CN110807458A - Automatic reading method for pointer instrument - Google Patents
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- CN110807458A CN110807458A CN201911020869.1A CN201911020869A CN110807458A CN 110807458 A CN110807458 A CN 110807458A CN 201911020869 A CN201911020869 A CN 201911020869A CN 110807458 A CN110807458 A CN 110807458A
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- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000001514 detection method Methods 0.000 claims abstract description 12
- 238000003708 edge detection Methods 0.000 claims abstract description 4
- 238000007781 pre-processing Methods 0.000 claims abstract description 4
- 238000001914 filtration Methods 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 claims description 4
- 230000009466 transformation Effects 0.000 claims description 4
- 230000002146 bilateral effect Effects 0.000 claims description 3
- GNFTZDOKVXKIBK-UHFFFAOYSA-N 3-(2-methoxyethoxy)benzohydrazide Chemical compound COCCOC1=CC=CC(C(=O)NN)=C1 GNFTZDOKVXKIBK-UHFFFAOYSA-N 0.000 claims description 2
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/20—Image preprocessing
- G06V10/25—Determination of region of interest [ROI] or a volume of interest [VOI]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/40—Image enhancement or restoration using histogram techniques
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/70—Denoising; Smoothing
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/10—Segmentation; Edge detection
- G06T7/13—Edge detection
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/60—Analysis of geometric attributes
- G06T7/62—Analysis of geometric attributes of area, perimeter, diameter or volume
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/20—Image preprocessing
- G06V10/26—Segmentation of patterns in the image field; Cutting or merging of image elements to establish the pattern region, e.g. clustering-based techniques; Detection of occlusion
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V2201/00—Indexing scheme relating to image or video recognition or understanding
- G06V2201/02—Recognising information on displays, dials, clocks
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Abstract
The invention relates to an automatic reading method for a pointer instrument, which comprises the steps of initializing dial information, preprocessing an image, carrying out Hough ellipse detection to obtain a region to be detected, obtaining the relative positions of a current pressure pointer, a low-pressure threshold pointer and a high-pressure threshold pointer through the steps of edge detection by using a Canny operator, Hough straight line detection algorithm and the like, and automatically reading the reading of the current pressure pointer. Compared with the prior art, the technical scheme of the invention not only can identify the low-pressure threshold pointer and the high-pressure threshold pointer and read the reading indicated by the pressure pointer, but also can be further used for low-pressure and high-pressure alarm based on the reading, thereby improving the use efficiency of the pointer instrument.
Description
Technical Field
The invention relates to the technical field of pointer instruments, in particular to an automatic reading method of a pointer instrument.
Background
The pointer type instrument is used in the respective air pressure detection field, the air pressure of the existing pointer type instrument is usually identified by manual work, when the pressure is low, manual pressurization is carried out, when the pressure is high, manual decompression is carried out, human factors are indispensable, and a specially-assigned person is required to be arranged to monitor the pressure so as to adjust the pressure.
Chinese patent CN107145890A discloses an automatic reading method for pointer type instrument panel under remote multi-view environment, which comprises the steps of dial area determination, segmentation processing, pointer extraction fitting and reading estimation. Firstly, determining a dial area in an image by matching an image to be recognized and key points of a template dial, then distributing a binary dial according to a histogram, obtaining dial internal information by performing morphological processing on the binary image, then summing and merging straight lines obtained by probability Hough transform fitting to obtain a pointer angle, and finally calculating a pointer reading according to a prior pointer. The technology designs matrix transformation, the calculation is slightly complicated, and low-voltage pointers and high-voltage pointers cannot be identified. Based on the problems of this technology, the present invention has been developed.
Disclosure of Invention
The invention aims at the technical problem and provides an automatic reading method for a pointer instrument.
In order to achieve the purpose, the specific technical scheme of the invention is as follows:
an automatic reading method for a pointer instrument comprises the following steps:
a. initializing meter dial information to obtain value v expressed by dial unit angle, and low-voltage and high-voltage alarm threshold values are respectively T1、T2As prior information;
b. inputting a dial plate image to be read, and performing noise reduction pretreatment on the image;
c. carrying out Hough ellipse detection on the preprocessed image, and positioning a dial target area; then, perspective transformation is carried out according to the ellipse to obtain a circular top view of the dial and the circle center (x) of the dial0，y0) And radius R0；
d. Obtaining a region to be detected according to the circular region of the changed dial plate, wherein the region to be detected is R0-Tr＜(x-x0)2+(y-y0)2＜R0Wherein T isrIs a settable radius threshold;
e. carrying out edge detection on the area to be detected by using a Canny operator to obtain an edge image of the area to be detected;
f. performing linear detection on the edge image of the area to be detected by using a Hough linear detection algorithm, and filtering line segments with the length smaller than a preset length threshold;
g. merging straight lines with approximate intercept and slope;
h. deleting a straight line which is too far away from the circle center; let the equation of a straight line be y ═ ax + b, if | ax0+b-y0|＞ToThen delete the line, where ToIs a distance threshold;
i. sorting all the remaining straight lines according to length, selecting three straight lines with the longest length as candidate pointer fitting straight lines, sorting according to length, and recording the lengths as L1, L2 and L3 respectively, wherein L1 is more than L2 is more than L3;
if L3 is less than L2/3, the pointer of the current pressure gauge is overlapped with the pointer of the upper threshold value and the lower threshold value, the straight line is deleted, and an alarm is output;
if L3 is more than or equal to L2/3, judging that the three lines are all fitting straight lines, calculating included angles between every two of the three straight lines, and if the included angle theta between the two straight lines is equal to | T ≧ T2-T1If yes, judging that the two straight lines are fitting straight lines of the two threshold pointers, and the rest straight lines are fitting straight lines of the pressure pointers;
j. respectively calculating the included angle between the fitting straight line of the pressure pointer and the fitting straight lines of the two threshold pointers, and setting the included angle between the fitting straight lines of the pressure pointer and the fitting straight lines of the two threshold pointers as theta1And the included angle between the high-voltage pointer and the high-voltage pointer is theta2Then, the calculation formula of the current pressure is as follows:
P＝(T2+T1+θ1*v+θ2*v)/2。
preferably, in the step b, the noise reduction preprocessing performed on the image includes noise reduction processing and histogram equalization, first, bilateral filtering is used to remove noise in the original image, and then histogram equalization is used to enhance the contrast of the image.
Preferably, in step f, the preset length threshold is 2/3 indicating the length of the pointer of the current pressure.
Preferably, in step g, the judgment basis for merging the straight lines with approximate intercepts and slopes is as follows:
let two linear equations be y ═ a respectively1x+b1、y＝a2x+b2(ii) a If a1-a2< Ta and | b1-b2|＜TbThen, the two straight lines are merged, and the merged straight line equation is that y ═ a1+a2)/2*x+(b1+b2) 2; wherein T isaAnd TbRespectively, the threshold values of slope and intercept.
Preferably, the automatic reading method further comprises a step k of alarming:
k. judging the current pressure P and the threshold value T1、T2Judging whether to output an alarm or not according to the magnitude relation; when P < T1When the pressure is higher than the preset value, a low-pressure alarm is sent out, and when P is more than T2When it is in high voltage, when T1＜P＜T2Only the pressure result is output and no alarm is sent.
Preferably, in said step d, TrIn relation to the size of the screw cap for holding the pointer in the centre of the meter, e.g. TrThe radius of the nut can be set to be 1-N times (N is a positive integer, and the radius of the nut N times is less than R0)。
Compared with CN107145890A and other prior arts, the invention can identify the low pressure threshold pointer and the high pressure threshold pointer and read the reading indicated by the pressure pointer, and can be used for low pressure and high pressure alarm based on the reading, thereby improving the use efficiency of the pointer instrument.
Detailed Description
In order that those skilled in the art will be able to understand and practice the present invention, further description will be given below of embodiments of the present invention.
The invention provides an automatic reading method of a pointer instrument, which comprises the following specific processes:
an automatic reading method for a pointer instrument comprises the following steps:
1. initializing the dial information of the instrument, and obtaining the value v, low voltage, voltage and angle of the dial,The high-voltage alarm threshold is T1、T2As prior information;
2. inputting a dial plate image to be read, and performing noise reduction pretreatment on the image; the image noise reduction preprocessing comprises noise reduction processing and histogram equalization; firstly, removing noise in an original image by utilizing bilateral filtering, and then enhancing the contrast of the image by utilizing histogram equalization;
3. carrying out Hough ellipse detection on the preprocessed image, and positioning a dial target area; then, perspective transformation is carried out according to the ellipse to obtain a circular top view of the dial and the circle center (x) of the dial0，y0) And radius R0；
4. The electric contact pressure gauge is provided with an upper limit threshold pointer, a lower limit threshold pointer and a pressure indicator, wherein the three pointers are used for acquiring a to-be-detected area according to a circular area of the changed dial plate, and the to-be-detected area is R0-Tr＜(x-x0)2+(y-y0)2＜R0Wherein T isrIs a settable radius threshold; t isrIn relation to the size of the screw cap for holding the pointer in the centre of the meter, e.g. TrThe radius of the nut can be set to be 1-N times (N is a positive integer, and the radius of the nut N times is less than R0)。
5. Carrying out edge detection on the area to be detected by using a Canny operator to obtain an edge image of the area to be detected;
6. performing linear detection on an edge image of a region to be detected by using a Hough linear detection algorithm, and filtering line segments with too small lengths, specifically, setting a preset length threshold as 2/3 of the length of a pointer indicating the current pressure, and filtering line segments with lengths smaller than the preset length threshold;
7. merging straight lines with approximate intercept and slope; the judgment basis for merging the straight lines with approximate intercept and slope is as follows:
let two linear equations be y ═ a respectively1x+b1、y＝a2x+b2(ii) a If a1-a2|＜TaAnd | b1-b2|＜TbThen proceed to two straight linesMerging, and the merged linear equation is that y is equal to (a)1+a2)/2*x+(b1+b2) 2; wherein T isaAnd TbRespectively, the threshold values of slope and intercept.
8. Deleting a straight line which is too far away from the circle center; let the equation of a straight line be y ═ ax + b, if | ax0+b-y0|＞ToThen delete the line, where ToIs a distance threshold;
9. sorting all the remaining straight lines according to length, selecting three straight lines with the longest length as candidate pointer fitting straight lines, sorting according to length, and recording the lengths as L1, L2 and L3 respectively, wherein L1 is more than L2 is more than L3;
if L3 is less than L2/3, the pointer of the current pressure gauge is overlapped with the pointer of the upper threshold value and the lower threshold value, the straight line is deleted, and an alarm is output;
if L3 is more than or equal to L2/3, judging that the three lines are all fitting straight lines, calculating included angles between every two of the three straight lines, and if the included angle theta between the two straight lines is equal to | T ≧ T2-T1If yes, judging that the two straight lines are fitting straight lines of the two threshold pointers, and the rest straight lines are fitting straight lines of the pressure pointers;
10. respectively calculating the included angle between the fitting straight line of the pressure pointer and the fitting straight lines of the two threshold pointers, and setting the included angle between the fitting straight lines of the pressure pointer and the fitting straight lines of the two threshold pointers as theta1And the included angle between the high-voltage pointer and the high-voltage pointer is theta2Then, the calculation formula of the current pressure is as follows:
P＝(T2+T1+θ1*v+θ2*v)/2。
as a preferred embodiment of the present invention, the automatic reading method further comprises the step of alarming:
11. judging the current pressure P and the threshold value T1、T2Judging whether to output an alarm or not according to the magnitude relation; when P < T1When the pressure is higher than the preset value, a low-pressure alarm is sent out, and when P is more than T2When it is in high voltage, when T1＜P＜T2Only the pressure result is output and no alarm is sent.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (6)
1. An automatic reading method for a pointer instrument is characterized by comprising the following steps:
a. initializing meter dial information to obtain value v expressed by dial unit angle, and low-voltage and high-voltage alarm threshold values are respectively T1、T2As prior information;
b. inputting a dial plate image to be read, and performing noise reduction pretreatment on the image;
c. carrying out Hough ellipse detection on the preprocessed image, and positioning a dial target area; then, perspective transformation is carried out according to the ellipse to obtain a circular top view of the dial and the circle center (x) of the dial0，y0) And radius R0；
d. Obtaining a region to be detected according to the circular region of the changed dial plate, wherein the region to be detected is R0-Tr＜(x-x0)2+(y-y0)2＜R0Wherein T isrIs a settable radius threshold;
e. carrying out edge detection on the area to be detected by using a Canny operator to obtain an edge image of the area to be detected;
f. performing linear detection on the edge image of the area to be detected by using a Hough linear detection algorithm, and filtering line segments with the length smaller than a preset length threshold;
g. merging straight lines with approximate intercept and slope;
h. deleting a straight line which is too far away from the circle center; let the equation of a straight line be y ═ ax + b, if | ax0+b-y0|＞ToThen delete the line, where ToIs a distance threshold;
i. sorting all the remaining straight lines according to length, selecting three straight lines with the longest length as candidate pointer fitting straight lines, sorting according to length, and recording the lengths as L1, L2 and L3 respectively, wherein L1 is more than L2 is more than L3;
if L3 is less than L2/3, the pointer of the current pressure gauge is overlapped with the pointer of the upper threshold value and the lower threshold value, the straight line is deleted, and an alarm is output;
if L3 is more than or equal to L2/3, judging that the three lines are all fitting straight lines, calculating included angles between every two of the three straight lines, and if the included angle theta between the two straight lines is equal to | T ≧ T2-T1If yes, judging that the two straight lines are fitting straight lines of the two threshold pointers, and the rest straight lines are fitting straight lines of the pressure pointers;
j. respectively calculating the included angle between the fitting straight line of the pressure pointer and the fitting straight lines of the two threshold pointers, and setting the included angle between the fitting straight lines of the pressure pointer and the fitting straight lines of the two threshold pointers as theta1And the included angle between the high-voltage pointer and the high-voltage pointer is theta2Then, the calculation formula of the current pressure is as follows:
P＝(T2+T1+θ1*v+θ2*v)/2。
2. the pointer instrument automatic reading method as claimed in claim 1, wherein in the step b, the image is subjected to noise reduction preprocessing including noise reduction processing and histogram equalization, firstly bilateral filtering is used to eliminate noise in the original image, and then histogram equalization is used to enhance the contrast of the image.
3. According to claim 1Or 2The method for automatically reading the pointer instrument is characterized in that in the step f, the preset length threshold is 2/3 of the length of the pointer indicating the current pressure.
4. According to claim 1Or 2The automatic reading method of the pointer instrument is characterized in that in the step g, the judgment basis for merging straight lines with approximate intercept and slope is as follows:
let two linear equations be y ═ a respectively1x+b1、y＝a2x+b2；
If a1-a2|＜TaAnd | b1-b2|＜TbThen, the two straight lines are merged, and the equation of the merged straight line is:
y＝(a1+a2)/2*x+(b1+b2)/2；
wherein T isaAnd TbRespectively, the threshold values of slope and intercept.
5. The pointer instrument automatic reading method according to claim 1 or 2, characterized in that the automatic reading method further comprises a step k of alarming:
k. judging the relation between the current pressure P and the threshold values T1 and T2, and judging whether to output an alarm or not according to the size relation; when P < T1, a low pressure alarm is issued, when P > T2, a high pressure alarm is issued, when T1 < P < T2, only the pressure result is output, and no alarm is issued.
6. The pointer instrument automatic reading method as claimed in claim 1 or 2, characterized in that in the step d, T isrEqual to the radius of the size of the nut holding the pointer in the center of the meter.
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| CN201911020869.1A CN110807458A (en) | 2019-10-24 | 2019-10-24 | Automatic reading method for pointer instrument |
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| CN201911020869.1A CN110807458A (en) | 2019-10-24 | 2019-10-24 | Automatic reading method for pointer instrument |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111797909A (en) * | 2020-06-22 | 2020-10-20 | 上海工程技术大学 | Pointer instrument reading method based on machine vision |
| CN112036391A (en) * | 2020-07-22 | 2020-12-04 | 四川长宁天然气开发有限责任公司 | Electronic inspection method and system based on shale gas field production station |
| CN112036390A (en) * | 2020-07-22 | 2020-12-04 | 四川长宁天然气开发有限责任公司 | Identification method for reading of three-pin instrument based on shale gas field production |
| CN115655576A (en) * | 2022-12-13 | 2023-01-31 | 成都千嘉科技股份有限公司 | Automatic sensing method for displacement abnormity of pointer type pressure gauge |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111797909A (en) * | 2020-06-22 | 2020-10-20 | 上海工程技术大学 | Pointer instrument reading method based on machine vision |
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| CN112036391A (en) * | 2020-07-22 | 2020-12-04 | 四川长宁天然气开发有限责任公司 | Electronic inspection method and system based on shale gas field production station |
| CN112036390A (en) * | 2020-07-22 | 2020-12-04 | 四川长宁天然气开发有限责任公司 | Identification method for reading of three-pin instrument based on shale gas field production |
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