EncDotNet.S100 is a managed, cross-platform implementation of the IHO S-100 Universal Hydrographic Data Model for .NET. It provides:
- A set of reusable libraries for reading, portraying, rendering, and validating S-100 product data — from ISO 8211 ENC cells to HDF5 coverage grids to GML feature collections — behind a common pipeline abstraction.
- A cross-platform desktop viewer (Avalonia + Mapsui) that loads any combination of supported products from an exchange set or as loose files and renders them, time-aligned, on an interactive map.
- An optional MCP server that exposes loaded datasets to AI
agents (
list_datasets,describe_feature,sample_coverage,render_to_image).
The goal is to make S-100 data approachable for .NET developers and end users without requiring native dependencies, commercial S-52 assets, or platform-specific tooling. Everything runs on macOS, Windows, and Linux out of the box.
Every supported product ships a reader, a portrayal pipeline, and a normative validation rule pack.
| Standard | Subject | Encoding | Portrayal | Validation pack |
|---|---|---|---|---|
| S-101 | Electronic Navigational Charts | ISO 8211 | Lua (Part 9A) | ✅ |
| S-102 | Bathymetric Surfaces | HDF5 | Coverage (Lua) | ✅ |
| S-104 | Water Level Information | HDF5 | Coverage | ✅ |
| S-111 | Surface Currents | HDF5 | Arrow symbology | ✅ |
| S-122 | Marine Protected Areas | GML | XSLT | ✅ |
| S-124 | Navigational Warnings | GML | XSLT | ✅ |
| S-125 | Marine Aids to Navigation | GML | XSLT | ✅ |
| S-127 | Marine Resources & Services | GML | XSLT | ✅ |
| S-128 | Catalogue of Nautical Products | GML | XSLT | ✅ |
| S-129 | Under Keel Clearance Management | GML | XSLT | ✅ |
| S-131 | Marine Harbour Infrastructure | GML | Lua (Part 9A) | ✅ |
| S-201 | Aids to Navigation Information (IALA) | GML | XSLT | ✅ |
| S-411 | Sea Ice Information | GML | XSLT | ✅ |
| S-421 | Route Plans | GML | XSLT | ✅ |
| S-57 (legacy) | Electronic Navigational Charts (Ed 3.1) | ISO 8211 | via S-101 pipeline | ✅ (delegated) |
S-57 cells are translated to the in-memory S-101 model and rendered
through the S-101 portrayal pipeline; validation runs as two passes
with S-101 findings rebadged S101-as-S57/* so the user can tell
which layer of the pipeline a finding came from. This is a
best-effort path for viewing legacy chart collections; it is not
an S-52 implementation.
EncDotNet.S100.Viewer is a cross-platform desktop nautical chart
viewer built on Avalonia and
Mapsui. It loads any combination of the
supported products and renders them time-aligned over an
OpenStreetMap basemap. Headline features:
- Multi-product paint stack driven by the S-98 interoperability authority (display planes, within-plane priority, inter-product rules) rather than load order.
- Activity-bar panels for Datasets, Layer Stack, ECDIS Display Controls, Object Information (pick reports), Validation, and Settings — every panel can be docked, hidden, or rearranged, and the layout persists between sessions.
- Pick / Object Information for both vector and coverage
products, with FC-decoded attribute names, follow-the-
xlinkreference navigation, and an embedded time-series chart for fixed-station S-104 / S-111 observations. - ECDIS-style controls — display category, display planes, text groups, per-spec viewing groups, Day / Dusk / Night palettes, and mariner settings (safety contour, depth contours, four shades, simplified symbols, radar overlay).
- Global timeline for time-varying datasets (S-104, S-111, S-411).
- Validation panel with click-to-zoom, severity colouring, and an overlay marker layer.
- Live overlays through the dynamic-feature-source abstraction — an own-ship glyph with true-scale hull + arrowhead + CCRP cross at zoom, plus an AIS-target overlay (PR-D3) backed by the aisstream.io WebSocket service and rendered with a per-class palette using the same hull/arrowhead vocabulary.
- Optional MCP server (off by default) exposing the loaded datasets to AI agents.
See the viewer README for the full feature guide, and the per-product gallery below for what each product looks like in the viewer.
| Product | Screenshot |
|---|---|
| S-101 ENC |  |
| S-102 Bathymetry |  |
| S-104 Water Level |  |
| S-111 Surface Currents |  |
| S-122 Marine Protected Areas |  |
| S-124 Navigational Warnings |  |
| S-125 Marine AtoN |  |
| S-127 Marine Services |  |
| S-128 Catalogue |  |
| S-129 UKC |  |
| S-131 Marine Harbour |  |
| S-411 Sea Ice |  |
| S-421 Route Plan |  |
| S-57 (via S-101) |  |
For developers consuming EncDotNet.S100 directly, the solution is split into focused packages:
| Package | Description |
|---|---|
| EncDotNet.S100.Core | Pipeline abstractions (asset sources, HDF5, Lua, coverage + vector pipelines), the validation framework, and the dynamic-feature-source abstraction. |
| EncDotNet.S100.Features | Parser for S-100 Feature Catalogue XML files (ISO 19110 / S-100 Part 5). |
| EncDotNet.S100.ExchangeSets | Reader for S-100 Exchange Set catalogues and dataset/support file discovery. |
| EncDotNet.S100.Portrayals | Parser for S-100 Portrayal Catalogues (symbols, line styles, area fills, colour profiles, viewing groups). |
| EncDotNet.S100.Specifications | Bundles official feature and portrayal catalogues as embedded resources. |
| Package | Description |
|---|---|
| EncDotNet.S100.Hdf5.PureHdf | HDF5 reader implementation using PureHDF (fully managed, no native dependencies). |
| EncDotNet.S100.Scripting.MoonSharp | Lua 5.2 scripting engine using MoonSharp. |
| Package | Description |
|---|---|
| EncDotNet.S100.Datasets.S101 | S-101 ENC reader, Lua portrayal pipeline, validation pack (S101DatasetView façade + 10 rules). |
| EncDotNet.S100.Datasets.S102 | S-102 bathymetry reader, coverage pipeline, validation pack. |
| EncDotNet.S100.Datasets.S104 | S-104 water level reader, coverage pipeline, validation pack. |
| EncDotNet.S100.Datasets.S111 | S-111 surface currents reader, coverage pipeline (per-feature arrow symbology), validation pack. |
| EncDotNet.S100.Datasets.S122 | S-122 marine protected areas reader, XSLT portrayal pipeline, validation pack. |
| EncDotNet.S100.Datasets.S124 | S-124 navigational warnings reader, XSLT portrayal pipeline, validation pack. |
| EncDotNet.S100.Datasets.S125 | S-125 marine aids to navigation reader (with typed AtoN projection and xlink-resolved status), XSLT portrayal, validation pack. |
| EncDotNet.S100.Datasets.S127 | S-127 marine resources and services reader, XSLT portrayal pipeline, validation pack. |
| EncDotNet.S100.Datasets.S128 | S-128 catalogue of nautical products reader (with typed DataModel projection), XSLT portrayal, validation pack. |
| EncDotNet.S100.Datasets.S129 | S-129 under keel clearance reader, XSLT portrayal pipeline, validation pack. |
| EncDotNet.S100.Datasets.S131 | S-131 marine harbour infrastructure reader, Lua portrayal pipeline (GML+Lua hybrid), validation pack. |
| EncDotNet.S100.Datasets.S201 | S-201 aids to navigation information (IALA) reader, XSLT portrayal pipeline, typed AtoN inventory data model, validation pack. |
| EncDotNet.S100.Datasets.S411 | S-411 sea ice reader, XSLT portrayal pipeline, validation pack. |
| EncDotNet.S100.Datasets.S421 | S-421 route plan reader, XSLT portrayal pipeline, validation pack. |
| EncDotNet.S100.Datasets.S57 | Legacy S-57 ENC reader that translates to the in-memory S-101 model; pre-translation rules + delegation to the S-101 validation pack. |
| EncDotNet.S100.Datasets.Pipelines | Per-spec IDatasetProcessor implementations, the S-98 interoperability authority, the validation runner, and the ConcatReports rebadge helper used by S-57. |
| Package | Description |
|---|---|
| EncDotNet.S100.Renderers.Skia | Coverage and vector rendering to SkiaSharp bitmaps. |
| EncDotNet.S100.Renderers.Mapsui | Rendering of S-100 data into Mapsui map layers with CRS projection, plus dynamic-feature-source renderers (own-ship hull + arrowhead, AIS-target hull + per-class palette, default disc/line/polygon fallback). |
| Package | Description |
|---|---|
| EncDotNet.S100.DynamicSources.Ais | Decoder-agnostic AIS dynamic feature source: per-MMSI cache, ITU-R M.1371-aligned aging, projection to DynamicFeature with sentinel-collapsed motion. See its README. |
| EncDotNet.S100.DynamicSources.Ais.Drivers.AisStreamIo | Production driver implementing IAisMessageSource over aisstream.io's WebSocket service. BCL-only (no third-party AIS or WebSocket deps). See its README. |
| Package | Description |
|---|---|
| EncDotNet.S100.Mcp.Tools | Transport-agnostic Model Context Protocol tool surface (list_datasets, describe_feature, sample_coverage). See its README. |
| EncDotNet.S100.Mcp | Streamable HTTP host that exposes the Mcp.Tools surface plus the viewer-injected render_to_image tool; bound to 127.0.0.1 by default, off by default, no authentication. See its README and the agent walkthrough. |
dotnet buildRunning the viewer:
dotnet run --project src/EncDotNet.S100.ViewerPre-built per-platform binaries are attached to every
release.
The macOS DMG is Developer-ID signed and Apple-notarized; Windows
and Linux ship as architecture-tagged tar.gz archives.
The libraries are instrumented with Microsoft.Extensions.Logging,
System.Diagnostics.ActivitySource, and
System.Diagnostics.Metrics.Meter, and the viewer ships an
OpenTelemetry OTLP exporter configured by the standard OTEL_*
environment variables. The fastest way to see logs, traces, and
metrics is the bundled .NET Aspire host:
dotnet run --project src/EncDotNet.S100.AppHostSee docs/observability.md for the span
tree, metrics catalogue, and alternative recipes (standalone Aspire
dashboard, Jaeger).
This project is licensed under the MIT License.