Table of Contents

Getting started

In this quickstart you add EncDotNet.S57 to a console app, read an S-57 cell, and list its depth areas with their depth ranges and positions.

Prerequisites

Create a project

dotnet new console -o EncQuickstart
cd EncQuickstart
dotnet add package EncDotNet.S57

EncDotNet.S57 brings in EncDotNet.Iso8211, which decodes the ISO/IEC 8211 container that S-57 cells use.

Read a cell

Replace the contents of Program.cs:

using EncDotNet.S57;

S57Document document = S57DocumentReader.ReadFromFile("path/to/cell.000");

Console.WriteLine($"Cell:    {document.DataSetIdentification?.DataSetName}");
Console.WriteLine($"Edition: {document.DataSetIdentification?.EditionNumber}");
Console.WriteLine($"Scale:   1:{document.DataSetParameters?.CompilationScale}");
Console.WriteLine($"{document.FeatureRecords.Count} feature records, {document.VectorRecords.Count} vector records");

Run it:

dotnet run

You see the cell name from its DSID field, the edition, the compilation scale from DSPM, and the record counts.

List the depth areas

Each feature record has an object class (OBJL), such as DEPARE for a depth area, and a list of attributes. Attributes are identified by their numeric code from the S-57 attribute catalogue: DRVAL1 (87) and DRVAL2 (88) hold the shallow and deep limits of a depth area.

Add this to the end of Program.cs:

const int Drval1 = 87;
const int Drval2 = 88;

foreach (S57FeatureRecord feature in document.GetFeaturesByObjectCode(S57ObjectCode.DEPARE))
{
    string? shallow = feature.Attributes.FirstOrDefault(a => a.AttributeCode == Drval1).Value;
    string? deep = feature.Attributes.FirstOrDefault(a => a.AttributeCode == Drval2).Value;

    Console.WriteLine($"{feature.RecordName}: {shallow} to {deep}");
}

Run it again. Each line names a depth area record and its depth range, in the units the cell declares in DSPM (usually metres).

Get positions

Coordinates are stored as integers. Divide them by the coordinate multiplication factor (COMF), or let ToDecimalDegrees do it. A feature points to its geometry through spatial pointers (FSPT). This prints the first stored coordinate of each vector record the first five depth areas point to:

int comf = document.CoordinateMultiplicationFactor;

foreach (S57FeatureRecord feature in document.GetFeaturesByObjectCode(S57ObjectCode.DEPARE).Take(5))
{
    foreach (S57SpatialPointer pointer in feature.SpatialPointers)
    {
        S57VectorRecord? vector = document.GetVectorRecord(pointer.Name);
        if (vector is null || vector.Coordinates2D.Count == 0)
        {
            continue;
        }

        var (longitude, latitude) = vector.Coordinates2D[0].ToDecimalDegrees(comf);
        Console.WriteLine($"{feature.RecordName} -> {pointer.Name}: {latitude:F6}, {longitude:F6}");
    }
}

Next steps

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