Method for automatic conversion of s-57 and s-101 electronic chart data

Abstract

This invention relates to an automatic conversion method for S-57 and S-101 electronic nautical chart data, belonging to the field of marine surveying technology. The method involves reading and parsing S-57 nautical chart data, initializing a conversion rule engine, converting topological geometric units in S-57 into geometric simplexes in S-101, converting S-57 landmarks and their attributes into S-101 features and their attributes according to conversion rules, and handling special cases such as multi-valued attributes, tidal current tables, surrounding depths, complex features, and light arc merging; converting S-57 metadata into S-101 metadata; and finally exporting S-101 data in a preset order. This invention, by constructing a comprehensive conversion rule engine, supports the conversion of complex features and attributes, overcoming the shortcomings of existing conversion tools in terms of information completeness, accuracy, and applicability, significantly improving conversion efficiency and accuracy. It has already been applied in the chart production sector in my country.

Description

Technical Field

[0001] This invention belongs to the field of marine surveying and mapping technology, and in particular to an automatic conversion method for S-57 and S-101 electronic nautical chart data. Background Technology

[0002] Currently, the International Hydrographic Organization (IHO) is accelerating the implementation and application of the new standard, "General Hydrographic Data Model" (S-100). Based on this standard, various marine geographic information product specifications (collectively referred to as the S-100 series standards) can be formulated. The plan is to begin implementing the next-generation electronic nautical chart product specification (S-101) in 2026, thus propelling the S-100 series standards into the practical application stage. The emergence of the S-100 standard provides a unified framework for the representation of marine spatiotemporal information and intelligent navigation applications, and it will soon replace the current international standard, "Digital Hydrographic Data Transmission Standard" (S-57).

[0003] S-101 is the product specification that IHO prioritized for development in the S-100 series of standards, and it is also currently the most complex. Considering the large amount of S-57 nautical chart data already available both domestically and internationally, an S-101 dataset can be quickly constructed through data conversion. The S-57 standard defines real-world entities as objects, employing a "chain-node" topology: nodes and edges are used as topological geometric units, with each object referencing several topological geometric units; the spatial geometry of point objects is represented by isolated nodes or connected nodes; the spatial geometry of line objects is represented by a set of edges and connected nodes, with edges having a connecting node as their starting and ending point; the spatial geometry of area objects is represented by an outer loop and several inner loops, with each loop consisting of several edges connected end-to-end; point objects of the same batch of depth can be further linked to form a "set" relationship, creating multi-point objects.

[0004] Compared to the S-57 standard, S-101 product data differs significantly in both classification coding and spatial geometry: (1) S-101 defines real-world entities as features and allows the use of complex features and complex attributes, providing more flexible and powerful representation capabilities. Through complex features, complex objective phenomena such as routes, archipelagos, and bridges can be expressed; through complex attributes, seven simple attributes such as "Boolean, enumeration, integer, real, text, date, and time" can be combined, and further nesting of complex attributes is also supported to form higher-level complex attributes.

[0005] (2) S-101 adopts a more rigorous spatial model, using spatial types such as points, multiple points, curves, composite curves, loops, and surfaces as topological geometric units. Each element references several topological geometric units; the spatial geometry of point elements is represented by points; the spatial geometry of water depth groups is represented by multiple points; the spatial geometry of line elements is represented by composite curves, and the composite curves must have a point as their starting point and ending point; the spatial geometry of surface elements is represented by one outer loop and several inner loops, and each loop is a curve or composite curve that is connected end to end.

[0006] From a data model perspective, the S-57 and S-101 electronic nautical charts differ significantly in spatial geometry, classification coding, and element composition. Currently, both domestic and international organizations have conducted some conversion experiments or engineering practices, but these all involve some degree of information loss. The main problem lies in the lack of a complete conversion process and specialized processing techniques.

[0007] The paper "Research on IHO S-101 Electronic Nautical Chart Data Conversion Engine" (by Li Haisong) discloses a data conversion method between the S-57 and S-101 standards. This method is based on the existing feature attribute conversion rules (XML files) of Caris. It realizes the automatic conversion of S-57 to S-101 electronic nautical charts through modules such as S-57 file reading, data conversion, and S-101 data encapsulation. The results have been verified on a third-party software system. However, this achievement does not take into account complex features, complex attributes, and information types, and the rules it adopts are too simple, such as lacking spatial judgment operators. Therefore, its conversion accuracy still has a lot of room for improvement and has not been truly put into application. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and propose an automatic conversion method for S-57 and S-101 electronic nautical chart data. By constructing a feature-rich and rule-based conversion engine and performing refined processing on various special cases in the conversion process, efficient, accurate and complete data conversion can be achieved, thereby promoting the implementation and application of the S-101 standard.

[0009] The technical problem solved by this invention is achieved through the following technical solution: An automatic conversion method for S-57 and S-101 electronic nautical chart data includes the following steps: Step 1: Read and parse S-57 nautical chart data, and initialize the S-57 to S-101 conversion rule engine; Step 2: Convert the topological geometric units in the S-57 data into geometric simplexes of S-101, and convert the location quality attributes into spatial quality information types, and establish the reference relationship between features and information types; Step 3: Convert S-57 objects and their attributes into S-101 features and their attributes according to the conversion rules, including special processing of multi-valued attributes, trend table information, surrounding depth, complex features and light arc features; Step 4: Convert the DSID and DSSI metadata of S-57 to DSID and DSSI of S-101; Step 5: Export the S-101 nautical chart data in the order of metadata, information type, point, multi-point, curve, combined curve, surface, and element.

[0010] Furthermore, the processing of multi-valued attributes in step 3 includes: splitting the attribute values ​​separated by commas in S-57 into sub-attributes of complex attributes in S-101; filtering null-valued attributes and retaining only valid attribute values.

[0011] Furthermore, the processing of the trend table information in step 3 includes: splitting the TS_TSP attribute of the TS_PAD object in S-57 into corresponding parent and child attributes in S-101 according to 13 time periods.

[0012] Furthermore, the processing of surrounding depth in step 3 includes: assigning a value to the "surrounding water depth" attribute for four types of elements: obstacles, reefs, shipwrecks, and aquaculture areas, based on the minimum water depth value of their respective depth zones.

[0013] Furthermore, the processing of complex elements in step 3 includes: creating S-101 aggregated elements based on the set element objects in S-57, and establishing aggregated relationships between elements; if the same object appears in both the set and the association relationship, no conversion is performed.

[0014] Furthermore, the processing of the lamp arc elements in step 3 includes: merging multiple lamp arc objects with common points in S-57 into a single lamp arc element S-101, and merging their lamp arc attributes.

[0015] Furthermore, the transformation rule engine in step 1 adopts an XML structure and supports condition judgment, feature mapping, attribute mapping, spatial relationship judgment, complex feature creation, and relationship setting.

[0016] Furthermore, the topological geometric unit transformation in step 2 includes: converting isolated nodes and connected nodes into points; converting edges into curves; combining multiple edges into composite curves; and converting loop structures into surfaces.

[0017] Furthermore, the S-101 data exported in step 5 supports batch processing and is suitable for nautical chart data files larger than 5MB.

[0018] The advantages and positive effects of this invention are: This invention is rationally designed. Based on a thorough analysis of the differences between S-57 and S-101 electronic chart codes, it constructs richer and more comprehensive conversion rules and engines. It also provides processing methods for special cases such as multi-value attribute splitting, surrounding depth calculation, complex feature creation, and light arc feature merging. The resulting conversion software surpasses similar software at home and abroad in terms of efficiency and accuracy, and has been practically applied in my country's chart production departments. Attached Figure Description

[0019] Figure 1 Flowchart of the automatic conversion method for S-57 to S-101 electronic nautical chart data; Figure 2 A schematic diagram comparing data records before and after topological geometric unit transformation; Figure 3 A schematic diagram illustrating the effect of converting an S-57 object to an S-101 element. Figure 4 A comparative diagram showing the effect of converting S-57's NATQUA attribute to S-101 when it contains null values; Figure 5 The TS_PAD current flow surface plate marker of the S-57 before conversion; Figure 6 This refers to the Tidal Stream Panel Data elements of the S-101 after conversion; Figure 7 The S-57 object (Wreck) before conversion and its Value of sounding attribute; Figure 8 The transformed S-101 feature (Wreck) and its Surrounding Depth attribute; Figure 9 This refers to the aggregated elements and relationships after conversion to S-101; Figure 10 The lamp arc element to be converted to S-101 contains multiple lamp arc attributes; Figure 11 Comparison of S-57 data before conversion with S-101 data after conversion; Figure 12 This diagram illustrates the comparison between the conversion effects of the dKart conversion tool and this method. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings.

[0021] An automatic conversion method for S-57 and S-101 electronic nautical chart data, such as Figure 1 As shown, it includes the following steps: Step 1: Read and parse S-57 nautical chart data, and initialize the S-57 to S-101 conversion rule engine.

[0022] The S-57 data is loaded and parsed using the ISO 8211 library. An XML structure is used as the carrier for S-57 to S-101 conversion rules, implementing different conversion rules through elements such as conditional syntax, feature syntax, and attribute syntax. The table below lists the syntax included in the conversion rule engine. Compared to existing nautical chart conversion rules, it adds syntax for hierarchical relationship judgment (ObjectIsAChildTo, FeatureHasComponent), spatial relationship judgment (GeometryIsWithin and GeometryShareSpatial), complex feature creation (CreateCollectionFeature), and relationship creation (SetRelationshipCode), which can meet more complex conditional judgment and conversion processing needs.

[0023] Step 2: Topological geometric unit transformation.

[0024] By assigning coordinates to points, the conversion from isolated nodes and connected nodes to points is realized; by assigning coordinates to a set of points, the conversion from isolated nodes and edges to multiple points and curves is realized; and by referencing curves, the conversion from composite curves to surfaces is realized.

[0025] like Figure 2 As shown: Before the conversion, the physical records of isolated nodes (only 1 point) of S-57 use vector record identifier field and 2-D coordinate field to record coordinate information; after the conversion, the physical records of points of S-101 use point record identifier field and 2-D integer coordinate tuple field.

[0026] Before the conversion, isolated nodes (multiple points) of S-57 were recorded in the physical storage record using a Vector Record Identifier field and a 3-D Coordinate field to record coordinate information; after the conversion, points of S-101 were recorded in the physical storage record using a Multi Point Record Identifier field and a 3-D Integer Coordinate Tuple field.

[0027] Before the conversion, the physical records of the connection nodes of S-57 used vector record identifier field and 2-D coordinate field to record coordinate information; after the conversion, the physical records of points of S-101 used point record identifier field and 2-D integer coordinate tuple field.

[0028] Step 3: S-57 Object Conversion. First, for non-special cases, the conversion from S-57 objects (and attributes) to S-101 features (and attributes) is performed according to the conversion rules; then, special attributes and special features are converted; finally, the topological geometric units are further processed according to the spatial type.

[0029] like Figure 3 The image shows a comparison of the effects before and after the conversion under normal circumstances. Under normal circumstances, after S-57 landmarks are converted into S-101 elements, the original S-57 landmark types and the new S-101 element types can be matched one-to-one. For example, landmarks such as waterways, lighthouses, fog signals, and radar / radio signals are converted according to the conversion rules. A comparison reveals that the geometry and graphics are basically the same before and after the conversion.

[0030] Special cases of transformation include: multi-value attribute splitting, power flow table information transformation, surrounding depth calculation, complex feature creation, and light arc feature merging, as detailed below: 1. Multi-valued attribute splitting The table below shows the object attributes with multiple values ​​in the S-57 standard and their corresponding S-101 feature attributes.

[0031] Taking the NATSUR attribute of the S-57 seabed feature as an example, if its value is (4,1), then in S-101 it should be recorded as natureOfSurface=4 and natureOfSurface=1. Therefore, in the conversion rule, a split constraint needs to be set for this rule and named "S-57 attribute_to_S-101 attribute", such as "NATSUR_to_natureOfSurface". It then checks if there are multiple values. If so, the attribute value is split according to the comma, and then an equal number of natureOfSurface attributes are created and assigned values ​​based on the number of split attribute values. If not, the split rule is not followed, and values ​​are assigned directly.

[0032] like Figure 4 As shown, null values ​​also require special handling. For example, the NATQUA attribute value (6,1,) of the S-57 seabed area marker should be recorded as natureOfSurfaceQualifyingTerms=6 and natureOfSurfaceQualifyingTerms=1 in S-101. The last value is null and can be left unrecorded.

[0033] 2. Trend chart information conversion like Figure 5 As shown, the tidal flow panel (TS_PAD) marker in S-57 only defines one TS_TSP attribute to record tidal flow information, which corresponds to multiple complex attributes in the "Tidal flow panel data" element in S-101. The two have significant differences in structure.

[0034] like Figure 6 As shown, S-57 uses a single string message for representation, while S-101 needs to split the message into 13 parent attributes according to -6 o'clock, -5 o'clock, -4 o'clock, -3 o'clock, -2 o'clock, -1 o'clock, 0 o'clock, 1 o'clock, 2 o'clock, 3 o'clock, 4 o'clock, 5 o'clock, and 6 o'clock. Each parent attribute records sub-attribute information such as azimuth and speed.

[0035] Relevant information from 13 time periods is extracted sequentially, and corresponding parent and child attributes are created in the S-101 information.

[0036] 3. Surrounding depth calculation The "surrounding depth" attribute in S-101 is a new attribute and is a conditionally mandatory attribute, applicable to underwater hazards at unknown depths: when the "value of sounding" attribute is empty, the surrounding depth must be assigned a value. There are four types of features in S-101 that include the surrounding depth attribute: Marine Farm / Culture, Obstruction, Underwater / Awash Rock, and Wreck.

[0037] The conversion process of the surrounding depth attribute mainly consists of two steps: ① Calculate the spatial inclusion relationship based on the spatial geometric position of elements such as Marine Farm and Wreck to obtain the depth zone where the element is located; ② Create the surrounding water depth in the Marine Farm and Wreck element attributes and assign the minimum depth range value of the depth zone to the surrounding water depth.

[0038] like Figure 7 , Figure 8 As shown, the Wreck feature attribute "Value of sounding" in S-57 is empty. After conversion to S-101, the corresponding Wreck feature attribute "Value of sounding" is still empty, but the Surrounding Depth must be assigned a value of 30.0m, where 30.0m is the minimum depth range value assigned to the surrounding water depth.

[0039] 4. Creation of Complex Elements S-101 introduced a new feature type called "Complex Feature". Complex features and simple features are linked through the "Feature Referencing Feature Field" (FASC) record, allowing for a multi-layered and multi-faceted description of an object in the real geographic world. The table below shows the complex feature types defined in S-101 and their corresponding linking names:

[0040] S-57 aggregation is a relationship, entirely recorded in the "set" (C_AGGR) meta-identity information. Therefore, the transformation requires the use of complex feature aggregation relationship transformation rules, and the main process includes: ① Determine the new S-101 aggregation element based on the object names recorded in C_AGGR. When there are multiple objects, each object needs to be considered. For example, if the objects include two objects, DWRTCL and DWRTPT, a new DeepWaterRoute aggregation element should be created; if the objects include 12 types of objects, such as DWRTCL, DWRTPT, TSSBND, TSSLPT, ISTZNE, PRCARE, TSELNE, TSEZNE, TSSBND, TSSCRS, TSSLPT, and TSSRON, a new TrafficSeparationScheme aggregation element should be created.

[0041] ② The first iteration iterates through all C_AGGR meta-objects in S-57. Each C_AGGR meta-object corresponds to a cluster feature in S-101. Based on the method described in ①, the cluster feature type corresponding to the C_AGGR meta-object is determined, and an S-101 cluster feature is created accordingly, such as creating a DeepWaterRoute cluster feature. The newly created cluster feature does not yet reference any associated S-101 simple features. The newly created cluster feature is saved to a temporary array.

[0042] ③ The second iteration traverses all C_AGGR meta-objects in S-57, processes the objects contained in each C_AGGR, converts the contained objects into S-101 simple features, and records the simple features in the newly created aggregated features in ②. The specific processing method is as follows: Obtain the FFPT attribute value of each C_AGGR meta-object. Through the FFPT attribute value, the S-57 objects contained in the C_AGGR meta-object can be obtained. Determine whether the contained objects are also contained in the C_ASSO meta-object. If they are contained in C_ASSO, skip processing. If they are not contained in C_ASSO, use the non-special case conversion method described in step 3 to convert the contained S-57 objects into S-101 features. After conversion, record the FOID of the new S-101 into the FASC field of the aggregated features created in ②. At this point, the complex feature conversion construction is completed. Figure 9 The diagram shows the aggregation elements and relationships of the S-101 lane separation system.

[0043] 5. Merging of lamp arc elements In S-57, a sector-shaped or ring-shaped light arc is recorded as multiple objects, and each object's attribute records a segment of the light arc. That is, these objects have the same point geometric simplex, but different attributes. In S-101, although sector-shaped and ring-shaped light arcs are also defined, a light arc is recorded using only one feature, meaning that the feature includes multiple light arc attributes.

[0044] Therefore, during the conversion, the arc feature merging rule needs to be used to merge multiple arc features in S-57 into a single arc feature in S-101, which contains complex attributes of multiple sector characteristics. The specific process is as follows: ① Convert the S-57 lamp arc object one-to-one into S-101 lamp arc elements; the converted S-101 lamp arc elements have redundant elements, which will be merged in subsequent steps and then the redundant elements will be deleted. ② Obtain S-101 lamp arc elements with the same geometric position. Specific steps: Traverse all S-101 lamp arc elements converted in step ①, determine whether the geometric positions of the S-101 lamp arc elements are the same. If the geometric positions are the same, it means that these S-101 lamp arc elements need to be merged. Then record the S-101 lamp arc elements with the same geometric position into a list. ③ Merge the Sector Characteristics complex attributes of S-101 lamp arc features with the same geometric location. The specific steps are as follows: According to the record order of the list of identical locations formed in step ②, take the first S-101 lamp arc feature in the list as the merging subject, and copy the Sector Characteristics complex attributes of other lamp arc features in the list one by one into the attributes of the merging subject; after the merging is completed, the S-101 lamp arc features that serve as the merging subject will form parallel SectorCharacteristics complex attributes. The number of Sector Characteristics complex attributes is equal to the number of features contained in the list formed in step ②. ④ Save the S-101 light arc feature as the main element to be merged, and delete the other light arc features in the list. At this point, the conversion of a light arc feature containing complete Sector Characteristics attributes is complete. Figure 10 This refers to the S-101 lamp arc element and its three Sector Characteristics attributes after the merger is completed.

[0045] Step 4: S-57 Metadata Conversion. Convert the DSID and DSSI metadata from S-57 to the corresponding DSID and DSSI metadata in S-101. The field values ​​of each field in the S-101 metadata can be obtained by assigning values ​​to the relevant fields in the S-57 metadata. For example... Figure 11The diagram shows a comparison of the S-57 metadata and the S-101 metadata before and after the conversion. The main features include: assigning the Edition Number of the S-57 metadata to the Dataset Edition field of the S-101 metadata; assigning the Product Specification Edition Number of the S-57 metadata to the Product Edition of the S-101 metadata; and assigning the Application Profile Identification of the S-57 metadata to the Application Profile of the S-101 metadata.

[0046] Step 5: Export S-101 nautical chart data. Store the data in the following order: metadata, information type, point geometric topology unit, multi-point geometric topology unit, curve geometric topology unit, combined curve geometric topology unit, surface geometric topology unit, and features.

[0047] In practice, extensive data testing was conducted, and the results were compared with those of mainstream international conversion software such as dKart. It is consistent with dKart in handling S-101 Chinese encoding and attribute value multiplicity, but superior to dKart in beacon and light arc conversion and handling data larger than 5MB. Figure 12 The image shows a comparison of the conversion effects of the Kart conversion tool and this method.

[0048] It should be emphasized that the embodiments described in this invention are illustrative rather than limiting. Therefore, this invention includes, but is not limited to, the embodiments described in the specific implementation. Any other implementations derived by those skilled in the art based on the technical solutions of this invention are also within the scope of protection of this invention.

Claims

1. An automatic conversion method for S-57 and S-101 electronic nautical chart data, characterized in that, Includes the following steps: Step 1: Read and parse S-57 nautical chart data, and initialize the S-57 to S-101 conversion rule engine; Step 2: Convert the topological geometric units in the S-57 data into geometric simplexes of S-101, and convert the location quality attributes into spatial quality information types, establishing a reference relationship between features and information types; Step 3: Convert S-57 objects and their attributes into S-101 features and their attributes according to the conversion rules, including special processing of multi-valued attributes, trend table information, surrounding depth, complex features and light arc features; Step 4: Convert the DSID and DSSI metadata of S-57 to DSID and DSSI of S-101; Step 5: Export the S-101 nautical chart data in the order of metadata, information type, point, multi-point, curve, combined curve, surface, and element.

2. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The processing of multi-valued attributes in step 3 includes: splitting the attribute values ​​separated by commas in S-57 into sub-attributes of complex attributes in S-101; filtering null-valued attributes and retaining only valid attribute values.

3. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The processing of the trend table information in step 3 includes: splitting the TS_TSP attribute of the TS_PAD object in S-57 into the corresponding parent and child attributes in S-101 according to 13 time periods.

4. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The processing of surrounding depth in step 3 includes: assigning values ​​to the surrounding water depth attributes of four types of elements, namely obstacles, reefs, shipwrecks, and aquaculture areas, based on the minimum water depth value of their respective depth zones.

5. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The processing of complex elements in step 3 includes: creating aggregated elements S-101 based on the set element objects in S-57, and establishing aggregated relationships between elements; if the same object appears in both the set and the association relationship, no conversion is performed.

6. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The processing of the lamp arc elements in step 3 includes: merging multiple lamp arc objects with common points in S-57 into a single lamp arc element S-101, and merging their lamp arc attributes.

7. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The transformation rule engine in step 1 adopts an XML structure and supports condition judgment, feature mapping, attribute mapping, spatial relationship judgment, complex feature creation, and relationship setting.

8. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The topological geometric unit transformation in step 2 includes: converting isolated nodes and connected nodes into points; converting edges into curves; combining multiple edges into composite curves; and converting loop structures into surfaces.

9. The automatic conversion method for S-57 and S-101 electronic nautical chart data according to claim 1, characterized in that, The S-101 data exported in step 5 supports batch processing and is suitable for nautical chart data files larger than 5MB.

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