Historical paper tide record sheet digitalization method and device and computer equipment

Abstract

The invention discloses a historical paper tide record chart digitalization method and device and computer equipment, and the method comprises the steps: converting a historical paper tide record chart into an electronic format to generate a tide table image, and carrying out the geometric calibration; establishing a vector line layer based on the geometrically calibrated tide table image, and collecting a tide curve in the tide table image in an interactive digital mode; adjusting the ordinate of the tide curve, and splicing to obtain a complete tide curve; selecting a tide level record array and a high-low tide array at the hourly moment to accurately correct the complete tide curve to obtain tide level curve data consistent with an actual record value; and evaluating the precision of the tide level curve data according to the tide level record array at the hourly moment, and obtaining water level data at equal time intervals to obtain a digital tide data set. According to the method, the historical paper tide record chart can be processed in batches, the missing part can be automatically filled, the precision of the tide level curve data is improved, and digital analysis of historical tide data is facilitated.

Description

Technical Field

[0001] This application relates to the technical field of data processing, and in particular, to a method, device, and computer device for digitizing historical paper tide records. Background Art

[0002] Before the popularization of digital tide recorders, tide data and archives were mainly in paper records. Paper tide record data is important archival data for analyzing the tide laws of tide gauge stations and the changes in sea level, and is valuable historical archival data of tide gauge stations. In the early days of the founding of the People's Republic of China, hourly water level data along the coast of China was recorded in the form of paper print records. Tide gauge stations with archived paper tide tables usually have an earlier establishment time and have accumulated long-term and continuous observation data, providing first-hand observation data for analyzing the trend of sea level change and reconstructing historical ocean dynamic disaster processes.

[0003] However, paper materials are not conducive to the analysis, sharing, and use of historical water level data. Therefore, digitizing paper historical tide data for data analysis and information sharing is a basic task. Because during the storage and use of paper tide record data, affected by factors such as deformation and damage of paper media, the data quality will be affected. At the same time, paper tide data cannot be directly used for numerical analysis. When paper tide data is used for analyzing sea level change, historical tide level change, and historical ocean water level anomaly change, the paper tide data needs to be digitized.

[0004] It can be seen that digitizing historical paper tide record data is an effective way to explore the value of historical data and promote the information sharing of archival materials. Carrying out the digitization work of paper tide historical observation data has important reference value for analyzing sea level change, studying tide laws, and ocean disaster warning.

[0005] Currently, the digitization of tide tables is achieved based on graphic recognition technology. Image segmentation is the key to automatically identifying water level curves. However, due to the color differences between tide record papers of different tide gauge stations and different time batches and the tide curves on the map, it is difficult to specify a unified threshold parameter for image segmentation, which is not conducive to batch data processing. In addition, individual tide curves have problems such as broken ink, uneven thickness of water level curves, and the existence of mixed pixels in curve records. The automatic image processing technology cannot accurately fill in the missing parts, and the automatic processing technology based on image analysis technology will affect the accuracy of water level curves. Therefore, it is particularly important to extract water level curves based on the characteristics of historical tide level images and digitize them. Summary of the Invention

[0006] To this end, the present application provides a method, apparatus, and computer device for digitizing historical paper tide records, to solve the problems in the prior art that paper tide records cannot be processed in batches and the accuracy of the processed water level curve is relatively low.

[0007] To achieve the above object, the present application provides the following technical solutions:

[0008] In a first aspect, a method for digitizing historical paper tide records includes:

[0009] Step 1: Convert the historical paper tide record into an electronic format to generate a tide table image;

[0010] Step 2: Geometrically calibrate the tide table image according to the raster data geometric correction method;

[0011] Step 3: Based on the geometrically calibrated tide table image, establish a vector line layer, and collect the tide curve in the tide table image by interactive digitization;

[0012] Step 4: Adjust the ordinate of the tide curve and splice it to obtain a complete tide curve;

[0013] Step 5: Select some tide level record arrays and high and low tide arrays at integral time points in the paper tide record to accurately correct the complete tide curve to obtain tide level curve data consistent with the actual recorded values;

[0014] Step 6: Evaluate the accuracy of the tide level curve data according to the remaining tide level record arrays at integral time points in the paper tide record;

[0015] Step 7: Obtain an equal-time-interval water level data sequence from the evaluated tide level curve data to obtain a digitized tide data set.

[0016] Preferably, in step 2, when geometrically calibrating the tide table image, multiple control points need to be selected on each tide table image, and the multiple control points need to be evenly distributed throughout the tide table image.

[0017] Preferably, if the tide table image is deformed, control points need to be encrypted in the deformed area.

[0018] Preferably, in step 2, the raster data geometric correction method uses a quadratic polynomial correction method.

[0019] Preferably, in step 4, when adjusting the ordinate of the tide curve, the tide curve is translated vertically by multiple integer multiples of the longitudinal coordinate unit of the paper tide record according to the law of the tide curve and the water level value.

[0020] Preferably, step 6 specifically includes: comparing the remaining hourly water level record arrays in the paper tide record table with the corresponding digitized water level record values at the same hourly moments to obtain the average error and the error interval distribution, and evaluating the accuracy of the tide curve data according to the average error and the error interval distribution.

[0021] Preferably, in step 7, when obtaining the equal-time-interval water level data, the equal-time-interval water level data at the minute level, hourly moments, and other time resolutions are obtained according to different time resolutions.

[0022] In a second aspect, a digitizing device for a historical paper tide record table includes:

[0023] An electronic processing module, configured to convert the historical paper tide record table into an electronic format and generate a tide table image;

[0024] A geometric calibration module, configured to perform geometric calibration on the tide table image according to the raster data geometric calibration method;

[0025] A tide curve extraction module, configured to establish a vector line layer based on the geometrically calibrated tide table image and collect the tide curve in the tide table image by means of interactive digitization;

[0026] A tide curve integration module, configured to adjust the ordinate of the tide curve and splice it to obtain a complete tide curve;

[0027] A tide curve correction module, configured to select some hourly water level record arrays and high and low tide arrays in the paper tide record table to accurately correct the complete tide curve to obtain tide curve data consistent with the actual record values;

[0028] An accuracy evaluation module, configured to evaluate the accuracy of the tide curve data according to the remaining hourly water level record arrays in the paper tide record table;

[0029] A data acquisition module, configured to obtain an equal-time-interval water level data sequence from the evaluated tide curve data to obtain a digitized tide data set.

[0030] In a third aspect, a computer device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of a digitizing method for a historical paper tide record table are implemented.

[0031] In a fourth aspect, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of a digitizing method for a historical paper tide record table are implemented.

[0032] Compared with the prior art, the present application has at least the following beneficial effects:

[0033] The present application provides a method, device, and computer equipment for digitizing historical paper tide records, which convert historical paper tide records into an electronic format to generate tide table images; perform geometric calibration on the tide table images according to the raster data geometric calibration method; based on the geometrically calibrated tide table images, establish a vector line layer, and collect the tide curves in the tide table images through an interactive digitization method; adjust the ordinate of the tide curves and splice them to obtain a complete tide curve; select some hourly tide level record arrays and high and low tide arrays in the paper tide records to accurately calibrate the complete tide curve to obtain tide level curve data consistent with the actual recorded values; evaluate the accuracy of the tide level curve data according to the remaining hourly tide level record arrays in the paper tide records; obtain water level data at equal time intervals from the evaluated tide level curve data to obtain a digitized tide data set. The method for digitizing historical paper tide records provided by the present application can batch process historical paper tide records, and can automatically fill in the missing parts, improving the accuracy of the tide level curve data and laying a digital foundation for tide record information sharing and numerical analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more intuitively illustrate the prior art and the present application, exemplary drawings are given below. It should be understood that the specific shapes and structures shown in the drawings generally should not be regarded as limiting conditions when implementing the present application; for example, those skilled in the art are capable of making routine adjustments or further optimizations to the addition / deletion / attribution division of certain units (components), specific shapes, positional relationships, connection methods, dimensional proportional relationships, etc. based on the technical concepts disclosed in the present application and the exemplary drawings.

[0035] Figure 1 It is a basic flowchart of a method for digitizing historical paper tide records provided in Embodiment 1 of the present application;

[0036] Figure 2 It is a flowchart of a method for digitizing historical paper tide records provided in Embodiment 1 of the present application;

[0037] Figure 3 It is a paper water level record diagram (partial schematic diagram) provided in Embodiment 1 of the present application, where, Figure 3 a is a curve grid recording paper, Figure 3 b is a rectangular grid recording paper;

[0038] Figure 4 It is a water level curve diagram ( Figure 4 a) and a splicing diagram ( Figure 4 b) extracted from the tide table provided in Embodiment 1 of the present application;

[0039] Figure 5This is the digital water level map provided by the first embodiment of this application. Detailed implementation manners

[0040] The following further details this application through specific embodiments in conjunction with the accompanying drawings.

[0041] In the description of this application: Unless otherwise specified, "a plurality of" means two or more. Terms such as "first", "second", "third", etc. in this application are intended to distinguish the objects being referred to, and do not have special significance in terms of technical connotations (for example, they should not be understood as emphasizing importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0042] Terms such as "upper", "lower", "left", "right", "middle", etc. cited in this application are usually indications of the general relative position relationship for the convenience of intuitively understanding with reference to the accompanying drawings, and are not absolute limitations on the position relationship in the actual product.

[0043] Embodiment 1

[0044] Please refer to Figure 1 and Figure 2 , this embodiment provides a method for digitizing historical paper tide records, including:

[0045] S1: Convert the historical paper tide record into an electronic format to generate a tide table image;

[0046] Specifically, collect and organize paper tide records (including curve grid record paper and rectangular grid record paper, as shown in Figure 3 ) in units of tide gauge stations, sort them by date, and then scan the paper tide records, naming them according to the station and the tide record date for electronic storage and query.

[0047] S2: Geometrically calibrate the tide table image according to the raster data geometric correction method;

[0048] Specifically, the ordinate in the tide record table is the tide level value (the unit is usually: centimeter), the abscissa is the time t (the unit is: hour), and the ordinate is the tide level z (the unit is: centimeter). The grid of the tide record table has a main grid (with a thicker line type) and a secondary grid (with a thinner line type), and the control point coordinates are (t, z), where t is the time (the unit is: hour) and z is the tide level coordinate (the unit is: centimeter).

[0049] In this step, the raster data geometric correction method is used for geometric calibration of the tide table image. Multiple control points are selected for each tide table image, and the number of control points is not less than 16. The overall layout of the control points is distributed as evenly as possible in the entire tide table. The control points need to be encrypted on the deformed tide table. The tz geometric correction of the tide table adopts the quadratic polynomial correction method, and the error in the geometric correction is controlled within 2 pixels. The specific implementation tool can use remote sensing or GIS software platform. Taking the open source GIS software QGIS tool as an example, open the raster data geometric correction graphical interface, load the tide table image to be scanned, and enter the correction control point coordinates (t, z) in the tide table.

[0050] S3: Based on the geometrically calibrated tide table image, a vector line layer is established, and the tide curve in the tide table image is collected by interactive digitization;

[0051] Specifically, this step uses the GIS software platform to establish a vector line layer based on the geometrically calibrated tz image to store tidal curve data and adopts interactive digitized tidal curves. Taking the QGIS software system as an example, load the tidal table that has been geometrically corrected in the previous step, overlay the established vector line file, use the tidal table as the base map to interactively collect tidal curves, and save the vector line data. See the tidal curve extraction sample map for details. Figure 4 a.

[0052] S4: adjust the ordinate of the tidal curve and splice it to obtain a complete tidal curve;

[0053] Specifically, this step is mainly for the tidal record table with large tidal range, and the tidal curve is recorded in a cycle. Figure 3 For this type of tidal record table in b, it is necessary to translate the recorded tidal curve up and down by an integer multiple of the vertical coordinate unit of the tidal record paper according to the tidal curve law and water level value, complete the integration of the recorded curves on the tidal record paper, splice the tidal curves, and obtain the tidal curve corresponding to each tidal table. The integrated tidal curve is shown in Figure 4 b.

[0054] S5: Select the tide level record arrays and high and low tide arrays of some hourly moments in the paper tide record table to accurately calibrate the complete tide curve, and obtain tide level curve data consistent with the actual record values;

[0055] Specifically, step S4 completes the integration of the water level curve (i.e., the integration of the tidal curve). Since the water level coordinate z is a relative value, it needs to be further corrected in combination with the mark in the figure. i , z i), where i is the integral time point, and the high tide level (z_high), low tide level (z_low) and their corresponding times are also recorded.

[0056] In this step, about half of the water level records in the integral time point water level record array of this tidal record table and the high and low tide array are selected to accurately correct the integrated water level curve, and the tidal level curve data consistent with the actual recorded value is obtained. The correction method can be processed with reference to the vector data geometric correction steps and methods based on the GIS software platform. The digital water level data sample diagram is as Figure 5 shown.

[0057] S6: Evaluate the accuracy of the tidal level curve data according to the remaining integral time point tidal level record array in the paper tidal record table;

[0058] Specifically, the integral time point tidal level array not used for the water level correction in step S5 is used to evaluate the digital accuracy of the tidal curve.

[0059] In this step, the recorded values in the tidal table are compared with the corresponding integral time point water level recorded values after digitization to obtain the average error and the error interval distribution. The error statistics of the digital water level data results are listed in Table 1.

[0060] Table 1: Digital water level data accuracy evaluation table

[0061]

[0062] S7: Obtain the water level data sequence at equal time intervals from the evaluated tidal level curve data to obtain the digital tidal dataset.

[0063] Specifically, the ordinate of the water level curve is the water level recorded value z, and the abscissa is the time t. In this step, tidal data at the minute level, integral time points and other time resolutions (Δ_T, T is the time resolution, in hours h) can be extracted according to different time resolutions.

[0064] More specifically, grid lines at equal time intervals can be generated based on the GIS software platform and intersections with the tidal curve can be found. The abscissa of the intersection is the time t, and the ordinate is the water level value z of the tidal record table. Taking the QGIS software platform as an example for specific implementation, grid data (line elements) are created in the vector layer, the horizontal interval is the required time resolution (in hours, hour), and the vertical range only needs to cover the maximum and minimum values of the tidal record. Then the generated grid lines and the tidal curve are intersected, and the coordinates of the intersection points are exported as the digital water level dataset at equal time intervals. The digital water level sample diagram is shown in Figure 5 . In this embodiment, using the GIS spatial analysis method, theoretically, tidal datasets with any time resolution can be obtained.

[0065] A method for digitizing historical paper tide records provided in this embodiment scans the tide records table and then geometrically corrects the tide table using the principle of image geometric correction. Using the corrected tide table as the base map, an interactive vector data acquisition method is used to collect the tide curves and integrate the tide curves. Then, based on the hourly tide record array and the high and low tide levels and corresponding time arrays, fine correction processing is performed on the tide curve data, and the accuracy of the extracted digitized tide data set is evaluated based on the record array in the tide table, thereby obtaining the digitized tide data set.

[0066] A method for digitizing historical paper tide records provided in this embodiment can batch process historical paper tide records tables, and can automatically fill in the missing parts, improving the accuracy of the tide level curve data and laying a digital foundation for the sharing and numerical analysis of tide record information.

[0067] Embodiment 2

[0068] This embodiment provides a device for digitizing historical paper tide records, including:

[0069] An electronic processing module for converting the historical paper tide records table into an electronic format to generate a tide table image;

[0070] A geometric calibration module for geometrically calibrating the tide table image according to the raster data geometric correction method;

[0071] A tide curve extraction module for establishing a vector line layer based on the geometrically calibrated tide table image and collecting the tide curves in the tide table image by an interactive digitization method;

[0072] A tide curve integration module for adjusting the ordinate of the tide curve and splicing it to obtain a complete tide curve;

[0073] A tide curve correction module for selecting part of the hourly tide level record array and the high and low tide arrays in the paper tide records table to precisely correct the complete tide curve to obtain tide level curve data consistent with the actual recorded values;

[0074] An accuracy evaluation module for evaluating the accuracy of the tide level curve data according to the remaining hourly tide level record array in the paper tide records table;

[0075] A data acquisition module for obtaining an equal-time interval water level data sequence from the evaluated tide level curve data to obtain a digitized tide data set.

[0076] For the specific implementation content of each module in a device for digitizing historical paper tide records, reference can be made to the limitations on a method for digitizing historical paper tide records in the above text, which will not be elaborated here.

[0077] Embodiment III

[0078] This embodiment provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of a method for digitizing a historical paper tide record form are implemented.

[0079] Embodiment IV

[0080] This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of a method for digitizing a historical paper tide record form are implemented.

[0081] The technical features of the above embodiments can be combined arbitrarily (as long as there is no contradiction in the combination of these technical features). For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described; these embodiments not explicitly written out should also be regarded as within the scope described in this specification.

Claims

1. A method for digitizing a historical paper tidal record table, characterized in that: include: Step 1: Convert the historical paper tide record table into electronic format to generate tide table image; Step 2: geometrically calibrating the tide table image according to a raster data geometric correction method; Step 3: Based on the tidal table image after geometric calibration, a vector line layer is established, and the tidal curve in the tidal table image is collected by interactive digitization; Step 4: adjusting the ordinate of the tidal curve and splicing them to obtain a complete tidal curve; Step 5: Select the tide level record arrays and high and low tide arrays of some hourly moments in the paper tide record table to accurately calibrate the complete tide curve to obtain tide level curve data consistent with the actual record values; Step 6: Evaluate the accuracy of the tide curve data according to the remaining tide record array at the hour in the paper tide record table; Step 7: Obtain a water level data sequence with equal time intervals from the evaluated tide curve data to obtain a digital tide data set.

2. The method for digitizing a historical paper tidal record sheet according to claim 1, characterized in that: In step 2, when geometrically calibrating the tide table image, it is necessary to select multiple control points on each tide table image, and the multiple control points need to be evenly distributed in the entire tide table image.

3. The method for digitizing a historical paper tidal record sheet according to claim 2, characterized in that: If the tide table image is deformed, it is necessary to encrypt the control points in the deformed area.

4. The method for digitizing a historical paper tidal record sheet according to claim 1, characterized in that: In step 2, the grid data geometric correction method adopts a quadratic polynomial correction method.

5. The method for digitizing a historical paper tidal record sheet according to claim 1, characterized in that: In step 4, when adjusting the vertical coordinate of the tidal curve, the tidal curve is translated up and down by multiple integer multiples of the vertical coordinate unit of the paper tidal record table according to the tidal curve law and the water level value.

6. The method for digitizing a historical paper tidal record sheet according to claim 1, characterized in that: Step 6 specifically includes: comparing the remaining tide level record array at the hour in the paper tide record table with the water level record value at the corresponding hour after digitization, obtaining the average error and error interval distribution, and evaluating the accuracy of the tide curve data based on the average error and error interval distribution.

7. The method for digitizing a historical paper tidal record sheet according to claim 1, characterized in that: In step 7, when acquiring water level data at equal time intervals, water level data at equal time intervals of minute level, hourly level, and other time resolutions are acquired according to different time resolutions.

8. A device for digitizing historical paper tidal records, characterized in that: include: An electronic processing module is used to convert historical paper tide record tables into electronic format and generate tide table images; A geometric calibration module, used for geometrically calibrating the tide table image according to a raster data geometric correction method; A tidal curve extraction module is used to establish a vector line layer based on the tidal table image after geometric calibration, and collect the tidal curve in the tidal table image through interactive digitization; A tidal curve integration module, used for adjusting the ordinate of the tidal curve and splicing it to obtain a complete tidal curve; A tide curve correction module is used to select tide level record arrays and high and low tide arrays at some hourly moments in a paper tide record table to accurately correct the complete tide curve, so as to obtain tide level curve data consistent with the actual record value; An accuracy evaluation module, used for evaluating the accuracy of the tide curve data according to the remaining tide record array at the hour in the paper tide record table; The data acquisition module is used to acquire a water level data sequence with equal time intervals from the evaluated tide curve data to obtain a digital tide data set.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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