A method for automatically extracting flight procedure data from aeronautical charts

Abstract

The application discloses a method for automatically extracting flight procedure data from a navigation chart. It belongs to the field of electronic digital data processing. The method comprises the following steps: setting a navigation chart layout template; obtaining a navigation chart file mark text; extracting a waypoint and calculating a coordinate conversion relationship; extracting a line segment and converting the line segment into a track segment; assigning a value to the track segment and combining the track segment into a flight track; and generating a flight track object and converting the flight track object into an XML file. The method can automatically extract a flight procedure track from a terminal area navigation chart to generate a digital flight procedure, thereby providing data support for applications such as digital navigation charts.

Description

Technical Field

[0001] This invention relates to the field of data processing technology, and in particular to a method for automatically extracting flight procedure data from aeronautical charts. Background Technology

[0002] Flight procedures are derived from aeronautical charts such as instrument approach charts, instrument departure charts, and instrument approach charts published by civil aviation authorities of various countries. Flight procedures in aeronautical charts are represented by flight paths along with annotations such as names, magnetic headings, altitudes, and distances.

[0003] To enable automated calculation and analysis of flight procedures, these procedures need to be converted into structured data. Currently, major global navigation data providers use officially published aeronautical charts to manually encode flight procedures into ARINC424 format. This manual coding process is inefficient and requires specially trained personnel.

[0004] The ARINC424 encoding format is primarily designed for use by airborne flight management computers. Its data structure is complex and does not include flight trajectory graphic data. Other application systems, such as flight planning systems and performance analysis systems, require cumbersome operations such as decoding ARINC424 format flight data and restoring trajectory graphics before they can use the flight program data for applications such as digital chart flight trajectory display, flight distance and fuel calculation.

[0005] As civil aviation becomes increasingly digitalized, the AIXM5.1 data exchange standard has become the new standard for the entire industry. The civil aviation industry needs a simple and easy-to-use AIXM5.1 format flight procedure data and creation method that includes all flight procedure elements on aeronautical charts and includes trajectory graphic information.

[0006] Citation 1: Chinese Invention Patent, "A Method for Data Modeling and Information Extraction of Flight Routes", Authorization Announcement No.: CN110674216B. This invention discloses a method for extracting flight procedures from flight routes in a navigation database. This method requires providing an underlying navigation database and pre-compiling flight procedure data and storing it in a navigation database file. It is only applicable to airborne flight management computers, and other application systems have difficulty obtaining flight procedure data, thus limiting its application scope.

[0007] Citation 2: Chinese Invention Patent, "A Method and Apparatus for Checking and Controlling Flight Procedure Track Data," Authorization Announcement No.: CN111444174B. This invention discloses a method for generating flight procedure tracks using the PBN database encoding table in the aeronautical data compilation, according to the ARINC424 path termination code type and the combination of preceding and following segments. This method is only applicable to PBN flight procedures for which the database encoding table has been published; it cannot reconstruct the tracks of traditional flight procedures, and the generated tracks are not entirely consistent with the flight tracks published on the aeronautical charts. Summary of the Invention

[0008] To address the long-standing drawback that digital flight procedures can only rely on manually generated ARINC424 format data and cannot be reconstructed into flight trajectories from aeronautical charts, the method invented in this application realizes a method for automatically extracting flight procedure trajectories and marker text related information from terminal area aeronautical chart PDF files, and can convert the extracted data into the AIXM5.1 standard format.

[0009] To achieve the above objectives, the present invention includes the following steps:

[0010] S1: Set the layout template of the aeronautical chart and the feature recognition template of the aeronautical chart unit; establish the flight procedure model.

[0011] S2: Parse the PDF terminal area aeronautical chart file and obtain the Markdown formatted markup text.

[0012] S3: Based on the layout template, extract the airport, runway, navigation method, and effective date data of the aeronautical chart from the marked text.

[0013] S4: Based on the feature recognition template, extract the names and map coordinates of all waypoints from the marked text, and derive the conversion relationship between map coordinates and latitude and longitude coordinates.

[0014] Furthermore, the derivation process for the conversion relationship between map sheet coordinates and latitude and longitude coordinates is as follows:

[0015] S4-1: Select the two waypoints P1 and P2 that are farthest apart from all waypoints on the aeronautical chart, with their map coordinates being (X1, Y1) and (X2, Y2) respectively; extract the latitude and longitude coordinates of waypoints P1 and P2 from the waypoint database according to their names, which are (Lat1, Lon1) and (Lat2, Lon2) respectively.

[0016] S4-2: Given the map coordinates (X3, Y3) of another point P3 on the aeronautical chart, calculate the latitude and longitude coordinates of P3:

[0017] S4-2-1: Based on the latitude and longitude coordinates and map coordinates of P1 and P2, calculate the actual distance from P1 to P2 and the distance on the map, respectively.

[0018] The aeronautical chart scale Sc is calculated using the formula: Scale = Distance on map / Actual distance.

[0019] Based on the map coordinates of P1, the distance and direction from P1 to the origin P0 of the map coordinate system are obtained. The actual distance between P1 and P0 is calculated according to the scale. Based on the actual distance and direction, the latitude and longitude coordinates (Lat0, Lon0) of the origin P0 of the map coordinate system are calculated.

[0020] S4-2-2: Calculate the actual horizontal distance Xm = X3×Sc and the actual vertical distance Ym = Y3×Sc from P3 to the origin P0.

[0021] S4-2-3: Calculate the latitude and longitude coordinates of P3: Latitude Lat3 = Lat0 + Ym / R; Longitude Lon3 = Lon0 + Xm / (R×cos(Lat0)); where R is the Earth's radius.

[0022] S5: Extract the map coordinates of all graphic elements of type line segment from the marked text, and convert the line segments into trajectory segments.

[0023] Furthermore, the process of converting a line segment into a trajectory segment includes:

[0024] S5-1: Calculate the length and direction of the line segment based on the map coordinates. Line segments exceeding a threshold δ are designated as straight line segments, while those shorter than δ are designated as curve segments. Connected curve segments with equal increasing or decreasing directions are merged into arc segment segments. The center coordinates and radius of the arc segment are calculated, and all points on the arc segment are regenerated based on these coordinates.

[0025] S5-2: Based on the conversion relationship, convert the map coordinates of all points on the trajectory segment to latitude and longitude coordinates, and calculate the actual distance of the trajectory segment based on the latitude and longitude coordinates.

[0026] S6: Based on the feature recognition template, extract the map coordinates and text layout direction of five chart units (flight procedure name, altitude, speed, distance, and magnetic heading) from the marked text.

[0027] S7: Match chart units with track segments and combine track segments into multiple flight paths.

[0028] Furthermore, S7 includes:

[0029] S7-1: Compare the five chart units (flight procedure name, altitude, speed, distance, and magnetic heading) with the track segment. If the chart unit and the track segment are adjacent and the text layout direction of the chart unit is consistent with the direction of the track segment, then match the text information of the chart unit to the track segment object.

[0030] S7-2: Combines multiple trajectory segments with the same flight procedure name into a single flight trajectory.

[0031] S7-3: For discontinuous flight paths, insert a flight path segment that does not have a flight procedure name but is connected to the flight path into the flight path.

[0032] S8: Assign the airport, runway, navigation method, and effective date to each flight path to generate a flight procedure model object.

[0033] S9: Convert the flight procedure model object into an XML file according to the AIXM5.1 data standard.

[0034] The present invention has the following advantages:

[0035] This invention enables the automatic extraction of flight procedure data and trajectories directly from officially published aeronautical charts. The extracted trajectories perfectly match the charts, with consistent graphic representation and distances. This method allows for batch extraction of flight procedures from aeronautical charts, overcoming the drawback of requiring significant manual labor in creating ARINC424 encoded data and greatly improving the efficiency of digital flight procedure creation. The data extracted by this method can be used not only in aeronautical chart platforms and analysis software but also as initial data for AIXM5.1 data or ARINC424 encoded data. Attached Figure Description

[0036] Figure 1 A diagram illustrating the main steps involved in generating flight procedure data according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the process for generating flight procedure data according to an embodiment of the present invention;

[0038] Figure 3 This is a standard departure flight procedure diagram for ZXXX Airport;

[0039] Figure 4 A screenshot of the Markdown-formatted marked text extracted from the aeronautical chart;

[0040] Figure 5 To extract a schematic diagram of the graphic unit;

[0041] Figure 6 Generate schematic diagrams of all flight procedure trajectories. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0043] Currently, the primary carrier of flight procedures is ARINC424 encoded data. However, ARINC424 format flight procedures present numerous inconveniences in both creation and application. First, ARINC424 encoding can only be created by specially trained personnel, a cumbersome and inefficient process. Second, ARINC424 data lacks graphical data of the flight trajectory; the flight trajectory must be deduced from the encoded data, resulting in discrepancies between the deduced trajectory and the chart trajectory. As civil aviation becomes increasingly digitalized, ARINC424 format flight procedures cannot meet users' demands for flight procedure data.

[0044] Based on this, the present invention proposes a method for automatically extracting flight procedure data from aeronautical chart files, which can quickly and in batches extract flight procedure data from terminal area aeronautical chart PDF files, and can convert the flight trajectory in the aeronautical chart into graphical data.

[0045] One embodiment of the present invention is a process for generating flight trajectory data using this method.

[0046] like Figure 1 As shown, one embodiment of the present invention includes the following steps:

[0047] S1: Set the chart layout template and chart unit feature recognition template, and establish a flight procedure model;

[0048] S2: Parse the aeronautical chart file to obtain the marked text;

[0049] S3: Extract airport runway information from tagged text;

[0050] S4: Derive the conversion relationship between map sheet coordinates and latitude and longitude coordinates;

[0051] S5: Extract line segments and convert them into trajectory segments;

[0052] S6: Extract aeronautical chart units;

[0053] S7: Combine trajectory segments into a flight trajectory;

[0054] S8: Generate flight procedure model object;

[0055] S9: Convert flight procedure model objects into XML files.

[0056] The detailed processing procedure of this embodiment is as follows: Figure 2 As shown:

[0057] S1: Set the layout template of the aeronautical chart and the feature recognition template of the aeronautical chart unit; establish the flight procedure model.

[0058] Establish chart layout templates for different countries and chart types, including standard instrument approach charts, approach charts, and approach charts required by the International Civil Aviation Organization. Figure 3 The layout templates for each type of terminal area aeronautical chart. Each chart type's layout template includes the chart orientation, chart type, airport, runway, navigation method, and the location of the effective date on the chart.

[0059] like Figure 3 As shown, this embodiment selects a standard instrument departure chart of an airport (code name ZXXX). The chart direction is set to vertical according to the text direction in the upper left corner, the chart type text "standard instrument departure chart" is set to the upper left corner of the chart, the airport name is set to the lower right corner of the chart, the runway text "RWY01 / 36L / 36R" is set to the upper right corner of the chart, the navigation method text "RNAV" is set to the left of the runway information, and the effective date text "2021-10-1" is set to the lower left corner of the chart.

[0060] The chart unit includes six chart elements: waypoints, flight procedure name, altitude, speed, distance, and magnetic heading. The waypoint feature recognition template is set as follows: the icon shape is a hollow four-pointed star, and the text format is two letters followed by three numbers; or the shape is a solid triangle, the text format is five letters, and the text position feature is adjacent waypoint icons arranged horizontally.

[0061] The flight procedure model includes eight attributes: flight procedure name, airport, runway, origin, destination, navigation method, effective date, and trajectory segment. The trajectory segment includes six attributes: origin, destination, magnetic heading, altitude, speed, and trajectory coordinate point string.

[0062] S2: Parse the ZXXX airport departure map PDF file and extract the Markdown-formatted markup text, such as... Figure 4 As shown.

[0063] S3: Based on the layout template, extract the airport, runway, navigation method, and effective date data from the marked text. Airport = "ZXXX", Runway = "RWY01 / 36L / 36R", Navigation Method = "RNAV", Effective Date = "2021-10-1".

[0064] S4: Based on the feature recognition template, extract the names and map coordinates of all waypoints from the marked text, and derive the conversion relationship between map coordinates and latitude and longitude coordinates.

[0065] S4-1: From Figure 3In the shown aeronautical chart, the map sheet distances of each point are calculated, and the two points with the greatest distance are determined: BOTPU point located in the upper left and IGMOR point in the lower right, with map sheet coordinates of (47,149) and (288,12) respectively. The latitude and longitude coordinates of these two points are found to be (N395938, E1172849) and (N384911, E1180127) respectively, from the built-in waypoint database.

[0066] S4-2: This function can calculate the latitude and longitude coordinates of any point on a flight chart, such as... Figure 3 Point AA437 on the upper left side, whose map coordinates are (72, 189) can be determined from the marked text. The process of finding the latitude and longitude coordinates of AA437 is as follows:

[0067] S4-2-1: Based on the latitude and longitude coordinates and map sheet coordinates of two known points, BOTPU and IGMOR, calculate:

[0068] Based on latitude and longitude coordinates, the actual distance from BOTPU to IGMORP is calculated to be 225,000 meters.

[0069] Based on the map coordinates, the distance from BOTPU to IGMORP point on the map is calculated to be 277 mm;

[0070] Therefore, the chart scale Sc is: (277 / 225000000) = 1:812274;

[0071] The distance from BOTPU to the origin P0 (lower left corner of the aeronautical chart) is calculated to be 156 mm, with a direction of 72.5°. According to the scale, the distance from BOTPU to point P0 is 126714 meters. Therefore, the latitude and longitude coordinates of the origin P0 are obtained as (Lat0 = N393804, Lon0 = E1140355).

[0072] S4-2-2: Calculate the actual lateral distance Xm = 58484 meters and the actual longitudinal distance Ym = 153520 meters from AA437 to the origin P0.

[0073] S4-2-3: Calculate the latitude and longitude coordinates of P3: Latitude Lat3 = Lat0 + Ym / R; Longitude Lon3 = Lon0 + Xm / (R×cos(Lat0)); where R is the Earth's radius of 6,371,393 meters;

[0074] The latitude and longitude coordinates of point AA437 can be calculated as (N401803, E1154459).

[0075] Based on the above process, the actual latitude and longitude coordinates of any point on the aeronautical chart can be calculated from the map sheet coordinates of that point.

[0076] S5: Extract the map coordinates of all graphic elements of type line segment from the marked text, and convert the line segments into trajectory segments.

[0077] S5-1: Calculate the length and direction of the line segment based on the map coordinates. Set line segments whose length exceeds the threshold by 1 cm as straight trajectory segments.

[0078] Line segments shorter than 1 cm are designated as curve segments. Curve segments that are connected end-to-end and whose direction increases or decreases by the same amount are merged into an arc trajectory segment.

[0079] Calculate the center coordinates and radius of the arc trajectory segment, and regenerate all points on the arc trajectory segment based on the center coordinates and radius.

[0080] S5-2: Based on the conversion relationship, convert the map coordinates of all points on the trajectory segment to latitude and longitude coordinates, and calculate the actual distance of the trajectory segment based on the latitude and longitude coordinates.

[0081] S6: Based on the feature recognition template, extract the map sheet coordinates and text layout direction of five chart units—flight procedure name, altitude, speed, distance, and magnetic heading—from the marked text, such as... Figure 5 As shown.

[0082] S7: Match chart units with track segments and combine track segments into multiple flight paths.

[0083] S7-1: Compare the five chart units (flight procedure name, altitude, speed, distance, and magnetic heading) with the track segment. If the chart unit and the track segment are adjacent and the text layout direction of the chart unit is consistent with the direction of the track segment, then match the text information of the chart unit to the track segment object.

[0084] S7-2: Combines multiple trajectory segments with the same flight procedure name into a single flight trajectory.

[0085] S7-3: For discontinuous flight paths, insert a flight path segment that does not have a flight procedure name but is connected to the flight path into the flight path.

[0086] like Figure 6 As shown, for Figure 3 All flight paths formed after processing the departure procedure diagram.

[0087] S8: Assign the airport, runway, navigation method, and effective date to each flight path to generate a flight procedure model object.

[0088] S9: Convert the flight procedure model object into an XML file according to the AIXM5.1 data standard.

[0089] The above description is merely one embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for automatically extracting flight procedure data from aeronautical charts, characterized in that, Includes the following steps: S1: Set the layout template of the aeronautical chart and the feature recognition template of the aeronautical chart unit; establish the flight procedure model; S2: Parse the PDF terminal area aeronautical chart file and obtain the Markdown formatted markup text; S3: Based on the layout template, extract the airport, runway, navigation method, and effective date data of the aeronautical chart from the marked text; S4: Based on the feature recognition template, extract the names and map coordinates of all waypoints from the marked text, and derive the conversion relationship between map coordinates and latitude / longitude coordinates, including: S4-1: Select the two waypoints P1 and P2 that are farthest apart from the waypoints, with map coordinates of (X1, Y1) and (X2, Y2) respectively; extract the latitude and longitude coordinates of waypoints P1 and P2 from the waypoint database according to their names, which are (Lat1, Lon1) and (Lat2, Lon2) respectively. S4-2: Given the map coordinates (X3, Y3) of another point P3 on the aeronautical chart, calculate the latitude and longitude coordinates of P3: S4-2-1: Based on the latitude and longitude coordinates of P1 and P2 and the map sheet coordinates, calculate the aeronautical chart scale Sc and the latitude and longitude coordinates (Lat0, Lon0) of the origin P0 of the map sheet coordinate system. S4-2-2: Calculate the actual horizontal distance Xm = X3 × Sc and the actual vertical distance Ym = Y3 × Sc from P3 to the origin P0 of the map coordinate system; S4-2-3: Calculate the latitude and longitude coordinates of P3: Latitude Lat3 = Lat0 + Ym / R; Longitude Lon3 = Lon0 + Xm / (R × cos(Lat0)); where R is the Earth's radius; S5: Extract the map coordinates of all graphic elements of type line segment from the marked text, and convert the line segments into trajectory segments, including: S5-1: Calculate the length and direction of the line segment based on the map coordinates; set line segments with a length exceeding the threshold δ as straight line segments; set line segments with a length less than δ as curve segments; merge curve segments that are connected end to end and whose directions increase or decrease by the same amount into arc trajectory segments; calculate the center coordinates and radius of the arc trajectory segment; and regenerate all points on the arc trajectory segment based on the center coordinates and radius. S5-2: Based on the conversion relationship, convert the map coordinates of all points on the trajectory segment into latitude and longitude coordinates, and calculate the actual distance of the trajectory segment based on the latitude and longitude coordinates; S6: Based on the feature recognition template, extract the map sheet coordinates and text layout direction of five chart units (flight procedure name, altitude, speed, distance, and magnetic heading) from the marked text; S7: Match chart units with track segments, and combine track segments into multiple flight paths, including: S7-1: Compare the five chart units (flight procedure name, altitude, speed, distance, and magnetic heading) with the track segment. If the chart unit and the track segment are adjacent and the text layout direction of the chart unit is consistent with the direction of the track segment, then match the chart unit to the track segment. S7-2: Combine multiple trajectory segments with the same flight procedure name into a single flight trajectory; S7-3: For discontinuous flight paths, insert a flight path segment that does not have a flight procedure name but is connected to the flight path into the flight path; S8: Assign the airport, runway, navigation method, and effective date to each flight path to generate the flight procedure model object; S9: Convert the objects of the flight procedure model into XML files according to the AIXM5.1 data standard.

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