CN109443476B - Non-contact measuring device and method for water level fluctuation process - Google Patents
Non-contact measuring device and method for water level fluctuation process Download PDFInfo
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- CN109443476B CN109443476B CN201811206706.8A CN201811206706A CN109443476B CN 109443476 B CN109443476 B CN 109443476B CN 201811206706 A CN201811206706 A CN 201811206706A CN 109443476 B CN109443476 B CN 109443476B
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- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
Abstract
The invention discloses a non-contact measuring device and a non-contact measuring method for a water level fluctuation process, which comprise the steps of setting and measuring actual position coordinates of a calibration point and an inspection point; laterally shooting a reference plane to obtain video data; decomposing the video data into images, and correcting the images to an orthographic projection plane of a reference plane; identifying an internal standard fixed point and a check point of the image, and matching the pixel coordinate of the fixed point with the actual position coordinate to obtain a calibration coefficient; calculating the coordinate of the actual position of the check point according to the calibration coefficient and the pixel coordinate of the check point, calculating and comparing the deviation between the calculated value of the actual position of the check point and the measured value, and executing the next step when the deviation value of the calculated value and the measured value is smaller than the preset deviation value; and acquiring the actual elevation value of the characteristic point of the measured water surface according to the pixel coordinate of the characteristic point of the measured water surface. The invention belongs to a non-contact method, which has no disturbance to a measuring object; the instrument is simple to erect, portable to operate and low in cost; lateral observation, which is suitable for complex environment; the automation degree is high, and the potential safety hazard of temporary observation personnel does not exist.
Description
Technical Field
The invention belongs to the technical field of hydraulic observation, and particularly relates to a non-contact measuring device and method for a water level fluctuation process, which are particularly suitable for field water level observation of a water outlet structure with difficult instrument erection conditions or short-time measurement.
Background
In the design, operation and management of hydraulic engineering, no matter long-term or temporary observation, real-time water level data of a river channel or a wading building are the most important and basic information of daily management and scientific research. For example, for observing the river water level in a drainage basin, a hydrological station is usually set to collect information such as water level and flow rate; for the water levels of wading buildings (such as reservoirs, dams, spillways, flood discharge tunnels, navigation channels, diversion channels, flat kill wells, tail water of power stations, plunge ponds, breakwaters and the like) and upstream and downstream riverways, some characteristic water levels in the design stage are key parameters for determining the height of the buildings, and water level data and fluctuation processes thereof are important parameters for checking engineering design and evaluating engineering safety in the initial operation and debugging stages of the buildings. Therefore, the acquisition of the high-precision water level and the water surface fluctuation process plays an important role in the safe operation and management of the hydraulic and hydroelectric engineering hub and the river channel.
In laboratories and actual engineering sites, real-time observation of water level data and water surface fluctuation process is often required. In a laboratory, methods for measuring the water level generally include a water level stylus method, a direct reading method, a wire measuring method, a wave height meter method, a radar water level meter method, an ultrasonic water level meter method, and the like; in the field engineering field, the water level data acquisition method mainly comprises a water gauge method, a float type water level meter method, a pressure water level meter method, a radar water level meter method, an ultrasonic water level meter method and the like. The basic principle of these methods is to vertically set up a scale or a sensor, and the instrument needs to be set up right above the measurement point, and these methods all have some limitations, such as: measuring a needle, a measuring rope or a water gauge: the method is a contact type measuring method, needs manual reading, has low automation degree, is difficult to continuously measure the water surface, and is easy to damage a water gauge under the impact of high-speed water flow when the water flow rate is high; a float type water level meter: the method needs to be provided with well logging, is suitable for measuring the water level of the low-sand water body, needs to regularly correct the water level and clear siltation in the pipeline, and has higher operation cost; thirdly, the pressure water level meter: the underwater work is realized, the precision is influenced by water body impurities and waves, the instrument correction is complex, and the failure rate is high; fourthly, the ultrasonic water level meter and the radar water level meter: by adopting the acoustic reflection principle, the measuring instrument is preassembled and calibrated, auxiliary facilities are required to be matched, and the use cost is high. In practical application, some instruments need to carry out real-time monitoring and feedback on a long sequence of a water level process, a water level measuring instrument is relatively fixed, the sampling frequency is relatively low, the installation and use frequency of the instrument is high, the period is long, and the average cost is low; some instruments are short-term temporary observation, the instruments are temporarily used and erected, sampling frequencies are different according to requirements, the requirements of the instruments are often high, but the service cycle is short, and the observation cost is relatively high. For some overflowing buildings (such as spillways, ship lock navigation channels and the like), the on-way water level and water surface fluctuation process of the spillways needs to be observed and feedback analyzed, a plurality of water level observation instruments need to be temporarily arranged on the spillways and the upstream and downstream of the spillways, and at the moment, the instruments are difficult to arrange and install, and because the requirements are not required during design, the prototype observation difficulty is very high, the danger coefficient is high, and the instrument installation cost is high. Moreover, these instruments and devices often need to be removed and installed at any time during a short period of use, which puts higher demands on the water level observation instrument and also greatly increases the investment cost. At present, with the increasing demands and requirements for water level observation such as field observation, some new water level observation technologies and methods are urgently needed to be found.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a non-contact measuring device and method for water level fluctuation process aiming at the defects of the prior art, the non-contact measuring device and method for water level fluctuation process belongs to a non-contact method, and there is no disturbance to the measuring object; the instrument is simple to erect, flexible and portable to operate, low in observation cost and suitable for complex environments and temporary observation conditions; the automation degree is high, and potential safety hazards of operation of observers do not exist.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
a non-contact measuring method for water level fluctuation process includes:
(1) setting a calibration point and a check point near the observation water level section, wherein the observation water level section vertically extends downwards to intersect with the water level line to be measured, the intersection point is a water level characteristic point of the observation water level section, and the calibration point and the check point are both positioned in the same reference plane with the water level characteristic point;
(2) measuring the actual position coordinates of the calibration point and the inspection point;
(3) laterally shooting a reference plane, wherein the calibration point and the check point are positioned in a shot image range to obtain video data of a water level change process;
(4) decomposing the video data into a series of images;
(5) correcting the image to an orthographic projection plane of the reference plane according to the calibration point of the known actual position coordinate;
(6) identifying calibration points and check points in the image, extracting pixel coordinates of the internal calibration points in the image, and calculating a conversion coefficient of the pixel coordinates and actual coordinates, namely a calibration coefficient, according to an equal ratio mapping relation of the pixel coordinates of the calibration points and the actual position coordinates of the calibration points;
(7) calculating the actual position coordinate or the elevation value of the inspection point according to the pixel coordinate of the inspection point in the image and the calibration coefficient, comparing the calculated deviation between the actual position coordinate or the elevation value of the inspection point and the measured value, and executing the step (8) when the deviation value of the actual position coordinate or the elevation value of the inspection point and the measured value is smaller than the preset deviation value;
(8) preprocessing the image;
(9) identifying instantaneous water surface characteristic points on an observation water level section in the image, calculating pixel coordinates of the water surface characteristic points in the image, and calculating actual position coordinates of the water surface characteristic points according to the pixel coordinates and the calibration coefficients of the water surface characteristic points so as to obtain actual elevation values of the water surface characteristic points, namely actual instantaneous water level values;
(10) and circularly calculating the actual elevation value of the water surface characteristic point on the observation water level section in each frame of image.
As a further improved technical solution of the present invention, the steps (1) to (10) specifically include:
(1) 4 calibration points or 2 calibration points are arranged on the section of the observed water level;
setting 4 calibration points when the four points are calibrated, wherein the calibration points are positioned at two sides of the section of the observed water level, the connecting line of the calibration points is a convex quadrangle, a check point is arranged on the section of the observed water level at the moment, the check point vertically extends downwards to be intersected with the water level line to be measured, the intersection point is a water level characteristic point of the section of the observed water level, the calibration points, the check point and the water level characteristic point are positioned in the same reference plane, and the calibration points and the check point are all higher than the highest measured water level; or:
setting 2 calibration points when the two points are calibrated, wherein the two calibration points are both arranged on an observation water level section and distributed above the highest measurement water level, the inspection point is positioned on the observation water level section and is not in common with the calibration points, the inspection point vertically extends downwards to intersect with the measured water level, the intersection point is a water level characteristic point of the observation water level section, the calibration point, the inspection point and the water level characteristic point are positioned in the same reference plane, and the calibration point and the inspection point are all higher than the highest measurement water level;
(2) measuring the actual position coordinates of the calibration point and the inspection point;
(3) selecting a camera meeting the requirement of measurement frequency, using an unmanned aerial vehicle to carry the camera, selecting the distance and the visual angle between the camera and the reference plane under the control of the console, enabling an observation water level section, a calibration point, an inspection point and an instantaneous measured water level line in the reference plane to be located in the middle of a camera shooting visual field range, and laterally shooting and recording video data of the reference plane;
(4) transmitting the acquired video data into a computer, decomposing the video data into a series of images, and selecting a first frame of image as a current image;
(5) correcting the current image to an orthographic projection plane of the reference plane according to the calibration point of the known actual position coordinate during four-point calibration, or correcting the current image to an orthographic projection plane of the observed water level section during two-point calibration;
(6) identifying a calibration point and a check point in a current image, extracting a pixel coordinate of a calibration point in the current image, and calculating a conversion coefficient of the pixel coordinate and an actual position coordinate, namely a calibration coefficient, according to an equal ratio mapping relation of the pixel coordinate of the calibration point and the actual position coordinate of the calibration point;
(7) calculating the actual position coordinate or the elevation value of the inspection point according to the pixel coordinate of the inspection point in the current image and the calibration coefficient, comparing the calculated deviation between the actual position coordinate or the elevation value of the inspection point and the measured value, and executing the step (8) when the deviation value of the actual position coordinate or the elevation value of the inspection point and the measured value is smaller than the preset deviation value;
(8) preprocessing a current image;
(9) identifying instantaneous water surface characteristic points of an observation water level section in a current image, calculating pixel coordinates of the instantaneous water surface characteristic points in the current image, calculating actual position coordinates of the instantaneous water surface characteristic points according to the pixel coordinates of the instantaneous water surface characteristic points and a calibration coefficient, and further obtaining actual elevation values of the instantaneous water surface characteristic points, namely actual instantaneous water level values;
(10) judging whether the current image is the last frame image or not, if not, selecting the next frame image as the current image, returning to the step (5), and if so, executing the step (11);
(11) and calculating the average value, the maximum value, the minimum value and the turbulent root mean square value of the water level change process according to the actual instantaneous water level elevation value of the water surface feature point of the calculated image.
In order to achieve the technical purpose, the invention adopts another technical scheme as follows:
the utility model provides a water level fluctuation process non-contact measuring device, is including setting up in a plurality of calibration points, camera and the computer of same reference plane, the calibration point is located the top of the highest measured water level, camera frequency and pixel satisfy discernment water level definition and water level sampling frequency, shoot video data and transmit to the computer in, the computer is used for handling video data.
As a further improved technical scheme of the invention, the camera is carried on the unmanned aerial vehicle, and the unmanned aerial vehicle carries the camera to shoot the reference plane.
The invention has the beneficial effects that:
(1) the invention is a non-contact measuring method, which has no external disturbance to the observed water body and the water level change process and ensures the authenticity of data.
(2) According to the invention, the observation instrument device (namely the camera) is arranged laterally, so that the space and flexibility of the temporary arrangement instrument are increased, the unmanned aerial vehicle carrying the camera can flexibly acquire video data in all directions, the difficulty of temporary observation caused by complex conditions on site is overcome, the flexibility is higher, and the potential safety hazard of installation and use of measuring personnel and instruments is greatly avoided; when the computer carries out post-processing, the image is corrected in real time, the pixel coordinates and the calibration coefficient of the internal standard fixed point of each frame of image are calculated in real time, and the defect of aerial positioning swing of the unmanned aerial vehicle is overcome.
(3) The invention obtains the video data of the observed water level in the reference plane by a camera shooting method, corrects the oblique visual angle image by a four-point calibration method, matches the oblique visual angle image with the actual coordinate, searches the characteristic point of the detected water level based on an image recognition technology, calculates the instantaneous water level of the characteristic point of the detected water level, and flexibly and closely obtains the water level change process of the observed object by an unmanned aerial vehicle carrying a camera if necessary. The obtained water level elevation data has good continuity, high frequency and high precision, the maximum frequency is the same as the frame rate of the camera, the precision and the frequency are far higher than those of a method for manually reading a water gauge, the automation degree is high, and the field workload is greatly reduced.
(4) The instrument is simple to erect, portable to operate and low in observation cost, and is suitable for complex observation environments; the automation degree is high, and the potential safety hazard of temporary observation personnel operation does not exist.
Drawings
Fig. 1 is a schematic structural view of embodiment 1.
Fig. 2 is a schematic structural view of embodiment 2.
Fig. 3 is a schematic structural view of embodiment 3.
FIG. 4 is a computer processing flow diagram.
Detailed Description
The following further describes embodiments of the present invention with reference to fig. 1 to 4:
example 1: referring to fig. 1, the present embodiment provides a non-contact measuring device for water level fluctuation process, which includes four calibration points 5 and a check point 6 disposed on the same reference plane, a laterally disposed camera 7 and a computer. The calibration points 5 are used for correcting images to an orthographic projection plane, the check points 6 are used for detecting the calculation accuracy, the camera 7 is used for shooting a reference plane and transmitting the shot video data to a computer, and the computer is used for recognizing and analyzing the video data by adopting an image recognition technology. Before actual measurement, a calibration point 5 and a check point 6 need to be arranged near an observation water level section, the calibration point 5 and the check point 6 are required to be arranged in the same reference plane with an observation water surface object, a plane retaining wall body or a bank slope can be used as the reference plane, and if no existing reference plane exists, a marker or a vertical scale can be arranged near the water surface to construct the reference plane.
The specific method comprises the following steps:
a non-contact measuring method for water level fluctuation process includes:
(1) set up index point 5 and check point 6 near observing the water level section, index point 5 and check point 6 all are located same reference plane with surveyed water level line 1, if barricade, pier stud or artificially set up scale etc. mark index point 5 and check point 6 in the reference plane (index point 5 and check point 6 can be current characteristic point, appear in camera 7 field of vision during the measurement, and can discern its mark), the index point 5 of this embodiment is four, is respectively point B in figure 11~B4The check point 6 is selected from the observation water level section 2 and is located above the highest measurement water level 4, and the check point 6 is a point J in fig. 11The inspection point 6 extends vertically downwards to intersect with the measured water surface line 1, and the intersection point t is a measured water surface characteristic point 3; the positions of the calibration points 5 in this embodiment are all higher than the highest measurement water level 4 (the highest water level of the water surface line) so as to prevent the calibration points 5 from being invisible in the visual field during measurement. Particularly, 4 calibration points 5 are located on two sides of the observation section 2, 2 calibration points 5 are respectively arranged, the 4 calibration points 5 are distributed in a convex quadrilateral shape in a scattered mode, and the distance is increased, so that the measurement object is located in the area between the calibration points.
(2) Measuring the actual position coordinates of the calibration point 5 and the inspection point 6 by using instruments such as a total station; the method is used for establishing and checking a conversion relation between the actual coordinate and the pixel coordinate.
(3) Laterally shooting a reference plane by using a single-lens reflex camera to obtain video data;
the method specifically comprises the following steps: the camera 7 is a long-focus single-lens reflex camera, pixels 6000pix and 4000pix have the shooting frequency of 30Hz, the shooting points are arranged opposite to the reference plane, and the reference plane is shot laterally. When shooting and recording video, the observation water level section 2 needs to be positioned in the middle of the camera view field range, and the point 5 (point B) needs to be calibrated1~B4) The four points are dispersed around the center of the visual field (the area enclosed by the calibration points occupies more than half of the total area of the image), so that the calculation precision can be improved, and preferably, the camera is kept fixed in the shooting process.
(4) Decomposing video data into a series of images, selecting images according to a time sequence change process, and firstly selecting a frame of image as a current image.
(5) And correcting the current image by a perspective transformation method and a four-point calibration method, and correcting the reference plane image which is taken in a downward manner or in an oblique manner to an orthographic projection plane.
(6) Identifying the index point 5 (point B) within the rectified image1~B4) And check Point 6 (Point J)1) And calculating the pixel coordinate of the internal standard point 5 in the current image, and performing matching calculation on the pixel coordinate of the standard point 5 and the actual position coordinate of the standard point 5 to obtain a calibration coefficient.
(7) And (3) calculating the actual position coordinate or the elevation value of the inspection point 6 according to the pixel coordinate of the inspection point 6 in the current image and the pixel coordinate of the inspection point 6 and the calibration coefficient, comparing the calculated value or the elevation value of the actual position coordinate of the inspection point 6 with the measured value, calculating the deviation value of the actual position coordinate or the elevation value of the inspection point 6 and the measured value, executing the step (8) when the deviation value of the actual position coordinate or the elevation value of the inspection point is smaller than the preset deviation value, and jumping out of the.
(8) Preprocessing a current image, comprising: setting ROI region-graying-binarization-on operation, etc.
(9) Identifying water surface characteristic points 3 on an observation water level section in a current image, calculating pixel coordinates of the water surface characteristic points 3 in the image, calculating actual position coordinates of the water surface characteristic points 3 according to a calibration coefficient and the pixel coordinates of the detected water surface characteristic points 3, and further acquiring actual elevation values of the water surface characteristic points 3;
(10) and (3) selecting the next frame of image of the current image according to the time sequence change process, taking the selected next frame of image as the current image, and calculating the actual elevation value of the water surface feature point 3 in the next frame of image according to the steps (5) to (9), wherein the calibration coefficients of the calculation of the calibration coefficient in the step (6) and the deviation test in the step (7) can be omitted because the camera of the camera 7 in the embodiment is fixed, namely the calibration coefficients of each frame of image are consistent. The water level fluctuation process can be obtained through the actual instantaneous elevation value of the water surface characteristic point 3 corresponding to each frame of image in the video data, and characteristic analysis is carried out on the water level process data.
Example 2: referring to fig. 2, the non-contact measuring device for the water level fluctuation process provided by the embodiment comprises four calibration points 5 and a check point 6 which are arranged on the same reference plane, and a camera 7 and a computer which are arranged laterally. The calibration points 5 are used for correcting images to an orthographic projection plane, the check points 6 are used for detecting the calculation accuracy, the camera 7 is used for shooting a reference plane and transmitting the shot video data to a computer, and the computer is used for recognizing and analyzing the video data by adopting an image recognition technology. The difference with embodiment 1 is that the camera 7 adopts unmanned aerial vehicle to carry and make a video recording, when the stadia is great or should not erect the camera instrument, can use unmanned aerial vehicle to carry camera 7 and obtain the video data that satisfies the requirement, camera 7 fixes on unmanned aerial vehicle promptly, to unconditionally setting camera observation point or observation point position is not good or when interim short-term measurement under the complex environment, like the on-the-spot observation project of runner broad, bank slope steepness, especially show its superiority and flexibility. Simultaneously, the unmanned aerial vehicle carries the camera 7 to shoot a test object at any angle in a short distance, so that the requirements on the performance and parameters of the camera are greatly reduced, and convenience and guarantee are provided for instrument installation and personnel safety. Of course, the unmanned aerial vehicle also has its own shortcoming, if the location is unstable when aerial is made a video recording, the camera has little displacement change when taking a picture in succession, needs to correct respectively and the deviation inspection to every frame image this moment to satisfy the measurement accuracy requirement.
The specific method comprises the following steps:
a non-contact measurement method for water level fluctuation process, comprising, referring to fig. 4:
(1) four calibration points 5 (point B) are arranged near the observation water level section 21~B4) And checkpoint 6 (J)1) The calibration points 5 and the inspection points 6 are both located in the same reference plane with the water surface line 1 to be measured, such as a retaining wall, a pier column or a manual scale. Marking the index points 5 and the check points 6 in the reference plane (the index points 5 and the check points 6 can be the existing characteristic points, appear in the visual field of the unmanned aerial vehicle carrying camera 7 during measurement, and can identify the marks), the index points 5 are positioned at two sides of the observation water level section 2 in the reference plane, two index points 5 and four index points 5 are respectively arranged at two sides of the observation water level section 2 (point B)1~B4) The measuring object area is distributed in a convex quadrilateral shape, and the distance is increased, so that the measuring object area is located between the calibration points. The inspection point 6 vertically extends downwards to intersect with the measured water level line 1, the intersection point t is a measured water level feature point 3, the measured water level feature point 3 and the inspection point 6 are both located on the observation water level section 2, and the inspection point 6 and the four calibration points 5 are both higher than the highest measurement water level 4.
(2) Measuring the calibration point 5 (point B) by using instruments such as a total station1~B4) And checkpoint 6 (J)1) Actual position coordinates of (a); the method is used for coefficient calibration and error detection during image processing.
(3) Select the high definition camera that satisfies the measuring frequency requirement, camera 7 carries on unmanned aerial vehicle, by the flying hand remote control, unmanned aerial vehicle carries camera 7 and under the manipulation of controlling the platform, and the reference plane is shot to the side direction, establishes the condition according to reality and selects the camera performance, and this embodiment camera 7 carries on unmanned aerial vehicle, and unmanned aerial vehicle hovers positional stability at 5cm within range, camera fixed focal length, pixel 4000pix 3000pix, frame rate 30 Hz. Preferably, when shooting and recording a video, the distance and the visual angle between the camera and the reference plane are flexibly selected under the operation of the console, so that the observation water level section 2 in the reference plane is positioned in the middle of the shooting visual field range and is clearly visible; index point 5 (point B)1~B4) Is/are as followsFour points are dispersed around the center of the visual field (the area enclosed by the calibration points accounts for more than half of the total area of the visual field of the shot picture), so that the calculation precision can be improved.
(4) The unmanned aerial vehicle carries the camera 7 to transmit the acquired video data to the computer, the computer adopts the image recognition technology to recognize and analyze the target form and the dynamic characteristics in the video data, referring to fig. 3, the computer decomposes the video data into a series of images, and selects a frame of image as the current image.
(5) The method comprises the steps of correcting a current image by a perspective transformation method and a four-point calibration method, correcting a reference plane image which is shot in a downward direction or in an oblique direction by an unmanned aerial vehicle to an orthographic projection plane, and correcting each frame of image due to hovering swing of the unmanned aerial vehicle. .
(6) Identifying the index point 5 (point B) within the rectified image1~B4) And checkpoint 6 (J)1) And calculating the pixel coordinate of the internal standard point 5 of the current image, matching the pixel coordinate of the standard point 5 with the actual position coordinate of the standard point 5, and calculating the conversion coefficient of the pixel coordinate and the actual position coordinate, namely the calibration coefficient.
(7) And (4) calculating the actual position coordinate or the elevation value of the inspection point 6 according to the pixel coordinate of the inspection point 6 in the current image through the calibration coefficient and the pixel coordinate of the inspection point 6, comparing the deviation between the actual position coordinate or the elevation value of the inspection point obtained by calculation and the measured value, calculating the deviation value of the actual position coordinate or the elevation value of the inspection point and the measured value, and executing the step (8) when the deviation value of the actual position coordinate or the elevation value of the inspection point and the measured value is smaller than the preset deviation value.
(8) Preprocessing a current image, comprising: setting ROI region-graying-binarization-on operation, etc.
(9) Identifying the instantaneous water surface characteristic points 3 of the observation water level section in the current image, calculating the pixel coordinates of the instantaneous water surface characteristic points 3, calculating the actual position coordinates of the water surface characteristic points 3 according to the calibration coefficient and the pixel coordinates of the instantaneous water surface characteristic points 3, and further acquiring the actual elevation value of the water surface characteristic points 3, namely the actual instantaneous water level value.
(10) And (5) judging whether the current image is the last frame image, if not, selecting the next frame image of the current image according to the time sequence order and returning to execute the step (5), and if so, executing the step (11). Because the unmanned aerial vehicle is unstable in positioning during aerial photography and the camera has small displacement change during continuous photography, the calibration coefficient corresponding to each frame of image in the embodiment needs to be recalculated, and the deviation value also needs to be rechecked.
(11) And obtaining a water level fluctuation process through the actual elevation value of the measured water surface characteristic point 3 corresponding to each frame of image in the video data, and calculating characteristic values such as an average value, a maximum value, a minimum value, a turbulent fluctuation root mean square value and the like of the water level fluctuation process.
In the post-processing, each frame of image is corrected in real time, and the pixel coordinates and the calibration coefficients of the calibration points in each frame of image are calculated, so that the defect of aerial positioning swing of the unmanned aerial vehicle is overcome.
Example 3: referring to fig. 3, the present embodiment provides a non-contact measuring device for water level fluctuation process, which includes two calibration points 5 and a check point 6 disposed on the same reference plane, a laterally disposed camera 7 and a computer. The calibration points 5 are used for correcting images to an orthographic projection plane, the check points 6 are used for detecting the calculation accuracy, the camera 7 is used for shooting a reference plane and transmitting the shot video data to a computer, and the computer is used for recognizing and analyzing the video data by adopting an image recognition technology.
The difference from the embodiment 1 is that the camera 7 is carried and shot by an unmanned aerial vehicle, and the two calibration points 5 are positioned on the observation water level section 2 together with the inspection point 6; the difference from example 2 is that the number of the index points 5 is two, and the others are the same. And 2 calibration points 5 are arranged at two calibration points, at the moment, the two calibration points 5 are arranged on the observation water level section 2 and distributed above the highest measurement water level 2, the inspection point 6 is positioned on the observation water level section and is not in common with the calibration points 5, the inspection point 6 vertically extends downwards to intersect with the measured water level 1, the intersection point is a water level characteristic point 3 of the observation water level section 2, and the calibration points 5, the inspection point 6 and the water level characteristic point 3 are positioned in the same reference plane. The method is suitable for measuring the water level process of the cross section of the scale when the reference plane is not well selected (such as two banks of a natural river) and the scale needs to be manually arranged, four-point calibration is not needed, 1 marker post is vertically arranged and scale marking is carried out. The unmanned aerial vehicle is combined to flexibly obtain the water level change image, a large amount of equipment and labor cost can be avoided, the use is not influenced even if the river surface is wider, and the advantages of the method are highlighted.
The specific non-contact measurement method of this embodiment is substantially the same as that of embodiment 2, only the number of the calibration points 5 is reduced to two, and two calibration points 5 and one inspection point 6 are required to be both on the observed water level cross section 2, and when the two calibration points are calibrated on the corrected image, the corrected image is aligned with the orthographic projection line of the observed water level cross section. The calculation of coordinates is only required to calculate the vertical coordinate values, and it can be considered that embodiment 2 is two-dimensional, and embodiment 3 is one-dimensional.
The scope of the present invention includes, but is not limited to, the above embodiments, and the present invention is defined by the appended claims, and any alterations, modifications, and improvements that may occur to those skilled in the art are all within the scope of the present invention.
Claims (1)
1. The non-contact measuring method for the water level fluctuation process is characterized by comprising the following steps:
(1) 4 calibration points or 2 calibration points are arranged on the section of the observed water level;
setting 4 calibration points when the four points are calibrated, wherein the calibration points are positioned at two sides of the section of the observed water level, the connecting line of the calibration points is a convex quadrangle, a check point is arranged on the section of the observed water level at the moment, the check point vertically extends downwards to be intersected with the water level line to be measured, the intersection point is a water level characteristic point of the section of the observed water level, the calibration points, the check point and the water level characteristic point are positioned in the same reference plane, and the calibration points and the check point are all higher than the highest measured water level;
or:
setting 2 calibration points when the two points are calibrated, wherein the two calibration points are both arranged on an observation water level section, the inspection point is positioned on the observation water level section and is not in common with the calibration points, the inspection point vertically extends downwards to be intersected with a measured water level line, the intersection point is a water level characteristic point of the observation water level section, the calibration point, the inspection point and the water level characteristic point are positioned in the same reference plane, and the calibration point and the inspection point are all higher than the highest measurement water level;
the calibration points and the inspection points are the existing characteristic points, appear in the visual field of the camera during measurement, and can identify the marks of the calibration points and the inspection points;
(2) measuring the actual position coordinates of the calibration point and the inspection point;
(3) selecting a camera meeting the requirement of measurement frequency, using an unmanned aerial vehicle to carry the camera, selecting the distance and the visual angle between the camera and the reference plane under the control of the console, enabling an observation water level section, a calibration point, an inspection point and an instantaneous measured water level line in the reference plane to be located in the middle of a camera shooting visual field range, and laterally shooting and recording video data of the reference plane;
(4) transmitting the acquired video data into a computer, selecting images according to a time sequence change process, decomposing the video data into a series of images, and selecting a first frame of image as a current image;
(5) when the four-point calibration is performed, correcting the current image to the orthographic projection plane of the reference plane according to the calibration point of the known actual position coordinate, and correcting each frame of image when the unmanned aerial vehicle is adopted for shooting; or correcting the orthographic projection line from the current image to the observation water level section when two points are calibrated;
(6) identifying a calibration point and a check point in a current image, extracting a pixel coordinate of a calibration point in the current image, and calculating a conversion coefficient of the pixel coordinate and an actual position coordinate, namely a calibration coefficient, according to an equal ratio mapping relation of the pixel coordinate of the calibration point and the actual position coordinate of the calibration point;
(7) calculating the actual position coordinate or the elevation value of the inspection point according to the pixel coordinate of the inspection point in the current image and the calibration coefficient, comparing the calculated deviation between the actual position coordinate or the elevation value of the inspection point and the measured value, and executing the step (8) when the deviation value of the actual position coordinate or the elevation value of the inspection point and the measured value is smaller than the preset deviation value;
(8) preprocessing a current image, and setting ROI (region of interest) -graying-binaryzation-opening operation;
(9) identifying instantaneous water surface characteristic points of an observation water level section in a current image, calculating pixel coordinates of the instantaneous water surface characteristic points in the current image, calculating actual position coordinates of the instantaneous water surface characteristic points according to the pixel coordinates of the instantaneous water surface characteristic points and a calibration coefficient, and further obtaining actual elevation values of the instantaneous water surface characteristic points, namely actual instantaneous water level values;
(10) judging whether the current image is the last frame image or not, if not, selecting the next frame image as the current image, returning to the step (5), and if so, executing the step (11);
(11) calculating the average value, the maximum value, the minimum value and the turbulent root mean square value of the water level change process according to the actual instantaneous water level elevation value of the water surface feature point of the calculated image;
the device comprises a plurality of calibration points, a camera and a computer which are arranged on the same reference plane, wherein the calibration points are positioned above the highest measured water level, the frequency and the pixel of the camera meet the requirements of identifying the definition of the water level and the sampling frequency of the water level, shot video data are transmitted into the computer, and the computer is used for processing the video data;
the camera is carried on the unmanned aerial vehicle, and the unmanned aerial vehicle carries the camera to shoot the reference plane; during continuous shooting, the displacement of the camera changes, each frame of image is respectively corrected and subjected to deviation inspection so as to meet the requirement of measurement accuracy, each frame of image is corrected in real time, the coordinate of a calibration point pixel and a calibration coefficient in each frame of image are calculated, and the defect of aerial positioning swing of the unmanned aerial vehicle is overcome.
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