Dynamic directionality symbol position restriction algorithm based on relative offset

Abstract

The position limiting algorithm of the dynamic directivity symbol based on relative offset of the application comprises determining the display range of the dynamic directivity symbol on the display interface, the dynamic directivity symbol comprising point type symbol and line type symbol; determining the first display position and the first relative offset of the position limited dynamic directivity point type symbol; determining the second display position and the second relative offset of the position limited dynamic directivity line type symbol; controlling the display position of the point type symbol in the picture according to the first display position and the first relative offset, and controlling the display position of the line type symbol in the picture according to the second display position and the second relative offset, effectively solving the problem that the dynamic directivity symbol cannot be observed after exceeding the display range.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aiming display technology, and relates to a position limiting algorithm for dynamic pointing symbols based on relative offset. BACKGROUND

[0002] The dynamic pointing symbols used in the aiming display system are mostly navigation, target tracking, aiming or attack symbols, the rotation angle of which is the roll angle of the carrier, and the reference symbol is a flight path marker (FPM), a climb / dive marker (CDM) or a center point of the field of view.

[0003] For the aiming display system, the field of view (FOV) is divided into two types, namely the instantaneous field of view (IFOV) and the total field of view (TFOV). The instantaneous field of view is the maximum field of view that can be observed by the user at the designed eye position without moving the head, and the total field of view is the total convergence angle of the image rays that can be observed by the eye position movement. Generally, the instantaneous field of view is smaller than the total field of view.

[0004] Different dynamic pointing symbols have different display ranges due to different symbol functions, for example, some symbols need to be displayed in the instantaneous field of view, some symbols need to be displayed in the field of view extended by 1 degree based on the instantaneous field of view, and some symbols need to be displayed in the total field of view. When the position of the dynamic pointing symbol exceeds the corresponding display range, the user will not be able to observe the dynamic pointing symbol, and thus cannot effectively guide the search, identification, tracking, aiming or attack of the airborne sensor and weapon, and therefore it is necessary to limit the position of the dynamic pointing symbol that exceeds the corresponding display range so as to be observed by the user. SUMMARY

[0005] Therefore, the position limiting algorithm for dynamic pointing symbols based on relative offset provided by the present application fully considers the position limiting requirements of point and line dynamic pointing symbols, and respectively provides corresponding position limiting algorithms, which can effectively solve the problem that the dynamic pointing symbol cannot be observed when it exceeds the display range.

[0006] A position limiting algorithm for dynamic pointing symbols based on relative offset, the position limiting algorithm comprising the following steps:

[0007] Step 1: determining the display range of the dynamic pointing symbol on the display interface, the dynamic pointing symbol including point and line symbols;

[0008] Step two: according to the feature of point symbol, the theoretical display position is calculated, when the preset angle is adopted, the first preset method and the second preset method are used for processing, when the non-preset angle is adopted, the first display position and the first relative offset of the dynamic pointing point symbol after position restriction are determined by judging the slope range of the connecting line between the reference symbol and the point symbol;

[0009] Step three: according to the feature of line symbol, the perpendicular point from the reference symbol to the line symbol is calculated, when the preset angle is adopted, the third preset method and the fourth preset method are used for processing, when the non-preset angle is adopted, the expression of four straight lines passing through the four vertices of the display range and parallel to the line symbol is determined, the second display position and the second relative offset of the dynamic pointing line symbol after position restriction are determined by judging the positive and negative of the relative offset and using the distance from the reference symbol to the four straight lines;

[0010] Step four: the display position of the point symbol in the picture is controlled according to the first display position and the first relative offset, and the display position of the line symbol in the picture is controlled according to the second display position and the second relative offset.

[0011] The technical beneficial effects of the present application are as follows:

[0012] Firstly, the definition and display range of the dynamic pointing symbol are determined, and the dynamic pointing symbol is divided into two categories, point symbol and line symbol; secondly, according to the feature of the point symbol, the theoretical display position is calculated first, then the processing when the preset angle is considered, and finally for the non-preset angle, the first display position and the first relative offset of the dynamic pointing point symbol after position restriction are determined by judging the slope range of the connecting line between the reference symbol and the point symbol; thirdly, according to the feature of the line symbol, the perpendicular point from the reference symbol to the line symbol is calculated first, then the processing when the preset angle is considered, and finally for the non-preset angle, the second display position and the second relative offset of the dynamic pointing line symbol after position restriction are determined by determining the expression of four straight lines passing through the four vertices of the display range and parallel to the line symbol, judging the positive and negative of the relative offset, and using the distance from the reference symbol to the four straight lines; finally, the display position of the point symbol in the picture is controlled according to the first display position and the first relative offset, and the display position of the line symbol in the picture is controlled according to the second display position and the second relative offset. The method fully considers the position restriction requirements of the point and line dynamic pointing symbols, respectively gives the corresponding position restriction algorithm, and can effectively solve the problem that the dynamic pointing symbol cannot be observed when it exceeds the display range. BRIEF DESCRIPTION OF DRAWINGS

[0013] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Fig. 1 A schematic diagram illustrating the positional constraints of dynamic directional symbols for point classes;

[0015] Fig. 2 A schematic diagram illustrating the limitations of a point-type dynamic directional symbol at a preset angle position;

[0016] Fig. 3 This is a schematic diagram illustrating the restrictions on the position of dynamic directional symbols for line types. Detailed Implementation

[0017] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0018] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0019] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0020] Basic concepts of dynamic directional symbols

[0021] Dynamic directional symbols refer to symbols that rotate around a reference symbol and have a certain positional offset relative to the reference symbol. Based on the different factors that need to be considered when restricting their position, dynamic directional symbols are divided into two types: point symbols and line symbols. Point symbols are those whose position restriction only requires consideration of the symbol's reference point, without needing to consider the symbol's own size; these symbols are generally small in size. Line symbols are those whose position restriction requires consideration of both the symbol's reference point and the symbol's own size; these symbols are generally larger in size and mostly linear. The display area corresponding to a dynamic directional symbol can be rectangular, circular, or other styles. This invention only uses two rectangular areas—one for azimuth (W degrees) and one for pitch (H degrees), and the other for azimuth (WB degrees) and one for pitch (HB degrees)—as examples for illustration. Furthermore, the display area of ​​a dynamic directional symbol must be greater than or equal to the display area of ​​its reference symbol.

[0022] like Figs. 1 to 3 The position restriction algorithm for dynamic directional symbols based on relative offset shown includes the following steps:

[0023] Step 1: Determine the display range of dynamic directional symbols on the display interface. Dynamic directional symbols include dot symbols and line symbols.

[0024] Step 2: Calculate the theoretical display position based on the characteristics of dot symbols. When the angle is preset (0 degrees, ±90 degrees, ±180 degrees), use the first preset method and the second preset method for processing. When the angle is not preset, determine the first display position and the first relative offset after the dynamic directional dot symbol position restriction by judging the slope range of the connecting line between the reference symbol and the dot symbol.

[0025] Step 3: Calculate the perpendicular point from the reference symbol to the line symbol based on the characteristics of the line symbol. If it is a preset angle, use the third and fourth preset methods for processing. If it is a non-preset angle, determine the expression of the four straight lines that pass through the four vertices of the display range and are parallel to the line symbol. By judging the positive or negative of the relative offset and using the distance from the reference symbol to the four straight lines, determine the second display position and the second relative offset after the dynamic directional line symbol position restriction.

[0026] Step 4: Based on the first display position and the display position of the first relative offset control point symbol in the screen, and based on the second display position and the display position of the second relative offset control line symbol in the screen, for example, draw dynamic directional line symbols in the screen using OpenGL based on the second display position and the second relative offset position, and display them, thereby guiding the airborne sensors to search, identify and track.

[0027] Considering different dynamic pointing symbols, the corresponding display ranges are different due to different symbol effects. When the position of a dynamic pointing symbol exceeds the corresponding display range, the user will not be able to observe the dynamic pointing symbol, and therefore the dynamic pointing symbol exceeding the corresponding display range needs to be position-limited. Before applying a position-limiting algorithm, it is necessary to determine which type of dynamic pointing symbol belongs to and determine the corresponding display range boundary, and then select a corresponding position-limiting algorithm according to the symbol type, and process to obtain the limited display position and the limited relative offset, so as to control the display position of the symbol in the picture.

[0028] As the specific embodiments provided in the present case, the dynamic pointing symbol is a dynamic symbol that rotates around a reference symbol and has a position offset relative to the reference symbol, and the point symbol is a symbol that only needs to consider the symbol reference point when position-limited, without considering the size of the symbol itself; such a symbol is generally small in size. The line symbol is a symbol that needs to consider the symbol reference point and the size of the symbol when position-limited. Such a symbol is generally large in size and mostly linear.

[0029] As the specific embodiments provided in the present case, the first display position and the first relative offset of the position-limited dynamic pointing point symbol are determined; the second display position and the second relative offset of the position-limited dynamic pointing line symbol are determined. Since the first relative offset and the second relative offset have pointing properties, there are positive and negative differences, and the positivity and negativity of the relative offset after position limitation are the same as the positivity and negativity of the initial state relative offset.

[0030] As the specific embodiments provided in the present case, for a non-pre-set angle, the slope range of the connecting line of the reference symbol and the point symbol is determined to include the slope of the connecting line of the point dynamic pointing symbol, the connecting line of the point dynamic pointing symbol is the line connecting the reference point of the reference symbol and the reference point of the point dynamic pointing symbol, and the slope of the connecting line of the non-pre-set angle is determined, wherein

[0031] The slope of the connecting line of the non-pre-set angle is denoted as slope FD0slope, assuming that the rotation angle of 12 o'clock is 0 degrees and increases counterclockwise, and the slope FD0slope can be obtained as

[0032] FD0slope=tan(roll+90), roll is the non-pre-set angle.

[0033] Further, when a point dynamic pointing symbol exceeds its corresponding display range, the intersection point of the connecting line of the point dynamic pointing symbol and the boundary of the corresponding display range is taken as the first display position of the position-limited point dynamic pointing symbol, and then the first relative offset is obtained, including

[0034] Determination of the first display position and the first relative offset

[0035] Reference point F of the reference symbol is obtained, and the coordinates are (fx, fy). The display range corresponding to the dynamic directivity symbol is obtained, which is a rectangular range with W degrees of azimuth direction and H degrees of pitch direction. The relative offset of the point type dynamic directivity symbol is Originalshift, and the relative offset is a non-zero value. In the following processing, it is assumed that the relative offset is positive upward and negative downward. First, the theoretical display position D0 (D0x, D0y) of the point type dynamic directivity symbol is calculated, and then it is judged whether D0 exceeds the display range. If it exceeds, the position restriction is performed on D0 to obtain the first display position D1 (D1x, D1y) of the point type symbol after the position restriction and the corresponding first relative offset Limitshift after the position restriction, wherein,

[0036] The theoretical display position D0 is calculated, D0x = fx - Originalshift*sin(roll);

[0037] D0y = fy + Originalshift*cos(roll);

[0038] It is judged whether D0 exceeds the display range. If the azimuth direction is located in the range of [-W / 2, W / 2] and the pitch direction is located in the range of [-H / 2, H / 2], it does not exceed the display range. D0 is the first display position D1 of the point type symbol, and Originalshift is the first relative offset Limitshift. Otherwise, the position restriction is performed.

[0039] Since the slope of the straight line FD0 is needed in the position restriction process, the following processing is performed for the preset angle:

[0040] When roll is ±90 degrees, the straight line FD0 is parallel to the X axis. Since the display range of the dynamic directivity symbol needs to be greater than or equal to the display range of its reference symbol, fy does not exceed the range, and then D0y also does not exceed the range. Therefore, D0x exceeds the range. The first preset method (according to the following three formulas) is used to calculate the first display position D1 after the position restriction and the first relative offset Limitshift, wherein sign(X) is -1 when X is negative, and otherwise it is 1, wherein,

[0041] D1x = W / 2*sign(D0x);

[0042] D1y = fy;

[0043] Limitshift = (W / 2 - sign(D0x)*fx)*sign(Originalshift);

[0044] When roll is 0 degree and ±180 degree, straight line FD0 is parallel to Y axis, since fx is not out of range, D0x is also not out of range, thus D0y is out of range, the first display position D1 of the point class symbol after position restriction and the first relative offset Limitshift are calculated by the second preset method (according to the following three formulas), wherein,

[0045] D1x = fx;

[0046] D1y = H / 2 * sign(D0y);

[0047] Limitshift = (H / 2 - sign(D0y) * fy) * sign(Originalshift)

[0048] If roll is not the preset angle, the following processing is performed:

[0049] The constant FD0b in the expression Y = FD0slope * X + FD0b of straight line FD0 is obtained,

[0050] FD0b = fy - FD0slope * fx;

[0051] The positions of four vertices of the display range are obtained, the slopes of the lines connecting the reference point F of the reference symbol and the four vertices E, G, K and H are calculated, which are respectively represented as FEslope, FGslope, FKslope and FHslope;

[0052] If D0x is greater than or equal to fx, i.e. D0 is located at the right side of F, and it is judged whether FD0slope is within the range of [FHslope, FGslope], the intersection point of straight line FD0 and the right boundary is calculated; if FD0slope is less than FHslope, the intersection point of straight line FD0 and the lower boundary is calculated; if FD0slope is greater than FGslope, the intersection point of straight line FD0 and the upper boundary is calculated;

[0053] If D0x is less than fx, i.e. D0 is located at the left side of F: if FD0slope is within the range of [FEslope, FKslope], the intersection point of straight line FD0 and the left boundary is calculated; if FD0slope is less than FEslope, the intersection point of straight line FD0 and the upper boundary is calculated; if FD0slope is greater than FKslope, the intersection point of straight line FD0 and the lower boundary is calculated;

[0054] The first display position D1 of the point class symbol after position restriction is determined according to the intersection point, since the position F is known, the distance FD1 can be obtained, and the first relative offset Limitshift of the point class symbol after position restriction can also be calculated, which is represented as Limitshift = FD1 * sign(Originalshift).

[0055] Further, the determining the second display position and the second relative offset after the position restriction of the dynamic directional line class symbol includes that the perpendicular point of the reference symbol to the line class dynamic directional symbol is a perpendicular line from a reference point of the reference symbol to the line class dynamic directional symbol, and an intersection point of the perpendicular line and the line class dynamic directional symbol is the perpendicular point, and the perpendicular point is a reference point of the line class dynamic directional symbol; specifically, in step three, the second display position of the line class dynamic directional symbol after the position restriction is located in a quadrilateral range surrounded by four straight lines passing through four vertices of a display range of the line class symbol and being parallel to the line class symbol, and the second relative offset after the position restriction is not greater than a distance from the reference symbol to the four straight lines passing through the four vertices of the display range and being parallel to the line class symbol, wherein the second display position and the second relative offset are determined as follows:

[0056] a reference point F2 of the reference symbol and coordinates (f2x, f2y) are obtained, a display range of the line class symbol is obtained as a rectangular range with a bearing direction WB degrees and a pitch direction HB degrees, an initial relative offset of the line class dynamic directional symbol is obtained as Originalshift2, the relative offset is a non-zero value (in the following processing, it is assumed that the relative offset is right positive and left negative), a rotation angle of the line class symbol relative to the reference symbol is obtained as roll2, it is assumed that a 12 o'clock direction is 0 degrees and counterclockwise increase, and the rotation angle roll2 includes

[0057] a display position D of the reference symbol to the line class symbol is determined.

[0058] Dx = f2x + Originalshift2*cos(roll2);

[0059] Dy = f2y + Originalshift2*sin(roll2);

[0060] it is judged whether D is out of the display range, if the bearing direction is located in a range of [-WB / 2, WB / 2] and the pitch direction is located in a range of [-HB / 2, HB / 2], D is not out of the display range, D is the second display position D2, and Originalshift2 is the second relative offset Limitshift2; otherwise, the position restriction needs to be performed.

[0061] since the slope of the straight line on which the line class symbol is located needs to be used in the position restriction process, the following processing is performed for a preset angle:

[0062] If roll2 is ±90 degrees, the straight line F2D is parallel to the Y axis, and because the display range of the dynamic directional symbol needs to be greater than or equal to the display range of the reference symbol, f2x is not out of range, so Dx is not out of range, and therefore Dy is out of range, the third preset method (the following three formulas) is used to calculate the second display position after position restriction and the second relative offset, wherein sign(X) is -1 when X is negative, and otherwise is 1,

[0063] D2x = f2x + Originalshift2 * sign(Dx);

[0064] D2y = f2y;

[0065] Limitshift2 = (HB / 2 - sign(Dy) * f2y) * sign(Originalshift2);

[0066] If roll2 is 0 degrees or ±180 degrees, the straight line F2D is parallel to the X axis, because f2y is not out of range, so Dy is not out of range, and therefore Dx is out of range, the fourth preset method (the following three formulas) is used to calculate the second display position after position restriction and the second relative offset:

[0067] D2x = f2x;

[0068] D2y = f2y + Originalshift2 * sign(Dy);

[0069] Limitshift2 = (WB / 2 - sign(Dx) * f2x) * sign(Originalshift2);

[0070] If roll is a non-preset angle, the following processing is performed:

[0071] Suppose that the straight line on which the line symbol is located is straight line BD, and straight line BD is perpendicular to straight line F2D, so the slope of straight line BD, BDslope, can be obtained according to the rotation angle, and is expressed as BDslope = tan(roll + 90)

[0072] According to the coordinates of the four vertices E2, G2, K2, and H2 of the display range and BDslope, the expressions of the four straight lines (i.e., the limiting lines) that pass through the four vertices and are parallel to straight line BD, BDslope * X + b[i] = Y, are obtained, and b[i] is expressed as follows,

[0073] Right upper vertex G2: b[0] = HB / 2 - WB / 2 * BDslope

[0074] Left lower vertex K2: b[1] = -HB / 2 + WB / 2 * BDslope

[0075] Top-left vertex E2: b[2] = HB / 2 + WB / 2 * BDslope

[0076] Bottom-right vertex H2: b[3] = -HB / 2 - WB / 2 * BDslope

[0077] Calculate the distance Len[i] from position F2 to the four limit lines, which is expressed as follows,

[0078]

[0079] If Originalshift2 is greater than 0, limit the second relative shift according to roll2:

[0080] When roll2 is in the range of (0, 90), the line class symbol can be farthest to the position passing through the top-right vertex G2 (corresponding to Len[0]) (the slope is still BDslope);

[0081] When roll2 is in the range of (90, 180), the line class symbol can be farthest to the position passing through the top-left vertex E2 (corresponding to Len[2]) (the slope is still BDslope);

[0082] When roll2 is in the range of (-90, 0), the line class symbol can be farthest to the position passing through the bottom-right vertex H2 (corresponding to Len[3]) (the slope is still BDslope);

[0083] When roll2 is in the range of (-180, -90), the line class symbol can be farthest to the position passing through the bottom-left vertex K2 (corresponding to Len[1]) (the slope is still BDslope);

[0084] Use the numerical limiting operation Out = LIMIT(In, Min, Max), where the operation input is data In, the lower limit Min and the upper limit Max, and the operation output is data Out: when In is greater than Max, the operation output is Max; when In is less than Min, the operation output is Min; when In is in the range of [Min, Max], the operation output is In; according to the judgment result of roll2, combined with the numerical limiting operation, the second relative shift Limitshift2 after position limitation is calculated, which is expressed as,

[0085] Second relative shift Limitshift2 = LIMIT(Originalshift2, 0, len[i]);

[0086] If the second relative shift Originalshift2 is less than 0, limit the relative shift according to roll2:

[0087] When roll2 is in the range of (0, 90), the line symbol can reach at most the position passing through the lower-left vertex K2 (corresponding to Len[1]) (the slope is still BDslope) ;

[0088] When roll2 is in the range of (90, 180), the line symbol can reach at most the position passing through the lower-right vertex H2 (corresponding to Len[3]) (the slope is still BDslope) ;

[0089] When roll2 is in the range of (-90, 0), the line symbol can reach at most the position passing through the upper-left vertex E2 (corresponding to Len[2]) (the slope is still BDslope) ;

[0090] When roll2 is in the range of (-180, -90), the line symbol can reach at most the position passing through the upper-right vertex G2 (corresponding to Len[0]) (the slope is still BDslope) ;

[0091] According to the judgment result of roll2, in combination with the numerical limiting operation, the second relative shift after position limiting is calculated, expressed as Limitshift2 = LIMIT (Originalshift2, -len[i], 0) ;

[0092] According to the display position F2 of the reference symbol and the second relative shift Limitshift2, the second display position D2 of the line symbol after limiting can be obtained,

[0093] D2x = f2x + Limitshift2*cos(roll2)

[0094] D2y = f2y + Limitshift2*sin(roll2).

[0095] Before the position restriction algorithm is applied, it is necessary to determine whether the dynamic directional symbol belongs to the dynamic directional symbol; if yes, it is necessary to further determine which type of dynamic directional symbol it belongs to, and determine the corresponding display range boundary; then according to the category, the corresponding position restriction algorithm is selected, and the Nth display position of the dynamic directional symbol after position restriction and the Nth relative offset of the dynamic directional symbol after position restriction (N is one or two) are obtained. For the aiming display system which depends on the specific position of the symbol for drawing, the display position of the dynamic directional symbol in the picture can be determined according to the Nth display position of the dynamic directional symbol, and then drawing; for the aiming display system which depends on the relative relationship of the symbol for drawing, the display position of the dynamic directional symbol in the picture can be determined according to the position of the reference symbol, the rotation angle and the Nth relative offset of the dynamic directional symbol, and then drawing. The position restriction requirements of point type and line type dynamic directional symbols are fully considered, and the corresponding position restriction algorithms are given, which can effectively solve the problem that the dynamic directional symbol cannot be observed when it exceeds the display range.

[0096] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A position constraint algorithm for dynamic directional symbols based on relative offset, applicable to aiming display in airborne display devices, characterized in that, The location restriction algorithm includes the following steps: Step 1: Determine the display range of dynamic directional symbols on the display interface. Dynamic directional symbols include dot symbols and line symbols. Step 2: Calculate the theoretical display position based on the characteristics of the dot-type symbols. When the angle is preset, the first preset method and the second preset method are used for processing. When the angle is not preset, the slope range of the connecting line between the reference symbol and the dot-type symbol is judged to determine the first display position and the first relative offset after the dynamic directional dot-type symbol position restriction. Specifically, when the preset angle is the rotation angle roll1 of the dot-type symbol relative to the reference symbol equal to ±90 degrees, the first preset method is used for determination. When the preset angle is the rotation angle roll1 of the dot-type symbol relative to the reference symbol equal to 0 degrees or ±180 degrees, the second preset method is used for determination. Step 3: Calculate the perpendicular point from the reference symbol to the line symbol based on the characteristics of the line symbol. If it is a preset angle, use the third and fourth preset methods. If it is a non-preset angle, determine the expression of the four straight lines that pass through the four vertices of the display range and are parallel to the line symbol. By judging the sign of the relative offset and using the distance from the reference symbol to the four straight lines, determine the second display position and the second relative offset after the dynamic directional line symbol position restriction. Specifically, when the preset angle is the rotation angle roll2 of the line symbol relative to the reference symbol equal to ±90 degrees, the third preset method is used for determination. When the preset angle is the rotation angle roll2 of the point symbol relative to the reference symbol equal to 0 degrees or ±180 degrees, the fourth preset method is used for determination. Step 4: Based on the first display position and the display position of the first relative offset control point symbol in the screen, and based on the second display position and the display position of the second relative offset control line symbol in the screen, wherein OpenGL is used to draw dynamic directional line symbols based on the second display position and the second relative offset position, and display them to guide the airborne sensors to search, identify and track.

2. The position restriction algorithm according to claim 1, characterized in that... The dynamic directional symbol is a dynamic symbol that rotates around a reference symbol and has a positional offset relative to the reference symbol.

3. The position restriction algorithm according to claim 2, characterized in that, The point-type symbols are those for which only the reference point needs to be considered when restricting their position, without needing to consider the size of the symbol itself; the line-type symbols are those for which both the reference point and the size of the symbol itself need to be considered when restricting their position.

4. The position restriction algorithm according to claim 1, characterized in that... The preset angles are 0 degrees, ±90 degrees, and ±180 degrees.

5. The position restriction algorithm according to claim 3, characterized in that... Determine the first display position and the first relative offset after the position limit of the dynamic directional point-type symbol; The second display position and the second relative offset after the position limit of the dynamic directional line symbol are determined. Since the first and second relative offsets are directional, they are positive and negative. The positive and negative signs of the relative offset after the position limit are the same as the positive and negative signs of the relative offset in the initial state.

6. The position restriction algorithm according to claim 5, characterized in that... When the angle is not preset, the slope range of the connecting line between the reference symbol and the point-type symbol is determined by judging the range of the angle range. For point-type dynamic directional symbols, the connecting line is the line connecting the reference point of the reference symbol and the reference point of the point-type dynamic directional symbol. The slope of the connecting line at the non-preset angle is determined, where... The slope of the connecting line with a non-preset angle is denoted as slope FD0slope, and we can obtain... FD0slope = tan(roll + 90), where roll is a non-preset angle.

7. The position restriction algorithm according to claim 6, characterized in that, When a point-type dynamic directional symbol exceeds its corresponding display range, after position restriction, the intersection of the connecting line of the point-type dynamic directional symbol and the boundary of its corresponding display range is taken as the first display position of the point-type dynamic directional symbol after position restriction, thereby obtaining the first relative offset, including, Obtain the reference point F of the reference symbol with coordinates (fx, fy); obtain the rectangular range corresponding to the dynamic directional symbol, which is the azimuth direction W degrees and the pitch direction H degrees; obtain the relative offset of the point-type dynamic directional symbol as Originalshift, which is a non-zero value; first calculate the theoretical display position D0 (D0x, D0y) of the point-type dynamic directional symbol; then determine whether D0 exceeds the display range. If it does, restrict the position of D0 to obtain the first display position D1 (D1x, D1y) of the point-type symbol after restriction and its corresponding first relative offset Limitshift after position restriction. Theoretical calculations show that the position is D0, and D0x = fx – Originalshift * sin(roll); D0y = fy + Originalshift * cos(roll); Determine if D0 exceeds the display range. If the azimuth direction is within the range of [-W / 2, W / 2] and the pitch direction is within the range of [-H / 2, H / 2], then it does not exceed the display range. D0 is the first display position D1 of the dot symbol, and Originalshift is the first relative offset Limitshift. Otherwise, position restrictions are applied. When roll1 is ±90 degrees, the straight line FD0 is parallel to the X-axis. Since the display range of the dynamic directional symbol must be greater than or equal to the display range of its reference symbol, fy does not exceed the limit, and therefore D0y does not exceed the limit either. Thus, D0x exceeds the limit. The first display position D1 and the first relative offset Limitshift after position limitation are calculated using the first preset method, where sign(X) has a value of -1 if X is negative and 1 otherwise. The first preset method is: D1x = W / 2 * sign(D0x), D1y = fy and Limitshift = (W / 2 –sign(D0x) * fx) * sign(Originalshift); When roll1 is 0 degrees and ±180 degrees, the straight line FD0 is parallel to the Y-axis. Since fx does not exceed the limit, D0x also does not exceed the limit. Therefore, D0y exceeds the limit. The first display position D1 and the first relative offset Limitshift after position limitation are calculated using the second preset method. The second preset method is D1x = fx, D1y = H / 2 * sign(D0y) and Limitshift = (H / 2 – sign(D0y) * fy) * sign(Originalshift); If the roll angle is not a preset angle, the following steps will be taken: Find the constant FD0b in the expression Y = FD0slope * X + FD0b for the line FD0, where FD0b = fy - FD0slope * fx; Get the positions of the four vertices of the display range, and calculate the slopes of the lines connecting the reference point F to the four vertices E, G, K, and H, which are represented as FEslope, FGslope, FKslope, and FHslope, respectively. If D0x is greater than or equal to fx, that is, D0 is located to the right of F, and if FD0slope is within the range of [FHslope, FGslope], then calculate the intersection point of line FD0 with the right boundary; if FD0slope is less than FHslope, then calculate the intersection point of line FD0 with the lower boundary; if FD0slope is greater than FGslope, then calculate the intersection point of line FD0 with the upper boundary. If D0x is less than fx, that is, D0 is to the left of F: if FD0slope is within the range of [FEslope, FKslope], then calculate the intersection of line FD0 with the left boundary; if FD0slope is less than FEslope, then calculate the intersection of line FD0 with the upper boundary; if FD0slope is greater than FKslope, then calculate the intersection of line FD0 with the lower boundary. Based on the intersection point, determine the first display position D1 of the point-type symbol after position restriction, and calculate the first relative offset Limitshift of the point-type symbol after restriction, which is expressed as Limitshift = FD1 * sign(Originalshift).

8. The position restriction algorithm according to claim 7, characterized in that, The second display position and the second relative offset after determining the position limit of the dynamic directional line symbol include, The perpendicular point from the reference symbol to the line-type dynamic directional symbol is the point where a perpendicular line is drawn from the reference point of the reference symbol to the line-type dynamic directional symbol, and the intersection of the perpendicular line and the line-type dynamic directional symbol is taken as the perpendicular point, which is also the reference point of the line-type dynamic directional symbol.

9. The position restriction algorithm according to claim 8, characterized in that, In step three, after position restriction, the second display position of the line-type dynamic directional symbol will be located within the quadrilateral area enclosed by four straight lines passing through the four vertices of the display range and parallel to the line-type symbol. Furthermore, the second relative offset after position restriction will not be greater than the distance from the reference symbol to the four straight lines passing through the four vertices of the display range and parallel to the line-type symbol. Obtain the reference point F2 of the reference symbol with coordinates (f2x, f2y); obtain the rectangular range corresponding to the line symbol, which is the azimuth direction WB degrees and the pitch direction HB degrees; obtain the initial relative offset of the dynamic directional line symbol as Originalshift2, where the relative offset is a non-zero value; obtain the rotation angle of the line symbol relative to the reference symbol as roll2, including... Determine the display position of the reference symbol F2 to the perpendicular point position D(Dx, Dy) of the line symbol; Dx = f2x + Originalshift2 * cos(roll2); Dy = f2y + Originalshift2 * sin(roll2); Determine if D exceeds the display range. If the azimuth direction is within the range of [-WB / 2, WB / 2] and the pitch direction is within the range of [-HB / 2, HB / 2], then it does not exceed the display range, and D is the second display position D2, and Originalshift2 is the second relative offset Limitshift2; otherwise, position restrictions are required. Because the slope of the line containing the line symbol is required during the positional constraints, the preset angle is handled as follows: If roll2 is ±90 degrees, the straight line F2D is parallel to the Y-axis. Since the display range of the dynamic directional symbol must be greater than or equal to the display range of its reference symbol, f2x does not exceed the limit, so Dx does not exceed the limit either. Therefore, Dy exceeds the limit. The second display position and the second relative offset after the position limit are calculated using the third preset method. In this method, sign(X) has a value of -1 when X is negative and 1 otherwise. The third preset method is D2x=f2x+Originalshift2*sign(Dx), D2y=f2y, and Limitshift2 = (HB / 2–sign(Dy) * f2y) * sign(Originalshift2); If roll2 is 0 degrees or ±180 degrees, the line F2D is parallel to the X-axis. Since f2y does not exceed the limit, Dy also does not exceed the limit. Therefore, Dx exceeds the limit. The second display position and the second relative offset after position limitation are calculated using the fourth preset method. The fourth preset method is D2x=f2x, D2y=f2y+Originalshift2*sign(Dy) and Limitshift2 = (WB / 2 - sign(Dx) * f2x) * sign(Originalshift2); If the roll angle is not a preset angle, the following steps will be taken: Assuming the line containing the line symbol is line BD, then line BD is perpendicular to line F2D. Therefore, the slope of line BD, BDslope, can be obtained from the rotation angle, which is expressed as BDslope = tan(roll + 90). Given the coordinates of the four vertices E2, G2, K2, and H2 of the display range and BDslope, find the four lines that pass through the four vertices and are parallel to line BD. The expression BDslope * X + b[i] = Y, where b[i] is represented as follows: Top right vertex G2: b[0] = HB / 2 - WB / 2 * BDslope Lower left vertex K2: b[1] = -HB / 2 + WB / 2 * BDslope Top left vertex E2: b[2] = HB / 2 + WB / 2 * BDslope The lower right vertex H2: b[3] = -HB / 2 - WB / 2 * BDslope The distance Len[i] from position F2 to the four constraint lines is calculated as follows: If Originalshift2 is greater than 0, then limit the second relative offset according to roll2: When roll2 is in the range (0, 90), the farthest line symbol can reach is the position passing through the top right vertex G2; When roll2 is within the range of (90, 180), the farthest line symbol can reach is the position passing through the top left vertex E2; When roll2 is in the range (-90, 0), the farthest line symbol can reach is the position passing through the bottom right vertex H2; When roll2 is in the range (-180, -90), the furthest line symbol can reach is the position passing through the lower left vertex K2; The numerical limiting operation `Out = LIMIT(In, Min, Max)` is used, where the input is the data `In`, the lower limit boundary `Min`, and the upper limit boundary `Max`, and the output is the data `Out`. The output is `Max` when `In` is greater than `Max`, `Min` when `In` is less than `Min`, and `In` when `In` is within the range [Min, Max]. Based on the result of `roll2`, ​​the second relative offset `Limitshift2` after position limiting is calculated, expressed as... Second relative offset Limitshift2 = LIMIT(Originalshift2, 0, len[i]); If the second relative offset Originalshift2 is less than 0, then limit the relative offset according to roll2: When roll2 is in the range (0, 90), the farthest position that the line symbol can reach is the position passing through the lower left vertex K2; When roll2 is in the range (90, 180), the furthest position that the line symbol can reach is the position passing through the lower right vertex H2; When roll2 is in the range (-90, 0), the furthest position that this line symbol can reach is the position passing through the top left vertex E2; When roll2 is in the range (-180, -90), the farthest position that this line symbol can reach is the position passing through the upper right vertex G2; Based on the judgment result of roll2, combined with the numerical limiting operation, the second relative offset after position limitation is calculated, which is expressed as Limitshift2 = LIMIT(Originalshift2, -len[i], 0); Based on the display position F2 of the reference symbol and the second relative offset Limitshift2, the second display position D2 of the constrained line symbol can be obtained. D2x = f2x + Limitshift2 * cos(roll2), D2y = f2y + Limitshift2 * sin(roll2).

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