EncDotNet.S100

Overview

EncDotNet.S100 is a managed, cross-platform implementation of the IHO S-100 Universal Hydrographic Data Model for .NET. In plain terms, it reads and draws electronic nautical charts and related marine data layers — depths, currents, water levels, navigational warnings, aids to navigation, and more — and it runs on macOS, Windows, and Linux. 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.
• A standalone command-line tool (s100) that renders any supported dataset to a PNG, or to a web-map tile set, from the shell — self-contained, with no .NET install required — for batch and headless scripting.
• An optional MCP server that exposes loaded datasets to AI agents — feature discovery and query (identify_features, nearest_features, count_features, describe_feature), coverage sampling, interactive route planning, and live viewer control (drive the viewport, capture the view, steer the own-ship).

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.

Getting started

Just want to look at charts? Download the desktop viewer from the latest release — a pre-built, self-contained app for macOS, Windows, and Linux (no .NET install required) — and open a file or exchange set. The getting-started guide walks through it, and the viewer section below tours the features.

Building on top of the data? docs/getting-started.md also walks you from zero to a rendered PNG in a few minutes — via either the batteries-included EncDotNet.S100 library facade or the standalone s100 command-line tool.

using EncDotNet.S100;

using var dataset = S100Dataset.Open("chart.000");   // detects the spec
using var renderer = new PngS100DatasetRenderer();
byte[] png = await renderer.RenderAsync(dataset);     // bundled FC + PC
File.WriteAllBytes("out.png", png);

The runnable samples/EncDotNet.S100.Samples.Quickstart console project demonstrates this end-to-end against a bundled synthetic fixture — dotnet run it with no setup. The samples/EncDotNet.S100.Samples.RouteCheck checks a passage against synthetic charts, depths, water levels, areas and warnings with RouteChecker.

Supported standards

Every supported product ships a reader and a portrayal pipeline, and every product with a ✅ below ships 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-401 (IEHG)	Inland ENC	ISO 8211	Lua (Part 9A)	—
S-57 (legacy)	Electronic Navigational Charts (Ed 3.1)	ISO 8211	via S-101 pipeline

S-401 (IEHG inland ENC) shares the S-100 Part 10a ISO 8211 encoding and the Part 9A Lua portrayal model with S-101, so it is read and portrayed through the S-101 pipeline with the bundled IEHG Feature and Portrayal Catalogues (see EncDotNet.S100.Specifications/content/S401/README.md for their provenance). S-401 cells are told apart from S-101 and S-57 cells by the product identifier each declares in its ISO 8211 DSID record. Edition 1.3.0 of the S-401 Portrayal Catalogue is still a draft and no validation rule pack ships yet.

S-57 cells are translated to the in-memory S-101 model and rendered through the S-101 portrayal pipeline — or, for an inland ENC (a cell declaring DSID/PRSP = 10), through the same pipeline with the S-401 catalogues; 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.

The Viewer

SoundCharts: S-100 Viewer (project EncDotNet.S100.Viewer; website soundcharts.app) 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 a bundled offline basemap (Natural Earth land; OpenStreetMap optional). 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), Routes, Vessels (AIS targets + own-ship), Validation, and Settings — every panel can be docked, hidden, or rearranged, and the layout persists between sessions.
• Interactive route planning — build editable, persistent routes aligned to the in-repo S-421 route model: a numbered waypoint / leg timeline with per-leg great-circle or rhumb-line geometry and live distance and bearing, drawn and edited directly on the map (and drivable by an AI agent through the MCP route tools).
• Pick / Object Information for both vector and coverage products, with FC-decoded attribute names, follow-the-xlink reference 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.
• In-app feedback and crash recovery — a Report Feedback flow that bundles diagnostics into a pre-filled GitHub issue, plus next-startup detection and reporting of unclean shutdowns.
• 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 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.

Gallery

The gallery images are the soundcharts.app captures, made by site/capture/capture.cs from public NOAA and USACE data and the repo's test fixtures; manifest.json records the datasets and viewer calls behind each one.

Product	Screenshot
S-101 ENC	Quebec City harbour, from the Canadian Hydrographic Service's S-100 sample data.1
S-57 (via S-101)	NOAA ENC, Elliott Bay, Seattle.
S-57 Inland ENC	USACE inland ENC, Mississippi and Missouri at St. Louis.
S-102 Bathymetry	NOAA S-102 over the NOAA ENC, four-shade depth zones.
S-104 Water Level	NOAA S-104 water-level pilot, Charleston (repo fixture).
S-111 Surface Currents	NOAA CBOFS S-111 forecast, Chesapeake Bay entrance.
S-122 Marine Protected Areas
S-124 Navigational Warnings	Synthetic warnings (repo fixture).
S-125 Marine AtoN	S-125 derived from NOAA ENC aids to navigation, Elliott Bay.
S-127 Marine Services
S-128 Catalogue
S-129 UKC	UKC plan, Torres Strait (repo fixture).
S-131 Marine Harbour	S-131 derived from NOAA ENC harbour features, Elliott Bay.
S-411 Sea Ice	US National Weather Service ice analysis, Alaska.
S-421 Route Plan	Route plan, Baltic (repo fixture).

1 The S-101 chart of Quebec City was made by the EncDotNet.S100 project and contains intellectual property of the Canadian Hydrographic Service (CHS) of the Department of Fisheries and Oceans. This product does not meet the requirements of the Navigation Safety Regulations, 2020 under the Canada Shipping Act, 2001. Charts and publications issued by or on the authority of CHS must be used to meet the requirements of those regulations. The copyright in the data are and remain the property of His Majesty the King in Right of Canada and shall not be sold, licensed, leased, assigned or given to a third party. The incorporation of CHS data in this product does not constitute an endorsement or an approval of this product by the Canadian Hydrographic Service, the Department of Fisheries and Oceans or His Majesty the King in Right of Canada.

Command-line tool

s100 is a cross-platform console tool that renders any supported product to a PNG, JPEG, or WebP from the shell — and validates datasets and exchange sets against the normative rule packs — driving the same portrayal and validation pipelines as the viewer through a headless Skia renderer, no UI required. It is suited to batch and scripted previews (sea-ice, surface-current, and chart thumbnails) and to CI conformance checks.

s100 render dataset.h5 out.png --palette night -w 2048 -h 1536
s100 validate exchange-set/    # normative rules + exchange-set integrity
s100 info dataset.h5           # detected spec, edition, and time steps
s100 list-specs                # supported products

Each release attaches a self-contained, per-platform archive that bundles the .NET runtime and native libraries, so no .NET installation is required — download, extract, and run. The same executable also ships inside the viewer application bundle. See docs/cli.md for the full command and option reference.

Libraries

For developers consuming EncDotNet.S100 directly, the solution is split into focused packages.

Convenience facade

Package	Description
EncDotNet.S100	Batteries-included on-ramp: open a dataset, read its features, and render it to an image using the bundled feature and portrayal catalogues — no hand-wiring of catalogues or pipelines. Start here; drop down to the focused packages below only when you need finer control.

Core framework

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, with signature/checksum integrity verification and S-100 Part 15 data-protection (decryption) support.
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.

Encoding and scripting backends

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.
EncDotNet.S100.Crs.ProjNet	CRS transform backend (ICrsTransformFactory) using ProjNet — WGS84 UTM zones and EPSG:4326 ↔ EPSG:3857. Mapsui-free, so headless consumers (the facade and the s100 CLI) can reproject coverage products without linking a map renderer.

Product datasets

Package	Description
EncDotNet.S100.Datasets.S101	S-101 ENC reader (incl. sequential updates), 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 of status indications plus AtoN symbology via the S-101 Lua rules, 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.

Navigation

Package	Description
EncDotNet.S100.Navigation	Leg ETAs and an under-keel clearance check along a route: charted depth (S-102, S-101 fallback) plus S-104 water level, minus draft and squat, at each sample's ETA. Depends only on Core.
EncDotNet.S100.Routes.Rtz	RTZ route plan reader and writer (IEC 61174 Annex S, versions 1.0, 1.1 and 1.2), keeping unknown attributes and vendor extensions for round trips. Depends only on Core.

The EncDotNet.S100.Datasets.S129.Fusion library (project reference, not published to NuGet) is a purely additive cross-product helper that fuses an S-129 under-keel-clearance plan with the typed S-102, S-104, and S-421 datasets it references and exposes a time-indexed view over the plan.

Renderers

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).

Dynamic feature sources

These ship in the repository but are not currently published to NuGet — consume them via project reference (or through the viewer).

Project	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.
EncDotNet.S100.DynamicSources.Ndbc	NOAA NDBC buoy and C-MAN observations as a dynamic feature source: station table, realtime2 parser, viewport-gated polling with backoff and ageing, and a station-model glyph (wind barb and wave height) built with the portrayal toolkit. Not for navigation. See its README.
EncDotNet.S100.DynamicSources.Nmea	Own-ship wind, water and air temperature and pressure from NMEA 0183 as a dynamic feature source: true wind from MWD or derived from apparent wind and the vessel's motion, drawn as a wind barb next to own ship; relative wind labelled as such. Not for navigation. See its README.
EncDotNet.S100.Nmea	Minimal NMEA 0183 reader: checksums, talker-agnostic MWV, MWD, MTW, XDR, HDT, HDG, VHW, RMC and VTG, true wind from apparent, and stream, replay-file, TCP and UDP line sources. See its README.

MCP server

These ship in the repository but are not currently published to NuGet — consume them via project reference (or through the viewer).

Project	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.

Building

dotnet build

Running the viewer:

dotnet run --project src/EncDotNet.S100.Viewer

Pre-built per-platform binaries are attached to every release. The macOS DMG is Developer-ID signed and Apple-notarized; the Windows .exe is Authenticode-signed via Azure Trusted Signing. Windows ships as architecture-tagged zip archives and Linux as architecture-tagged tar.gz archives. The standalone s100 command-line tool is also attached per platform as s100-<version>-<rid> (.zip on Windows, .tar.gz on macOS/Linux); see docs/cli.md for install instructions.

Observability

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.AppHost

See docs/observability.md for the span tree, metrics catalogue, and alternative recipes (standalone Aspire dashboard, Jaeger).

License

This project is licensed under the MIT License.