EncDotNet.S100.Datasets.S57 0.18.0

EncDotNet.S100.Datasets.S57

Reader and S-101 translator for IHO S-57 Electronic Navigational Chart (ENC) datasets.

Overview

This library reads S-57 (Edition 3.1) ENC base cells via the EncDotNet.S57 NuGet package (itself layered on top of EncDotNet.Iso8211) and translates the parsed records into the S-101 in-memory document model so the existing S-100 Part 9A Lua portrayal pipeline (provided by EncDotNet.S100.Datasets.S101) can render them. This is not an S-52 implementation — symbology is whatever the S-101 portrayal catalogue produces when fed the translated data.

Mappings follow the IHO S-57 to S-101 Conversion Guidance (S-101PT6 INF02A, draft 2021).

Key types:

• S57Dataset — entry point; opens a .000 file and exposes the parsed EncDotNet.S57.S57Document from the upstream package, plus a static IsS57File(path) discriminator used by EncDotNet.S100.Datasets.Pipelines to disambiguate .000 files that could otherwise be S-101.
• S57ToS101Translator — translates an S57Document (package type) into an S101Document by remapping object/attribute codes, exploding multi-point soundings, synthesising the information complex attribute from textual fields, and converting nodes/edges/area-rings into S-101 spatial primitives.
• S57S101Mapping — embedded code-mapping table sourced from IHO's S-57 → S-101 conversion guidance.
• S101AllowedEnumValues — lazy-loaded helper that consults the bundled S-101 Feature Catalogue to drop emitted enumerated attribute values that aren't permitted by the destination FC binding.

Translation behaviour

Limitations

• Base cells only. Update files (.001, .002, …) are not applied; the reader rejects them with a clear error.
• Breadth-first feature coverage. Most common feature classes map to S-101 acronyms; uncommon classes pass through unmapped and may not portray.
• Listed-value remapping is best-effort. Some S-57 enumerated attribute values have different numeric codes in S-101; values that aren't permitted by the destination S-101 FC binding are silently dropped.
• Complex-attribute synthesis is minimal. Sector lights and similar features that require S-101 nested complex attributes may not portray correctly.
• information is emitted directly on the feature (per the "generally" path in the conversion guidance) rather than via a separate NauticalInformation information type with an Additional Information association.

Validation

S57DatasetProcessor.Validate() runs validation in two phases:

1. Pre-translation — S57PreTranslationRules.Default checks the raw EncDotNet.S57.S57Document for things that don't survive translation (DSID / DSPM presence and a positive compilation scale; the presence of an M_COVR meta-feature).
2. Post-translation — the translated S-101 document is fed into S101DatasetRules.Default (the same pack that runs against native S-101 datasets) and the resulting findings are rebadged with the prefix S101-as-S57/ so the user can tell whether a problem originated in the raw S-57 input or in the translated S-101 projection.

Pre-translation rules shipped by S57PreTranslationRules.Default:

The two reports are concatenated by ConcatReports.Concat(pre, post, rebadgePrefix: "S101-as-S57/") in EncDotNet.S100.Datasets.Pipelines and cached on the processor.

Exchange-set integrity verification

S57ExchangeSetVerification integrity-verifies an S-57 / S-63 exchange set (a folder containing a CATALOG.031) and maps the result onto the same S-100 ExchangeSetVerificationResult model used for native S-100 exchange sets, so both products surface uniformly through the CLI (s100 validate) and any future viewer wiring.

using EncDotNet.S100.Datasets.S57;
using EncDotNet.S100.ExchangeSets;

ExchangeSetVerificationResult result =
    await S57ExchangeSetVerification.VerifyAsync("/path/to/s57set");

bool integrity = result.IntegrityVerified;   // no CRC mismatches / missing files
bool signed    = result.AllValid;            // strict: every file signature Ok

It is a deliberately thin adapter, not a shared interface: the upstream S-57 verifier (EncDotNet.S57 0.5.0+) is rooted at a directory path (CATALOG.031 plus the files it references), whereas the S-100 verifier is IAssetSource-based. Forcing both behind one interface would distort both, so only the result is mapped.

Mapping notes:

• Outcomes are mapped by name (S57VerificationOutcome → VerificationOutcome). The two enums are kept byte-identical; mapping by name means a future divergence fails loudly rather than silently mis-mapping.
• Both the signature dimension (Outcome) and the checksum dimension (ChecksumOutcome) are preserved independently.
• S-57 integrity uses a CRC-32 (the CATALOG.031 field), not the SHA-256 digest the S-100 model carries, so the per-file CRC values are surfaced through FileVerificationResult.Detail and ComputedSha256 is left null.
• The verdict semantics match S-100: NoChecksum / NotSigned are non-failing (an unsigned-but-intact set has IntegrityVerified == true but AllValid == false); only ChecksumMismatch / FileMissing / Error / invalid signatures fail integrity. This is identical to the upstream S-57 AllValid.
• Today the upstream S-57 verifier reports every file as NotSigned (S-63 signature verification is a seam); CRC checking is fully wired.

Exchange-set cell enumeration

S57ExchangeSetCatalog is the loading-side companion to the verification adapter above. It reads a CATALOG.031 (via EncDotNet.S57's S57CatalogReader) and groups the catalogued CATD files into renderable base cells, each with its in-set sequential updates and (optionally) its extent:

using EncDotNet.S100.Datasets.S57;

IReadOnlyList<S57ExchangeSetCell> cells =
    S57ExchangeSetCatalog.ReadBaseCells("/path/to/s57set");

foreach (S57ExchangeSetCell cell in cells)
{
    // cell.RelativePath          → "…/US5MA1BO.000" (platform-normalised)
    // cell.UpdateRelativePaths   → ["…/US5MA1BO.001", "…/US5MA1BO.002"]
    // cell.BoundingBox           → EPSG:4326 extent, or null
}

BoundingBox? union = S57ExchangeSetCatalog.UnionBoundingBox(cells);

Files are grouped by their 8-character cell name; the .000 file is the base and .001, .002, … are its updates in application order. Non-dataset entries (.TXT, certificates, the catalogue itself) are ignored, and update files with no matching base are skipped. The pure grouping logic is exposed as SelectBaseCells(S57Catalog) for unit testing without a real catalogue on disk. The viewer pairs this enumeration with a FileSystemAssetSource rooted at the exchange-set directory so each cell flows through the same S57DatasetProcessor code path as a single dropped .000 file (with its in-set updates folded in via S57Document.ApplyChanges before translation to S-101).

Like the verification adapter, this is a deliberately thin adapter over the directory-rooted S-57 model rather than a shared interface.

Usage

using EncDotNet.S100.Datasets.S57;
using EncDotNet.S100.Datasets.S101;

var s57 = S57Dataset.Open("US5NY16M.000");
var s101Document = new S57ToS101Translator().Translate(s57);
var dataset = S101Dataset.FromDocument(s101Document);
// Use the existing S-101 pipeline from here:
// S101LuaRuleExecutor, S101FeatureGeometryProvider, etc.

Installation

dotnet add package EncDotNet.S100.Datasets.S57