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, and rendering 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 and renders them, time-aligned, on an interactive map.
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.
| Standard | Subject | Encoding | Portrayal |
|---|---|---|---|
| S-101 | Electronic Navigational Charts | ISO 8211 | Lua (Part 9A) |
| S-102 | Bathymetric Surfaces | HDF5 | Coverage |
| S-104 | Water Level Information | HDF5 | Coverage |
| S-111 | Surface Currents | HDF5 | Coverage + arrows |
| 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 |
S-57 cells are translated to the in-memory S-101 model so they render through the S-101 portrayal pipeline. 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 of the supported product
types — individually or together — and renders them on an interactive
map with a basemap underlay.
Loaded datasets appear in the Datasets panel on the left. Each entry has an inline visibility toggle and up / down buttons that reorder the paint stack. Selecting an entry reveals a Properties sub-panel with two tabs:
- Dataset — high-level information (product spec, current timestamp for time-varying datasets, loader status) and a whole-dataset opacity slider.
- Layers — per-sub-layer visibility and opacity for products that paint more than one layer (currently S-111, which has both a colour-band layer and an arrow layer).
A small toolbar above the list offers bulk Show all, Hide all, Isolate selected, and Reset opacity actions.
Standard ECDIS controls are available from the View menu:
- Display category (Base / Standard / Other) filtering for S-101.
- Display plane toggles to show or hide entire feature planes.
- Text group toggles for quickly suppressing or revealing labels.
- Per-spec viewing group overrides for fine-grained control.
Picking is performed in an ECDIS-style Pick Mode: toggle the
cross-hair button on the map toolbar (or View → Appearance → Pick
Mode, or press I) and then click any feature to open the
Object Information panel on the right — a "pick report" showing
the feature's class, identifier, source dataset, and full attribute
list. Press Esc to leave Pick Mode.
On macOS, Cmd-click (and Ctrl-click on Windows / Linux) acts as a one-shot pick regardless of mode. A press-and-hold of about half a second on any map location is also treated as a one-shot pick.
Attribute names and enumerated values are decoded against the
product's feature catalogue — codes like CATPLE are shown as
"Category of pile", and enum integers are shown with their
human-readable labels. xlink:href references to other features
(heavily used by S-125 AtoN status bindings and S-421 route
topology) appear under a References section; clicking a row
jumps the pick report to the referenced object.
Pick reports work for both vector products and coverage products — clicking a coverage chart samples the underlying grid at the click location and reports the per-cell value (depth + uncertainty for S-102, water level + trend for S-104, current speed + direction for S-111).
A Search field above the Datasets panel finds any feature across every loaded dataset in a single keystroke. Type a feature class, a human-readable name, or an identifier and pick a result to jump straight to it in the Object Information panel. Equally happy with a curated single-cell load or a folder full of overlapping exchange sets.
S-104 water levels, S-111 surface currents, and S-411 sea-ice information all carry timestamps. When one or more of these is loaded, a global timeline appears at the bottom of the map and aggregates every time sample across the loaded datasets into a single slider.
Drag the thumb to scrub time; every participating dataset is re-rendered at the snapped sample. When all loaded datasets share the same set of timestamps the slider shows discrete stops at each one, plus previous / next buttons for single-step navigation; otherwise it falls back to evenly-spaced guide ticks across the aggregate range. The panel can be hidden from View → Appearance → Timeline.
The viewer rendering each supported product:
Vector chart data with IHO symbology including depth contours, navigation aids, land areas, and other chart features.
Colour-shaded bathymetric depth grids providing high-resolution seafloor elevation data.
Gridded water level data for surface navigation, showing tidal and non-tidal water level variations.
Gridded surface current data with both a colour-band layer and a directional-arrow overlay.
UK MPAs around the Solent and Isle of Wight from the UKHO trial dataset.
Navigational warnings highlighting hazards and notices to mariners.
Lights, buoys, beacons, daymarks, and AIS aids, including AtoN status indication symbology.
Pilot boarding places, routeing measures, restricted areas, vessel
traffic services, and signal stations rendered via XSLT portrayal.
Shown above: the official IHO sample 127JS00EX_A0001.GML.
The official IHO 2.0.0 sample dataset covering East Asia: electronic products (yellow), physical products (green), and S-100 services (magenta) as semi-transparent coverage areas.
Under keel clearance data for safe navigation in shallow or restricted waterways.
Berths, bollards, mooring buoys, anchorage areas, and terminals — the first GML+Lua hybrid in this codebase.
Sea-ice and lake-ice information: concentration, stage of development, ice edges, and icebergs.
Waypoints, route legs, and action points along a planned voyage.
NOAA chart US4FL1LT.000 (Caloosahatchee River, FL) — 1,889
features translated to S-101 producing 3,640 portrayal drawing
instructions. Per-feature mappings follow the IHO S-57 to S-101
Conversion Guidance document. Not an S-52 implementation.
For developers consuming EncDotNet.S100 directly, the solution is split into focused packages:
| Package | Description |
|---|---|
| EncDotNet.S100.Core | Core abstractions and pipeline framework (asset sources, HDF5, Lua scripting, coverage and vector pipelines). |
| 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 and Lua portrayal pipeline. |
| EncDotNet.S100.Datasets.S102 | S-102 bathymetric surface reader and coverage pipeline. |
| EncDotNet.S100.Datasets.S104 | S-104 water level reader and coverage pipeline. |
| EncDotNet.S100.Datasets.S111 | S-111 surface current reader and coverage pipeline. |
| EncDotNet.S100.Datasets.S122 | S-122 marine protected areas reader and XSLT portrayal pipeline. |
| EncDotNet.S100.Datasets.S124 | S-124 navigational warnings reader and XSLT portrayal pipeline. |
| EncDotNet.S100.Datasets.S125 | S-125 marine aids to navigation reader, strongly-typed DataModel projection (with xlink-resolved AtoN status), and XSLT portrayal pipeline. |
| EncDotNet.S100.Datasets.S127 | S-127 marine resources and services reader and XSLT portrayal pipeline. |
| EncDotNet.S100.Datasets.S128 | S-128 catalogue of nautical products reader, XSLT portrayal pipeline, and typed DataModel projection with resolved supersedes navigation. |
| EncDotNet.S100.Datasets.S129 | S-129 under keel clearance reader and XSLT portrayal pipeline. |
| EncDotNet.S100.Datasets.S131 | S-131 marine harbour infrastructure reader and Lua portrayal pipeline (GML+Lua hybrid). |
| EncDotNet.S100.Datasets.S201 | S-201 aids to navigation information (IALA, authority-to-authority exchange) reader, XSLT portrayal pipeline, and strongly-typed AtoN inventory data model. |
| EncDotNet.S100.Datasets.S411 | S-411 sea ice reader and XSLT portrayal pipeline. |
| EncDotNet.S100.Datasets.S421 | S-421 route plan reader and XSLT portrayal pipeline. |
| EncDotNet.S100.Datasets.S57 | Legacy S-57 ENC reader that translates to the in-memory S-101 model. |
| 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. |
| Package | Description |
|---|---|
| EncDotNet.S100.Mcp.Tools | Foundation for a Model Context Protocol server: IDatasetCatalog abstraction and the tool surface (list_datasets, describe_feature, sample_coverage). Transport-agnostic. See its README. |
| EncDotNet.S100.Mcp | Streamable HTTP MCP server that exposes the Mcp.Tools surface. UI-agnostic; bound to 127.0.0.1 by default, off by default, no authentication. The viewer hosts this opt-in; see its README and the agent walkthrough. |
dotnet buildRunning the viewer:
dotnet run --project src/EncDotNet.S100.ViewerThe 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.AppHostThis starts the Aspire dashboard and the viewer in one step — open the
printed http://localhost:15069/login?t=… URL to inspect them. See
docs/observability.md for the span tree,
metrics catalogue, and alternative recipes (standalone Aspire
dashboard, Jaeger).
Scripted performance scenarios for profiling pipeline, portrayal, and rendering costs:
# Run a scenario
dotnet run --project tools/EncDotNet.S100.PerfRunner -- s124-vector
# Summarise a run
dotnet run --project tools/EncDotNet.S100.PerfReport -- summarise perf-runs/<file>.jsonl
# Diff two runs
dotnet run --project tools/EncDotNet.S100.PerfReport -- diff baseline.jsonl candidate.jsonlSee PerfRunner README and PerfReport README for details.
This project is licensed under the MIT License.