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CN111739048B - Icing wind tunnel test ice-shaped geometric contour line digitalization method - Google Patents

Icing wind tunnel test ice-shaped geometric contour line digitalization method Download PDF

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CN111739048B
CN111739048B CN202010728466.9A CN202010728466A CN111739048B CN 111739048 B CN111739048 B CN 111739048B CN 202010728466 A CN202010728466 A CN 202010728466A CN 111739048 B CN111739048 B CN 111739048B
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郭向东
左承林
赵献礼
陈圆圆
周靓
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Low Speed Aerodynamics Institute of China Aerodynamics Research and Development Center
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Abstract

The invention is suitable for the technical field of icing wind tunnel ice shape measurement, and provides a method for digitizing an ice shape geometric contour line in an icing wind tunnel test, which comprises the steps of completing ice shape drawing by utilizing standardized ice shape drawing paper, scanning the standardized ice shape drawing paper after completing ice shape drawing, outputting a scanning picture, identifying an ice shape coordinate system and a scale line in the scanning picture, and extracting digitized discrete points of the ice shape geometric contour line in the scanning picture; the method can accurately identify the ice-shaped coordinate system and the scale line in the scanned picture without manually setting the ice-shaped coordinate system, realizes automatic extraction of the ice-shaped geometric contour line, has high extraction efficiency and high extraction precision, and is particularly suitable for large-scale test ice-shaped geometric contour line digital extraction tasks.

Description

Icing wind tunnel test ice-shaped geometric contour line digitalization method
Technical Field
The invention belongs to the technical field of icing wind tunnel ice shape measurement, and particularly relates to a method for digitizing an icing wind tunnel test ice shape geometric contour line.
Background
When an airplane flies in a cloud layer, supercooled water drops (namely liquid water drops with the temperature lower than the freezing point) in the cloud layer continuously impact the windward side of the airplane, so that the icing phenomenon of the surface of the airplane is caused. Aircraft icing is widespread in flight practice and poses a serious threat to flight safety. The icing wind tunnel is an important ground test device for developing airplane icing research and verifying an airplane component ice prevention and removal system, and plays an important role in airplane icing airworthiness examination. In an icing wind tunnel test, the geometric outline of the icing appearance is the most important icing test result and is a key parameter of test targets such as critical ice shape selection, performance evaluation of an anti-icing and deicing system, ice mold development and the like.
Icing wind tunnels generally adopt an ice shape drawing technology to realize measurement of an ice accretion two-dimensional geometric profile. The technology utilizes a hot knife to cut an ice accumulation main body, and uses a pencil to draw a two-dimensional ice-shaped contour at an ice accumulation cutting seam on the grid paper, so as to obtain the grid paper with a two-dimensional ice-shaped geometric contour line. In order to calculate the ice-shaped characteristic parameters corresponding to the ice-shaped geometric contour line on the mesh paper, it is necessary to extract the digitized discrete points of the ice-shaped geometric contour line.
Currently, commercial image digitizing software (e.g., GetData Graph digital) is commonly used in the art to manually establish a coordinate system within a picture and then take ice-shaped discrete points point-by-point along the ice-shaped geometric contour. Although the ice-shaped curve digitization is realized, the whole digitization process needs manual operation, and the discrete point data result is obviously affected by human subjective factors, so the method has the problems of low digitization efficiency, low extraction speed and low data result precision, and particularly for a large number of ice-shaped test results, the method has low processing efficiency and cannot meet the requirement of a test period.
The simplified method of ice-shape as described in patent CN105869212B also appears in the prior art, but it still does not enable automatic extraction of the geometric outline of ice-shape.
Aiming at the problem of digitalization of the ice-shaped geometric contour line in the icing wind tunnel test, related researches are few; in recent years, with the establishment of a large-scale icing wind tunnel-3 m × 2 m icing wind tunnel, under the traction of urgent requirements of an icing test, some scholars conduct preliminary research on ice shape similarity and simplification problems and develop simplified quantitative evaluation methods, but research is not conducted on the digitization problem of ice shape geometric contour lines, only commercial software is adopted for simple processing, the processing efficiency is low, the data accuracy is difficult to guarantee, the processing efficiency of icing wind tunnel ice shape test results is obviously limited, and the processing requirements of a large amount of ice shape data of the icing test are difficult to meet.
In conclusion, aiming at the problem of digitalization of the ice-shaped geometric contour line in the icing wind tunnel test, an automatic, efficient and high-precision digitalization method of the ice angle geometric contour line is not formed.
Disclosure of Invention
The invention aims to provide a method for digitizing an ice-shaped geometric contour line in an icing wind tunnel test, and aims to solve the technical problem that the ice-shaped geometric contour line cannot be automatically extracted in the prior art.
The invention provides a method for digitizing an ice-shaped geometric contour line in an icing wind tunnel test, which comprises the following steps of:
step S10: completing ice shape drawing by using standard ice shape drawing paper, and forming an ice shape geometric contour line on the standard ice shape drawing paper, wherein the ice shape geometric contour line has a fourth color; the normalized ice-shaped drawing paper comprises an ice-shaped coordinate system and a scale line, wherein the ice-shaped coordinate system takes a leading edge point of a measured airfoil as a coordinate origin, the ice-shaped coordinate system takes a chord line of the measured airfoil as an X axis, the X axis points to the tail of the measured airfoil, a Y axis of the ice-shaped coordinate system passes through the coordinate origin and is vertical to the X axis, and the Y axis points to the upper airfoil surface of the measured airfoil from the lower airfoil surface of the measured airfoil;
step S20: scanning standard ice-melting drawing paper which is subjected to ice-melting drawing, and outputting a scanning picture, wherein the scanning picture comprises an ice-melting coordinate system, a scale line and an ice-melting geometric contour line;
step S30: identifying the ice-shaped coordinate system and the scale line in the scanned picture to obtain the length L of the scale linescaleCorresponding number of pixels PscalePixel ordinate N corresponding to the origin of coordinates of an ice-shaped coordinate system0Pixel abscissa M corresponding to origin of coordinates of ice-shaped coordinate system0；
Step S40: and extracting the digitalized discrete points of the ice-shaped geometric contour line in the scanned picture.
Further, the scale line has a first color, the X-axis has a second color, and the Y-axis has a third color.
Further, the scale line is parallel to the X-axis or the Y-axis.
The invention also provides a method for digitizing the ice-shaped geometric contour line in the icing wind tunnel test, which comprises the following steps:
step S10: completing ice shape drawing by using the standard ice shape drawing paper, and forming an ice shape geometric contour line on the standard ice shape drawing paper, wherein the ice shape geometric contour line has a fourth color;
step S20: scanning standard ice-melting drawing paper which is subjected to ice-melting drawing, and outputting a scanning picture, wherein the scanning picture comprises an ice-melting coordinate system, a scale line and an ice-melting geometric contour line;
step S30: identifying the ice-shaped coordinate system and the scale line in the scanned picture to obtain the length L of the scale linescaleCorresponding number of pixels PscalePixel ordinate N corresponding to the origin of coordinates of an ice-shaped coordinate system0Pixel abscissa M corresponding to origin of coordinates of ice-shaped coordinate system0；
Step S40: and extracting the digitalized discrete points of the ice-shaped geometric contour line in the scanned picture.
Further, the step S30 includes the following steps:
step S31, defining a pixel coordinate system of the scanned picture, wherein the origin of coordinates of the pixel coordinate system is positioned at the upper left corner of the scanned picture, the horizontal axis coordinates of the pixel coordinate system correspond to the pixel point column number M of the scanned picture, and the horizontal axis coordinates of the pixel coordinate system point to the maximum column number from the minimum column number; the vertical axis coordinate of the pixel coordinate system passes through the coordinate origin of the pixel coordinate system and is vertical to the horizontal axis coordinate of the pixel coordinate system, the vertical axis coordinate of the pixel coordinate system corresponds to the pixel point row number N of the scanned picture, and the vertical axis coordinate of the pixel coordinate system points to the maximum row number from the minimum row number;
step S32, identifying the scale line in the scanned picture, extracting the pixel coordinate of the scale line, and calculating the length L of the scale linescaleCorresponding number of pixels Pscale。
Further, the step S32 includes the following steps:
step S321: traversing each pixel point in the scanned picture, extracting the pixel point coordinate of the first color, and obtaining the scale linePixel abscissa MRAnd the pixel ordinate N of the scale lineRThe method for identifying the pixel points of the first color comprises the following steps:
if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a first color:
Figure 195830DEST_PATH_IMAGE001
wherein,
Figure 375138DEST_PATH_IMAGE002
is a threshold value of the gray scale of the pixel,IM R (M i ,N i )、IM G (M i ,N i )andIM B (M i ,N i )are respectively pixel pointsP i Pixel gray values corresponding to the first color, the second color and the third color;
step S322: pixel abscissa M according to scale lineRAnd the pixel ordinate N of the scale lineRCalculating the number P of pixels of the scale line scale ：
Figure 650262DEST_PATH_IMAGE003
Wherein,Num R the total number of the first color pixels is,Num M , max andNum M,min respectively the maximum pixel abscissa and the minimum pixel abscissa of the scale lineThe corresponding number of the array is the serial number,Num N , max andNum N,min array serial numbers corresponding to the maximum pixel ordinate and the minimum pixel ordinate of the scale line respectively,jand the pixel point serial number of the scale line.
Further, the step S30 further includes the following steps:
step S33, rotating the scanned picture by an angle using the pixel coordinates of the scale line extracted in step S32θThe X axis of the ice-shaped coordinate system in the scanned picture after rotation is parallel to the horizontal axis coordinate of the picture pixel coordinate system and has the same direction, and the Y axis of the ice-shaped coordinate system is parallel to the vertical axis coordinate of the picture pixel coordinate system and has the opposite direction;
the step S33 includes the steps of:
step S331: aiming at all pixel coordinate points of the scale line, a least square method is adopted to obtain the pixel ordinate of the scale lineN R Pixel abscissa with scale lineM R Linear fit relationship between:
N R =A R M R +B R
wherein,A R andB R respectively the slope and intercept of the linear fitting equation of the proportional scale line pixel;
step S332: calculating an angleθThe calculation formula is as follows:
Figure 231416DEST_PATH_IMAGE004
Figure 566582DEST_PATH_IMAGE005
Figure 233187DEST_PATH_IMAGE006
wherein,M R,C andN R,C respectively are the average value of the abscissa of the pixel point of the scale line and the ordinate of the pixel point of the scale line,M A andN A the maximum pixel column number and the maximum pixel row number of the image are respectively.
Further, the step S30 further includes the following steps:
step S34, recognizing the X axis of the ice coordinate system in the scanned picture, extracting the pixel coordinate of the X axis, and calculating the pixel ordinate N corresponding to the coordinate origin of the ice coordinate system0；
The step S34 includes the steps of:
step S341: traversing and scanning each pixel point of the picture, extracting the pixel point coordinate of the second color, and obtaining the pixel abscissa M of the X axisBAnd pixel ordinate N of the X axisB(ii) a The identification method of the pixel points of the second color comprises the following steps: if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a second color:
Figure 312001DEST_PATH_IMAGE007
wherein,
Figure 809979DEST_PATH_IMAGE002
is a threshold value of the gray scale of the pixel,IM R (M i ,N i )、IM G (M i ,N i )andIM B (M i ,N i )is distinguished as a pixel pointP i Pixel gray values corresponding to the first color, the second color and the third color;
step S342: calculating the pixel ordinate N of the X axisBAverage value of (1), pixel ordinate N of the X axisBThe average value of the three-dimensional coordinate system is the pixel ordinate N corresponding to the coordinate origin of the ice-shaped coordinate system0Expressed as:
N 0 =average(N B )。
further, the step S30 further includes the following steps:
step S35 of recognizing an ice coordinate system within a scanned pictureYAxis, extractionYThe pixel coordinate of the axis, and the pixel ordinate corresponding to the coordinate origin of the ice-shaped coordinate systemM 0 ；
The step S35 includes the steps of:
step S351: traversing each pixel point of the picture, extracting the pixel point coordinate of the third color, and obtainingYPixel abscissa of axisM G AndYpixel ordinate of axisN G (ii) a The identification method of the pixel point of the third color comprises the following steps: if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a third color:
Figure 519309DEST_PATH_IMAGE008
wherein,
Figure 469947DEST_PATH_IMAGE002
as a pixel grey scale threshold，IM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )are respectively pixel pointsP i Pixel gray values corresponding to the first color, the second color and the third color;
step S352: computingYPixel abscissa of axisM G Is determined by the average value of (a) of (b),Ypixel abscissa of axisM G The average value of the three-dimensional coordinate system is the pixel abscissa corresponding to the coordinate origin of the ice-shaped coordinate systemM 0 Expressed as:
M 0 =average(M G )。
further, the step S40 further includes the following steps:
step S41, identifying the ice-shaped geometric contour line of the ice-shaped coordinate system in the scanned picture, extracting the pixel coordinates of the ice-shaped geometric contour line:
traversing each pixel point of the picture, extracting the coordinates of the pixel point of the fourth color, and obtaining the pixel abscissa of the ice-shaped geometric contour lineM IS And the pixel ordinate of the ice-shaped geometric contourN IS (ii) a The fourth color pixel point identification method comprises the following steps: if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a fourth color:
Figure 290136DEST_PATH_IMAGE009
wherein,
Figure 642620DEST_PATH_IMAGE010
is a threshold value of the gray level difference of the pixel,IM R (M i ,N i )、IM G (M i ,N i )andIM B (M i ,N i )are respectively pixel pointsP i Pixel gray values corresponding to the first color, the second color and the third color;
step S42, according to the pixel abscissa of the ice-shaped geometric contour lineM IS And the pixel ordinate of the ice-shaped geometric contourN IS Calculating the abscissa of the ice-shaped coordinate system of the ice-shaped geometric contour lineX IS And the abscissa of the ice-shaped coordinate system of the ice-shaped geometric contour lineY IS The calculation formula is:
Figure 585168DEST_PATH_IMAGE011
in the formula,M IS,k andN IS,k are respectively the firstkThe pixel abscissa and the pixel ordinate corresponding to the discrete points of the ice-shaped geometric contour line,X IS,k andX IS,k are respectively the firstkThe abscissa of the ice-shaped coordinate system and the ordinate of the ice-shaped coordinate system corresponding to the discrete points of the ice-shaped geometric contour line,kdiscrete point numbers are shown on the geometric outline of the ice shape.
Further, the first color is red, the second color is green, the third color is blue, and the fourth color is gray.
Compared with the prior art, the invention has the technical effects that:
1. in the invention, before ice shape measurement is carried out, the position relation between the standard ice shape drawing paper and the wing to be measured is determined, and in the prior art, a coordinate system is usually added manually after the ice shape measurement, so that the manual error generated when the coordinate system is added manually in the prior art can be avoided;
2. in the invention, before ice shape measurement, corresponding standard ice shape drawing paper can be manufactured in batches, and compared with the prior art, the time for manually adding a coordinate system can be saved;
3. according to the icing wind tunnel test ice-shaped geometric contour line digitalization method, the pixel point coordinates of the ice-shaped geometric contour line in the scanned picture can be extracted and converted into the ice-shaped coordinate system coordinates, and ice-shaped discrete points need to be taken point by point in the prior art, so that the extraction efficiency and the accuracy are high;
4. the icing wind tunnel test ice-shaped geometric contour line digitalization method can accurately identify an ice-shaped coordinate system and a scale line in a scanned picture without manually setting the ice-shaped coordinate system, can extract discrete points of the ice-shaped geometric contour line, realizes automatic extraction of the ice-shaped geometric contour line, has high extraction efficiency and high extraction precision, and is particularly suitable for large-scale test ice-shaped geometric contour line digitalization extraction tasks.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention or in the description of the prior art will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a standardized ice-shaped drawing sheet provided by an embodiment of the present invention;
FIG. 2 is a schematic view of a normalized ice-formed drawing sheet having a notch according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart of a method for digitizing an ice geometric contour line in an icing wind tunnel test according to an embodiment of the present invention;
FIG. 4 is a schematic view of a scanned picture provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a pixel coordinate system definition of a scanned picture according to an embodiment of the present invention;
FIG. 6 is a schematic view of a rotated scanned picture according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a digitized geometric outline of an ice shape according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.
As shown in fig. 3, an embodiment of the present invention provides a method for digitizing an ice geometric contour line in an icing wind tunnel test, which includes the following steps:
step S10: completing ice shape drawing by using standard ice shape drawing paper, and forming an ice shape geometric contour line on the standard ice shape drawing paper, wherein the ice shape geometric contour line has a fourth color;
step S20: scanning the standardized ice-shaped drawing paper which is subjected to ice-shaped drawing, and outputting a scanned picture, wherein the scanned picture comprises an ice-shaped coordinate system, a scale line and an ice-shaped geometric contour line 3, as shown in fig. 4, it is worth explaining that 3 in fig. 4 is only a reference numeral in a patent application document, and on an actual scanned picture, for convenience of identification, no reference numeral exists.
Step S30: identifying the ice-shaped coordinate system and the scale line in the scanned picture to obtain the length L of the scale linescaleCorresponding number of pixels PscalePixel ordinate N corresponding to the origin of coordinates of an ice-shaped coordinate system0Pixel abscissa M corresponding to origin of coordinates of ice-shaped coordinate system0；
Step S40: and extracting the digitalized discrete points of the ice-shaped geometric contour line in the scanned picture.
The standard ice-melting drawing paper in the embodiment of the invention is shown in figure 1 and comprises an ice-melting coordinate system and a scale line 1; the ice-shaped coordinate system comprises an X axis and a Y axis;
before ice shape measurement is carried out, a notch 2 shown in figure 2 needs to be cut out from standard ice shape drawing paper, the shape of the notch 2 is the same as the airfoil shape of the wing to be measured, and a machine to be measured is accommodated in the notch 2 when ice shape measurement is carried out;
in order to make the wing to be measured have a uniquely defined positional relationship with the ice coordinate system and the scale line 1:
the ice-shaped coordinate system takes a leading edge point of the measured airfoil profile as a coordinate origin O;
the ice-shaped coordinate system takes a chord line of the measuring airfoil as an X axis, and the X axis points to the tail of the measuring airfoil;
the Y axis of the ice-shaped coordinate system passes through the coordinate origin and is perpendicular to the X axis, and the Y axis points to the upper wing surface of the measuring wing profile from the lower wing surface of the measuring wing profile;
therefore, in the icing wind tunnel test ice-shaped geometric contour line digitalization method, the position relation between the standard ice-shaped drawing paper and the wing to be measured is determined before ice-shaped measurement is carried out, and in the prior art, a coordinate system is usually added manually after the ice-shaped measurement, so that the embodiment of the invention can avoid manual errors generated when the coordinate system is added manually in the prior art; in addition, in the embodiment of the invention, before ice shape measurement is carried out, corresponding standard ice shape drawing paper can be manufactured in batches, and compared with the prior art, the time for manually adding a coordinate system can be saved.
It should be noted that 1, X, Y, O, 2 in fig. 1 and 2 are only reference numerals in the patent application document, and no reference numerals are provided on the actual standardized ice-shaped drawing paper for the convenience of identification.
To facilitate subsequent picture processing, the scale line has a first color, the X-axis has a second color, and the Y-axis has a third color.
As shown in fig. 1 and 2, the scale line 1 is located in the second quadrant, and those skilled in the art will appreciate that the scale line 1 may also be located in other quadrants, and the present invention is not limited to the location of the scale line 1.
The scale line 1 has an actual physical length Lscale，LscaleAs an image scale length for subsequent conversion of pixel coordinates to actual physical coordinates, the details of which are described below.
The scale line 1 is parallel to either the X-axis or the Y-axis, which is convenient for ease of identification to facilitate conversion.
It should be noted that the scale line 1 in the drawings is parallel to the X-axis, and those skilled in the art will understand that the scale line 1 may also be parallel to the Y-axis, and the invention is not limited thereto.
In addition, the lowest part of the normalized ice-shaped drawing paper can be provided with a test information table, the content of the test information table comprises a test name, a test number, test time, an ice-shaped position, test conditions and test phenomena, and for the convenience of distinguishing from an ice-shaped coordinate system, a scale line and an ice-shaped geometric contour line, the form line is represented by a black dotted line, and characters in the form are set to be black.
Further, the step S30 includes the following steps:
step S31, as shown in FIG. 5, defining a pixel coordinate system of the scanned picture, wherein the origin of coordinates of the pixel coordinate system is located at the upper left corner of the scanned picture, the horizontal axis coordinates of the pixel coordinate system correspond to the pixel point column number M of the scanned picture, and the horizontal axis coordinates of the pixel coordinate system point to the maximum column number from the minimum column number; the vertical axis coordinate of the pixel coordinate system passes through the coordinate origin of the pixel coordinate system and is vertical to the horizontal axis coordinate of the pixel coordinate system, the vertical axis coordinate of the pixel coordinate system corresponds to the pixel point row number N of the scanned picture, and the vertical axis coordinate of the pixel coordinate system points to the maximum row number from the minimum row number; by pixel pointsP i For example, its pixel coordinate is (M)i，Ni）
Step S32, identifying the scale line in the scanned pictureExtracting the pixel coordinates of the proportional scale line and calculating the length L of the proportional scale linescaleCorresponding number of pixels Pscale。
Further, the step S32 includes the following steps:
step S321: traversing each pixel point in the scanned picture, extracting the pixel point coordinate of the first color, and obtaining the pixel abscissa M of the scale lineRAnd the pixel ordinate N of the scale lineRThe method for identifying the pixel points of the first color comprises the following steps:
if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a first color:
Figure 960786DEST_PATH_IMAGE012
wherein,
Figure 381403DEST_PATH_IMAGE002
is a threshold value of the gray scale of the pixel,IM R (M i ,N i )、IM G (M i ,N i )andIM B (M i ,N i )are respectively pixel pointsP i Corresponding to the pixel gray values of the first color, the second color and the third color.
Step S322: pixel abscissa M according to scale lineRAnd the pixel ordinate N of the scale lineRCalculating the number P of pixels of the scale line scale ：
Figure 853972DEST_PATH_IMAGE013
Wherein,Num R the total number of the first color pixels is,Num M , max andNum M,min array serial numbers corresponding to the maximum pixel abscissa and the minimum pixel abscissa of the scale line respectively,Num N , max andNum N,min array serial numbers corresponding to the maximum pixel ordinate and the minimum pixel ordinate of the scale line respectively,jand the pixel point serial number of the scale line.
Since the scanned picture tends to have a certain rotation, as shown in the scanned picture in fig. 4, it is obvious that there is a certain rotation angle, so as to facilitate the coordinate transformation between the ice coordinate system and the pixel coordinate system, in step S30, the method further includes the following steps:
step S33, rotating the scanned picture by an angle using the pixel coordinates of the scale line extracted in step S32θThe X axis of the ice coordinate system in the rotated scanned picture is parallel to the horizontal axis coordinate of the picture pixel coordinate system and has the same direction, the Y axis of the ice coordinate system is parallel to the vertical axis coordinate of the picture pixel coordinate system and has the opposite direction, and the rotated scanned picture is as shown in fig. 6;
specifically, the step S33 includes the steps of:
step S331: aiming at all pixel coordinate points of the scale line, a least square method is adopted to obtain the pixel ordinate of the scale lineN R Pixel abscissa with scale lineM R Linear fit relationship between:
N R =A R M R +B R
wherein,A R andB R respectively the slope and intercept of the linear fitting equation of the proportional scale line pixel;
step S332: calculating an angleθThe calculation formula is as follows:
Figure 905105DEST_PATH_IMAGE014
Figure 830336DEST_PATH_IMAGE015
Figure 989397DEST_PATH_IMAGE016
wherein,M R,C andN R,C respectively are the average value of the abscissa of the pixel point of the scale line and the ordinate of the pixel point of the scale line,M A andN A the maximum pixel column number and the maximum pixel row number of the image are respectively.
Further, the step S30 further includes the following steps:
step S34, recognizing the X axis of the ice coordinate system in the scanned picture, extracting the pixel coordinate of the X axis, and calculating the pixel ordinate N corresponding to the coordinate origin of the ice coordinate system0；
The step S34 includes the steps of:
step S341: traversing and scanning each pixel point of the picture, extracting the pixel point coordinate of the second color, and obtaining the pixel abscissa M of the X axisBAnd pixel ordinate N of the X axisB(ii) a The identification method of the pixel points of the second color comprises the following steps: if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a second color:
Figure 50894DEST_PATH_IMAGE017
wherein,
Figure 335245DEST_PATH_IMAGE002
is a threshold value of the gray scale of the pixel,IM R (M i ,N i )、IM G (M i ,N i )andIM B (M i ,N i )are respectively pixel pointsP i Pixel gray values corresponding to the first color, the second color and the third color;
step S342: calculating the pixel ordinate N of the X axisBAverage value of (1), pixel ordinate N of the X axisBThe average value of the three-dimensional coordinate system is the pixel ordinate N corresponding to the coordinate origin of the ice-shaped coordinate system0Expressed as:
N 0 =average(N B )。
further, the step S30 further includes the following steps:
step S35 of recognizing an ice coordinate system within a scanned pictureYAxis, extractionYThe pixel coordinate of the axis, and the pixel ordinate corresponding to the coordinate origin of the ice-shaped coordinate systemM 0 ；
The step S35 includes the steps of:
step S351: traversing each pixel point of the picture, extracting the pixel point coordinate of the third color, and obtainingYPixel abscissa of axisM G AndYpixel ordinate of axisN G (ii) a The identification method of the pixel point of the third color comprises the following steps: if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a third color:
Figure 685455DEST_PATH_IMAGE018
wherein,
Figure 713454DEST_PATH_IMAGE002
is a threshold value of the gray scale of the pixel,IM R (M i ,N i )、IM G (M i ,N i )andIM B (M i ,N i )are respectively pixel pointsP i Pixel gray values corresponding to the first color, the second color and the third color;
step S352: computingYPixel abscissa of axisM G Is determined by the average value of (a) of (b),Ypixel abscissa of axisM G The average value of the three-dimensional coordinate system is the pixel abscissa corresponding to the coordinate origin of the ice-shaped coordinate systemM 0 Expressed as:
M 0 =average(M G )。
further, the step S40 further includes the following steps:
step S41, identifying the ice-shaped geometric contour line of the ice-shaped coordinate system in the scanned picture, extracting the pixel coordinates of the ice-shaped geometric contour line:
traversing each pixel point of the picture, extracting the coordinates of the pixel point of the fourth color, and obtaining the pixel abscissa of the ice-shaped geometric contour lineM IS And the pixel ordinate of the ice-shaped geometric contourN IS (ii) a The fourth color pixel point identification method comprises the following steps:if a pixel pointP i Corresponding toIM R (M i ,N i )、IM G (M i ,N i )AndIM B (M i ,N i )if the three gray values satisfy the following relationship, the pixel point is judgedP i Pixel points of a fourth color:
Figure 832719DEST_PATH_IMAGE019
wherein,
Figure 22392DEST_PATH_IMAGE010
is a threshold value of the gray level difference of the pixel,IM R (M i ,N i )、IM G (M i ,N i )andIM B (M i ,N i )are respectively pixel pointsP i Pixel gray values corresponding to the first color, the second color and the third color;
step S42, according to the pixel abscissa of the ice-shaped geometric contour lineM IS And the pixel ordinate of the ice-shaped geometric contourN IS Calculating the abscissa of the ice-shaped coordinate system of the ice-shaped geometric contour lineX IS And the abscissa of the ice-shaped coordinate system of the ice-shaped geometric contour lineY IS The calculation formula is:
Figure 859898DEST_PATH_IMAGE011
in the formula,M IS,k andN IS,k are respectively the firstkThe pixel abscissa and the pixel ordinate corresponding to the discrete points of the ice-shaped geometric contour line,X IS,k andX IS,k are respectively the firstkThe abscissa of the ice-shaped coordinate system and the ordinate of the ice-shaped coordinate system corresponding to the discrete points of the ice-shaped geometric contour line,kdiscrete point numbers are shown on the geometric outline of the ice shape.
Fig. 7 is a schematic diagram of a digitized ice-shaped geometric contour line, which is composed of discrete points of the ice-shaped geometric contour line.
Further, for convenience of identification, the first color is red, the second color is green, the third color is blue, and the fourth color is gray.
By the icing wind tunnel test ice-shaped geometric contour line digitalization method in the second embodiment of the invention, an ice-shaped coordinate system and a scale line in a scanned picture can be accurately identified, and ice-shaped geometric contour line discrete points are extracted, so that automatic extraction of the ice-shaped geometric contour line can be realized, the extraction efficiency is high, the extraction precision is high, the problem of digitalization of the ice-shaped geometric contour line in the icing wind tunnel test can be effectively solved, and technical support is provided for test targets of critical ice shape selection, ice prevention and removal system performance evaluation, ice mold development and the like.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (8)

1. A method for digitizing an ice-shaped geometric contour line in an icing wind tunnel test is characterized by comprising the following steps of:
step S10: completing ice shape drawing by using standard ice shape drawing paper, and forming an ice shape geometric contour line on the standard ice shape drawing paper, wherein the ice shape geometric contour line has a fourth color; the normalized ice-shaped drawing paper comprises an ice-shaped coordinate system and a scale line, wherein the ice-shaped coordinate system takes a leading edge point of a measured airfoil as a coordinate origin, the ice-shaped coordinate system takes a chord line of the measured airfoil as an X axis, the X axis points to the tail of the measured airfoil, a Y axis of the ice-shaped coordinate system passes through the coordinate origin and is vertical to the X axis, and the Y axis points to the upper airfoil surface of the measured airfoil from the lower airfoil surface of the measured airfoil;
step S20: scanning standard ice-melting drawing paper which is subjected to ice-melting drawing, and outputting a scanning picture, wherein the scanning picture comprises an ice-melting coordinate system, a scale line and an ice-melting geometric contour line;
step S30: identifying the ice-shaped coordinate system and the scale line in the scanned picture to obtain the length L of the scale linescaleCorresponding number of pixels PscalePixel ordinate N corresponding to the origin of coordinates of an ice-shaped coordinate system0Pixel abscissa M corresponding to origin of coordinates of ice-shaped coordinate system0；
Step S40: extracting ice-shaped geometric contour line digitalized discrete points in the scanned picture;
wherein, in step S30, the method includes the following steps:
step S31, defining a pixel coordinate system of the scanned picture, wherein the origin of coordinates of the pixel coordinate system is positioned at the upper left corner of the scanned picture, the horizontal axis coordinates of the pixel coordinate system correspond to the pixel point column number M of the scanned picture, and the horizontal axis coordinates of the pixel coordinate system point to the maximum column number from the minimum column number; the vertical axis coordinate of the pixel coordinate system passes through the coordinate origin of the pixel coordinate system and is vertical to the horizontal axis coordinate of the pixel coordinate system, the vertical axis coordinate of the pixel coordinate system corresponds to the pixel point row number N of the scanned picture, and the vertical axis coordinate of the pixel coordinate system points to the maximum row number from the minimum row number;
step S32, identifying the scale line in the scanned picture, extracting the pixel coordinate of the scale line, and calculating the length L of the scale linescaleCorresponding number of pixels Pscale；
The step S32 includes the steps of:
step S321: traversing each pixel point in the scanned picture, extracting the pixel point coordinate of the first color, and obtaining the pixel abscissa M of the scale lineRAnd the pixel ordinate N of the scale lineRThe method for identifying the pixel points of the first color comprises the following steps:
if pixel point PiCorresponding IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) If the three gray values satisfy the following relationship, the pixel point P is judgediPixel points of a first color:
IMR(Mi,Ni)-IMG(Mi,Ni)>gray and IMR(Mi,Ni)-IMB(Mi,Ni)>gray
wherein,grayfor pixel grey scale threshold, IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) Are respectively pixel points PiPixel gray values corresponding to the first color, the second color and the third color;
step S322: pixel abscissa M according to scale lineRAnd the pixel ordinate N of the scale lineRCalculating the number P of pixels of the scale linescale：
Figure FDA0002728284600000021
Figure FDA0002728284600000022
Figure FDA0002728284600000023
Wherein, NumRIs the total number of the first color pixel points, NumM,maxAnd NumM,minArray serial numbers, Num, corresponding to the maximum pixel abscissa and the minimum pixel abscissa of the scale line respectivelyN,maxAnd NumN,minThe serial numbers of the array corresponding to the maximum pixel ordinate and the minimum pixel ordinate of the scale line respectively, and j is the serial number of the pixel point of the scale line.
2. The method of claim 1, wherein the scale line has a first color, the X-axis has a second color, and the Y-axis has a third color.
3. The method for digitizing an ice-shaped geometric contour line for an icing wind tunnel test according to claim 1, wherein the scale line is parallel to an X-axis or a Y-axis.
4. The method for digitizing an ice geometric contour line in an icing wind tunnel test according to claim 1, wherein the step S30 further comprises the steps of:
step S33, rotating the scanned picture by an angle theta by using the pixel coordinates of the scale line extracted in the step S32, wherein the X axis of the ice-shaped coordinate system in the scanned picture after rotation is parallel to the horizontal axis coordinate of the picture pixel coordinate system and has the same direction, and the Y axis of the ice-shaped coordinate system is parallel to the vertical axis coordinate of the picture pixel coordinate system but has the opposite direction;
the step S33 includes the steps of:
step S331: aiming at all pixel coordinate points of the scale line, a least square method is adopted to obtain a pixel ordinate N of the scale lineRPixel abscissa M of scale lineRLinear fit relationship between:
NR＝ARMR+BR
wherein A isRAnd BRRespectively the slope and intercept of the linear fitting equation of the proportional scale line pixel;
step S332: calculating the angle theta, and the calculation formula is as follows:
Figure FDA0002728284600000031
NR,C＝average(NR),MR,C＝average(MR)
wherein M isR,CAnd NR,CRespectively being scale line pixel pointsAverage of the abscissa, the ordinate of the scale line pixel points, MAAnd NAThe maximum pixel column number and the maximum pixel row number of the image are respectively.
5. The method for digitizing an ice geometric contour line in an icing wind tunnel test according to claim 1, wherein the step S30 further comprises the steps of:
step S34, recognizing the X axis of the ice coordinate system in the scanned picture, extracting the pixel coordinate of the X axis, and calculating the pixel ordinate N corresponding to the coordinate origin of the ice coordinate system0；
The step S34 includes the steps of:
step S341: traversing and scanning each pixel point of the picture, extracting the pixel point coordinate of the second color, and obtaining the pixel abscissa M of the X axisBAnd pixel ordinate N of the X axisB(ii) a The identification method of the pixel points of the second color comprises the following steps: if pixel point PiCorresponding IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) If the three gray values satisfy the following relationship, the pixel point P is judgediPixel points of a second color:
IMB(Mi,Ni)-IMR(Mi,Ni)>gray and IMB(Mi,Ni)-IMG(Mi,Ni)>gray
wherein,grayfor pixel grey scale threshold, IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) Are respectively pixel points PiPixel gray values corresponding to the first color, the second color and the third color;
step S342: calculating the pixel ordinate N of the X axisBAverage value of (1), pixel ordinate N of the X axisBThe average value of the three-dimensional coordinate system is the pixel ordinate N corresponding to the coordinate origin of the ice-shaped coordinate system0Expressed as:
N0＝average(NB)。
6. the method for digitizing an ice geometric contour line in an icing wind tunnel test according to claim 1, wherein the step S30 further comprises the steps of:
step S35, recognizing the Y axis of the ice coordinate system in the scanned picture, extracting the pixel coordinate of the Y axis, and calculating the pixel ordinate M corresponding to the coordinate origin of the ice coordinate system0；
The step S35 includes the steps of:
step S351: traversing each pixel point of the picture, extracting the coordinates of the pixel point of the third color, and obtaining the pixel abscissa M of the Y axisGAnd pixel ordinate N of the Y axisG(ii) a The identification method of the pixel point of the third color comprises the following steps: if pixel point PiCorresponding IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) If the three gray values satisfy the following relationship, the pixel point P is judgediPixel points of a third color:
IMG(Mi,Ni)-IMR(Mi,Ni)>gray and IMG(Mi,Ni)-IMB(Mi,Ni)>gray
wherein,grayfor pixel grey scale threshold, IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) Are respectively pixel points PiPixel gray values corresponding to the first color, the second color and the third color;
step S352: calculating the pixel abscissa M of the Y-axisGAverage value of (3), pixel abscissa M of Y axisGThe average value of the three-dimensional coordinate system is the pixel abscissa M corresponding to the coordinate origin of the ice-shaped coordinate system0Expressed as:
M0＝average(MG)。
7. the method for digitizing an ice geometric contour line in an icing wind tunnel test according to claim 1, wherein the step S40 further comprises the steps of:
step S41, identifying the ice-shaped geometric contour line of the ice-shaped coordinate system in the scanned picture, extracting the pixel coordinates of the ice-shaped geometric contour line:
traversing each pixel point of the picture, extracting the coordinates of the pixel point of the fourth color, and obtaining the pixel abscissa M of the ice-shaped geometric contour lineISAnd the pixel ordinate N of the geometric outline of iceIS(ii) a The fourth color pixel point identification method comprises the following steps: if pixel point PiCorresponding IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) If the three gray values satisfy the following relationship, the pixel point P is judgediPixel points of a fourth color:
|IMG(Mi,Ni)-IMR(Mi,Ni)|<Δgray
and|IMG(Mi,Ni)-IMB(Mi,Ni)|<Δgray
and|IMB(Mi,Ni)-IMR(Mi,Ni)|<Δgray
wherein,grayfor pixel grey scale threshold, IMR(Mi,Ni)、IMG(Mi,Ni) And IMB(Mi,Ni) Are respectively pixel points PiPixel gray values corresponding to the first color, the second color and the third color;
step S42, according to the pixel abscissa M of the ice-shaped geometric contour lineISAnd the pixel ordinate N of the geometric outline of iceISCalculating the abscissa X of the ice-shaped coordinate system of the ice-shaped geometric contour lineISAnd the abscissa Y of the ice-shaped coordinate system of the ice-shaped geometric contour lineISThe calculation formula is:
Figure FDA0002728284600000061
Figure FDA0002728284600000062
in the formula, MIS,kAnd NIS,kRespectively corresponding to the k-th ice-shaped geometric contour line discrete point, a pixel abscissa, a pixel ordinate and an XIS,kAnd XIS,kRespectively the abscissa of the ice-shaped coordinate system and the ordinate of the ice-shaped coordinate system corresponding to the k-th discrete point of the ice-shaped geometric contour line, and k is the serial number of the discrete point of the ice-shaped geometric contour line.
8. The method according to claim 2, wherein the first color is red, the second color is green, the third color is blue, and the fourth color is gray.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104596484A (en) * 2015-01-30 2015-05-06 黄河水利委员会黄河水利科学研究院 Method of measuring drift ice density in ice flood season of Yellow River
CN109631776A (en) * 2018-12-27 2019-04-16 南京航空航天大学 A kind of high-voltage power line conductive knot ice thickness method for automatic measurement
CN110763205A (en) * 2019-11-05 2020-02-07 新疆维吾尔自治区测绘科学研究院 Method for generating orthophoto map of border narrow and long area by digital photogrammetric system

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4044826B2 (en) * 2002-07-25 2008-02-06 富士通株式会社 Semiconductor integrated circuit
CN105869212B (en) * 2016-03-11 2018-10-12 空气动力学国家重点实验室 A kind of ice shape simplification method
CN108830898A (en) * 2018-03-30 2018-11-16 北京师范大学 A kind of food volume evaluation method based on 3D model nesting
CN109544576A (en) * 2018-11-23 2019-03-29 中国空气动力研究与发展中心低速空气动力研究所 A kind of model aircraft ice shape contour extraction method based on machine vision
CN111323200B (en) * 2020-05-11 2020-08-07 中国空气动力研究与发展中心低速空气动力研究所 Icing area calculation method for icing wind tunnel test

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104596484A (en) * 2015-01-30 2015-05-06 黄河水利委员会黄河水利科学研究院 Method of measuring drift ice density in ice flood season of Yellow River
CN109631776A (en) * 2018-12-27 2019-04-16 南京航空航天大学 A kind of high-voltage power line conductive knot ice thickness method for automatic measurement
CN110763205A (en) * 2019-11-05 2020-02-07 新疆维吾尔自治区测绘科学研究院 Method for generating orthophoto map of border narrow and long area by digital photogrammetric system

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