minimum distance is one of the measurement items required by national military standard GJB 59.33-91 'armored vehicle test regulation inspection range', the national military standard is mandatory, and the minimum distance also relates to whether a driver can timely and accurately find and avoid the obstacle on the front road. The measurement of the nearest distance has important significance on the driving safety and the maneuverability of the vehicle.
The traditional measuring device is a view lamp holder, and the using method comprises the steps of placing the view lamp holder at the position of a driver in a moonless environment at night, turning on a view lamp, observing the illumination condition of the view lamp, and measuring the distance from the nearest point of the ground illuminated by the view lamp to the projection point of the position of the driver on the ground, namely the nearest distance. The measurement process using the device is simple, but the device needs to be measured in a dark environment and is greatly influenced by environmental factors. The nearest point of illumination needs to be observed manually, and the influence of human factors is large. Measurement errors exist during measurement, so that the overall measurement result error is large.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method and a device for measuring the shortest distance between the front view of a vehicle, which have the characteristics of simple operation, accurate measurement and strong practicability.
The embodiment of the invention provides a device for measuring the shortest distance between a front view field and a vehicle, which comprises: the device comprises a calibration rod, a wide-angle objective lens, a camera and an upper computer;
the calibration rod is vertically arranged on the ground; a calibration datum point A and a correction auxiliary point B are arranged on the calibration rod; the height of the calibration reference point A is equal to the vertical height H from the eye point position of the driver to the ground projection point; the correction auxiliary point B is positioned right below the calibration reference point A, and the distance between the calibration reference point A and the correction auxiliary point B is h;
the wide-angle objective lens and the camera are arranged along a horizontal light path, and the wide-angle objective lens is arranged on the front side of the camera; the calibration reference point A is positioned in the center of the wide-angle objective and the horizontal light path where the center of an imaging element of the camera is positioned; the camera is connected with an upper computer;
the distance between the calibration reference point A and the center of the wide-angle objective lens 4 is L;
the distance between the center of the wide-angle objective lens and the center of the imaging element of the camera is one focal length f' of the wide-angle objective lens.
Preferably, the calibration rod is made of a material capable of being attracted by a magnet, and scales are arranged on the calibration rod; the calibration reference point A and the correction auxiliary point B adopt magnetic mark points with different colors and are adsorbed on the calibration rod.
The embodiment of the invention also provides a method for measuring the shortest distance between the front view and the field of view of the vehicle, which comprises the following steps:
s1, a calibration rod, a wide-angle objective lens and a camera are installed, and the camera and an upper computer are connected;
vertically installing the calibration rod on the ground; the wide-angle objective lens and the camera are arranged along a horizontal light path, the wide-angle objective lens is positioned on the front side of the camera, and the distance between the center of the wide-angle objective lens and the center of an imaging element of the camera is one-time focal length f' of the wide-angle objective lens;
finding a scale corresponding to the vertical height H from the eyepoint position of the driver to the ground projection point on the calibration rod, aligning the center of the wide-angle objective lens with the camera to the scale, observing an imaged image through an upper computer, and simultaneously adjusting the wide-angle objective lens and the camera until the scale is imaged at the center of the image; setting a calibration reference point A on the scale, and setting a correction auxiliary point B at a distance h below the calibration reference point A; the distance between the calibration reference point A and the center of the wide-angle objective is L;
s2, setting the theoretical image height after the correction auxiliary point B is imaged as d since the focal length f' of the wide-angle objective lens is known1From the triangle similarity theorem, it can be known that:
Figure BDA0002308648840000021
obtaining a theoretical image height:
Figure BDA0002308648840000022
the imaging position of the correction auxiliary point B is observed through the upper computer 6, and the actual imaging height is d2And obtaining the following according to a first-order radial distortion correction formula:
d1＝d2(1+k1rd 2)
wherein r isd 2＝d2 2Simultaneously obtained distortion parameter k1Comprises the following steps:
Figure BDA0002308648840000023
s3, a ground closest point which can be observed by the camera through the wide-angle objective lens is a view closest point C, and the view closest point C is located on a plane determined by the three points of the calibration reference point A, the correction auxiliary point B and the center of the wide-angle objective lens;
the image height of C imaging of the observation view closest distance point on the upper computer is s1Obtaining the corrected image height s according to a first-order radial distortion correction formula2Namely:
Figure BDA0002308648840000024
the minimum distance of the vehicle front view is X, and can be obtained by a triangle similarity principle:
Figure BDA0002308648840000025
the minimum distance X of the vehicle front view is as follows:
Figure BDA0002308648840000026
further, the first order radial distortion correction formula is:
xc＝xd(1+k1rd 2)
yc＝yd(1+k1rd 2)
wherein x isd，ydAs actual image coordinates of the image point, xc，ycIs the distortion corrected coordinate of the image point, k1Is an order radial distortion parameter, rdIs a distortion radius, and
Figure BDA0002308648840000027
preferably, the calibration rod is made of a material capable of being attracted by a magnet, and scales are arranged on the calibration rod; the calibration reference point A and the correction auxiliary point B adopt magnetic mark points with different colors and are adsorbed on the calibration rod.
The invention has the advantages that:
1) the method provided by the invention corrects the first-order radial distortion of the wide-angle objective lens and improves the measurement precision.
2) The invention has the following measurement points: the point A, the point B and the point C are positioned on the same two-dimensional plane of the three-dimensional world, the distance can be directly calculated, the space three-dimensional coordinates of the points do not need to be solved, and the calculation process is simplified.
3) The method can realize the closest distance of automatic measurement and has strong practicability.
4) The camera imaging measurement is less influenced by human and environmental factors.
Drawings
Fig. 1 is a schematic diagram of a minimum distance X of a vehicle front view according to an embodiment of the present invention.
Fig. 2 is a schematic view of a measuring apparatus according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of first-order radial distortion correction for a wide-angle objective lens according to an embodiment of the present invention.
Fig. 4 is a schematic view illustrating the measurement of the minimum distance X in the front view of the vehicle according to the embodiment of the invention.
Detailed Description
The invention is further illustrated by the following specific figures and examples.
The embodiment of the invention provides a device for measuring the shortest distance between a front view and a field of view of a vehicle.
The shortest distance of the vehicle front view is shown in fig. 1, and a distance X from a projection point of a driver eye point position on the ground to the closest point where the driver can just see the ground in fig. 1 is the shortest distance of the vehicle front view;
in the embodiment, the device for measuring the minimum distance between the front view field of the vehicle comprises a calibration rod 3, a wide-angle objective lens 4, a camera 5 and an upper computer 6;
the calibration rod 3 is vertically arranged on the ground 1; a calibration datum point A and a correction auxiliary point B are arranged on the calibration rod 3; the height of the calibration reference point A is equal to the vertical height H from the eye point position of the driver to the ground projection point; the correction auxiliary point B is positioned right below the calibration reference point A, and the distance between the calibration reference point A and the correction auxiliary point B is h;
as a preferable scheme, the calibration rod 3 is made of a material capable of being attracted by a magnet, such as an iron rod, and is provided with scales; the calibration reference point A and the correction auxiliary point B can adopt magnetic marking points 2 with different colors and are adsorbed on a calibration rod 3; when the shortest distance of the vehicle front view is measured for different vehicles, the calibration datum point A can correspondingly adjust the height H;
in other embodiments, the calibration reference point a and the correction auxiliary point B may be directly marked on the calibration rod 3 by using a color pen; the calibration rod 3 can be provided with no scales, and a tape can be used for determining the height H and the distance H;
the wide-angle objective lens 4 and the camera 5 are arranged along a horizontal optical path, and the wide-angle objective lens 4 is arranged on the front side of the camera 5; the calibration reference point A is positioned on a horizontal light path where the center of the wide-angle objective 4 and the center of an imaging element of the camera 5 are positioned; the camera 5 is connected with an upper computer 6;
the distance between the calibration reference point A and the center of the wide-angle objective lens 4 is L;
the distance between the center of the wide-angle objective lens 4 and the center of an imaging element of the camera 5 is one focal length f' of the wide-angle objective lens 4;
the wide-angle objective 4 is adopted in the measuring device, distortion is inevitably generated, the readability of the image is influenced by the distortion, and the measuring precision is further reduced; optical distortions are mainly classified into three categories: radial distortion, eccentric distortion, and thin prism distortion; according to the optical imaging principle of the lens, the distortion model is as follows:
Dx(x,y)＝k1x(x2+y2)+(p1(3x2+y2)+2p2xy)+s1(x2+y2)
Dy(x,y)＝k2x(x2+y2)+(p2(3x2+y2)+2p1xy)+s2(x2+y2)
wherein D isx，DyIs a nonlinear distortion value, Dx，DyThe first term of (a) is called radial distortion, the second term is called eccentric distortion, and the third term is called thin prism distortion, where k is1，k2，p1，p2，s1，s2Referred to as nonlinear distortion parameters;
considering that in the present embodiment, the radial distortion has the greatest influence on the image; therefore, the first-order radial distortion correction formula is measured and calculated to correct the first-order radial distortion of the image, so that the measurement precision is improved; the first order radial distortion correction formula can be written as:
xc＝xd(1+k1rd 2)
yc＝yd(1+k1rd 2)
wherein x isd，ydAs actual image coordinates of the image point, xc，ycIs the distortion corrected coordinate of the image point, k1Is an order radial distortion parameter, rdIs a distortion radius, and
Figure BDA0002308648840000041
the method for measuring the minimum distance between the front view of the vehicle provided by the embodiment comprises the following steps:
s1, installing the calibration rod 3, the wide-angle objective 4 and the camera 5, and connecting the camera 5 with the upper computer 6;
the calibration rod 3 is made of a material capable of being attracted by a magnet, such as an iron rod, and scales are arranged on the calibration rod; vertically installing a calibration rod 3 on the ground 1; the wide-angle objective lens 4 and the camera 5 are arranged along a horizontal light path, the wide-angle objective lens 4 is positioned at the front side of the camera 5, and the distance between the center of the wide-angle objective lens 4 and the center of an imaging element of the camera 5 is one-time focal length f' of the wide-angle objective lens 4;
finding a scale corresponding to the vertical height H from the eyepoint position of the driver to the ground projection point on the calibration rod 3, aligning the center of the wide-angle objective lens 4 with the camera 5 to the scale, observing an imaged image through the upper computer 6, and simultaneously adjusting the wide-angle objective lens 4 and the camera 5 until the scale is imaged at the center of the image; a calibration datum point A is arranged on the scale, and a correction auxiliary point B is arranged at a distance h below the calibration datum point A, for example, the calibration datum point A and the correction auxiliary point B can adopt magnetic mark points 2 with different colors and are adsorbed on a calibration rod 3; the distance between the calibration reference point A and the center of the wide-angle objective lens 4 is L;
s2, setting the theoretical image height after the correction auxiliary point B is imaged as d since the focal length f' of the wide-angle objective lens is known1From the triangle similarity theorem, it can be known that:
Figure BDA0002308648840000042
obtaining a theoretical image height:
Figure BDA0002308648840000043
the imaging position of the correction auxiliary point B is observed through the upper computer 6, and the actual imaging height is d2And obtaining the following according to a first-order radial distortion correction formula:
d1＝d2(1+k1rd 2)
wherein r isd 2＝d2 2Simultaneously obtained distortion parameter k1Comprises the following steps:
Figure BDA0002308648840000044
s3, a ground closest point which can be observed by the camera 5 through the wide-angle objective 4 is a view closest point C, and the view closest point C is located on a plane determined by the calibration reference point A, the correction auxiliary point B and the center of the wide-angle objective 4;
the image height of C imaging of the observation view closest distance point on the upper computer 6 is s1Obtaining the corrected image height s according to a first-order radial distortion correction formula2Namely:
Figure BDA0002308648840000051
the minimum distance of the vehicle front view is X, and can be obtained by a triangle similarity principle:
Figure BDA0002308648840000052
the minimum distance X of the vehicle front view is as follows:
Figure BDA0002308648840000053
finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims (5)

1. A vehicle forward field of view closest distance measuring device, comprising: the device comprises a calibration rod (3), a wide-angle objective (4), a camera (5) and an upper computer (6);
the calibration rod (3) is vertically arranged on the ground (1); a calibration datum point A and a correction auxiliary point B are arranged on the calibration rod (3); the height of the calibration reference point A is equal to the vertical height H from the eye point position of the driver to the ground projection point; the correction auxiliary point B is positioned right below the calibration reference point A, and the distance between the calibration reference point A and the correction auxiliary point B is h;
the wide-angle objective lens (4) and the camera (5) are arranged along a horizontal light path, and the wide-angle objective lens (4) is arranged on the front side of the camera (5); the calibration reference point A is positioned on a horizontal light path where the center of the wide-angle objective lens (4) and the center of an imaging element of the camera (5) are positioned; the camera (5) is connected with an upper computer (6);
the distance between the calibration reference point A and the center of the wide-angle objective lens (4) is L;
the distance between the center of the wide-angle objective lens (4) and the center of an imaging element of the camera (5) is one focal length f' of the wide-angle objective lens (4).
2. The vehicle forward FOV closest distance measuring device of claim 1,
the calibration rod (3) is made of a material capable of being attracted by a magnet, and scales are arranged on the calibration rod; the calibration reference point A and the correction auxiliary point B adopt magnetic mark points (2) with different colors and are adsorbed on a calibration rod (3).
3. A method for measuring the shortest distance between the field of vision in front of a vehicle is characterized by comprising the following steps:
s1, a calibration rod (3), a wide-angle objective lens (4) and a camera (5) are installed, and the camera (5) and an upper computer (6) are connected;
vertically installing a calibration rod (3) on the ground (1); the wide-angle objective lens (4) and the camera (5) are arranged along a horizontal light path, the wide-angle objective lens (4) is positioned on the front side of the camera (5), and the distance between the center of the wide-angle objective lens (4) and the center of an imaging element of the camera (5) is one-time focal length f' of the wide-angle objective lens (4);
finding a scale corresponding to the vertical height H from the eyepoint position of the driver to the ground projection point on the calibration rod (3), aligning the center of the wide-angle objective (4) with the camera (5) to the scale, observing an imaging image through the upper computer (6), and adjusting the wide-angle objective (4) and the camera (5) until the scale is imaged at the center of the image; setting a calibration reference point A on the scale, and setting a correction auxiliary point B at a distance h below the calibration reference point A; the distance between the calibration reference point A and the center of the wide-angle objective lens (4) is L;
s2, setting the theoretical image height after the correction auxiliary point B is imaged as d since the focal length f' of the wide-angle objective lens is known1From the triangle similarity theorem, it can be known that:
obtaining a theoretical image height:
Figure FDA0002308648830000012
the imaging position of the correction auxiliary point B is observed through an upper computer (6), and the actual imaging height is d2And obtaining the following according to a first-order radial distortion correction formula:
d1＝d2(1+k1rd 2)
wherein r isd 2＝d2 2Simultaneously obtained distortion parameter k1Comprises the following steps:
Figure FDA0002308648830000021
s3, a ground closest point which can be observed by the camera (5) through the wide-angle objective lens (4) is a view closest point C, and the view closest point C is located on a plane determined by the three points of the calibration reference point A, the correction auxiliary point B and the center of the wide-angle objective lens (4);
the image height of C imaging of the observation view closest distance point on the upper computer (6) is s1Obtaining the corrected image height s according to a first-order radial distortion correction formula2Namely:
Figure FDA0002308648830000022
the minimum distance of the vehicle front view is X, and can be obtained by a triangle similarity principle:
Figure FDA0002308648830000023
the minimum distance X of the vehicle front view is as follows:
Figure FDA0002308648830000024
4. the method of measuring the FOV of claim 3,
the first order radial distortion correction formula is:
xc＝xd(1+k1rd 2)
yc＝yd(1+k1rd 2)
wherein x isd，ydAs actual image coordinates of the image point, xc，ycIs the distortion corrected coordinate of the image point, k1Is an order radial distortion parameter, rdIs a distortion radius, and
Figure FDA0002308648830000025
5. the method of measuring the FOV of claim 3,
the calibration rod (3) is made of a material capable of being attracted by a magnet, and scales are arranged on the calibration rod; the calibration reference point A and the correction auxiliary point B adopt magnetic mark points (2) with different colors and are adsorbed on a calibration rod (3).
CN201911249613.8A 2019-12-09 2019-12-09 Method and device for measuring shortest distance between front view and front view of vehicle Pending CN110793495A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113566717A (en) * 2021-09-27 2021-10-29 陕西汽车集团股份有限公司 Method and device for detecting bending height of double-bent longitudinal beam

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113566717A (en) * 2021-09-27 2021-10-29 陕西汽车集团股份有限公司 Method and device for detecting bending height of double-bent longitudinal beam
CN113566717B (en) * 2021-09-27 2021-12-10 陕西汽车集团股份有限公司 Method and device for detecting bending height of double-bent longitudinal beam

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