Cartographie SqlGeography avec Dapper

J'ai l'entité "Point", qui contient les coordonnées Id, Text et geography.

CREATE TABLE [Point] (
    [Id] INT IDENTITY CONSTRAINT [PK_Point_Id] PRIMARY KEY,
    [Coords] GEOGRAPHY NOT NULL,
    [Text] NVARCHAR(32) NOT NULL,
    [CreationDate] DATETIME NOT NULL,
    [IsDeleted] BIT NOT NULL DEFAULT(0)
)

CREATE PROCEDURE [InsertPoint]
    @text NVARCHAR(MAX),
    @coords GEOGRAPHY
AS BEGIN
    INSERT INTO [Point](Text, Coords, CreationDate)
    VALUES(@text, @coords, GETUTCDATE())    
    SELECT * FROM [Point] WHERE [Id] = SCOPE_IDENTITY()
END

C'est le code SQL de la table et la procédure stockée d'insertion. J'ai classe pour utiliser dapper:

public class DapperRequester : IDisposable {
    private readonly SqlConnection _connection;
    private SqlTransaction _transaction;

    public DapperRequester(string connectionString) {
        _connection = new SqlConnection(connectionString);
        _connection.Open();
    }
    public void Dispose() {
        _connection.Close();
    }

    public void BeginTransaction() {
        _transaction = _connection.BeginTransaction();
    }
    public void CommitTransaction() {
        _transaction.Commit();
    }
    public void RollbackTransaction() {
        _transaction.Rollback();
    }

    public void Query(string query, object parameters = null) {
        Dapper.SqlMapper.Execute(_connection, query, parameters, transaction: _transaction);
    }

    public void QueryProc(string procName, object parameters = null) {
        Dapper.SqlMapper.Execute(_connection, procName, parameters, commandType: CommandType.StoredProcedure, transaction: _transaction);
    }

    public IEnumerable<T> Execute<T>(string query, object parameters = null) {
        return Dapper.SqlMapper.Query<T>(_connection, query, parameters, transaction: _transaction);
    }

    public IEnumerable<dynamic> ExecuteProc(string procName, object parameters = null) {
        return Dapper.SqlMapper.Query(_connection, procName, parameters,
                                         commandType: CommandType.StoredProcedure, transaction: _transaction);
    }

    public IEnumerable<T> ExecuteProc<T>(string procName, object parameters = null) {
        return Dapper.SqlMapper.Query<T>(_connection, procName, parameters,
                                         commandType: CommandType.StoredProcedure, transaction: _transaction);
    }
}

La classe c # est:

public class Point
{
    public int Id { get; set; }
    public SqlGeography Coords { get; set; }
    public string Text { get; set; }
}

Et dépôt a méthode

public Point InsertPoint(string text, SqlGeography coords)
    {
        using (var requester = GetRequester())
        {
            return requester.ExecuteProc<Point>("InsertPoint", new { text, coords }).FirstOrDefault();
        }
    }

Quand j'utilise un tel système pour n'importe quelle autre classe, tout va bien, mais il y a un problème de mappage, je pense que c'est à cause du type SqlGeography.

SqlGeography coords = new SqlGeography();
        coords = SqlGeography.Point(10.5, 15.5, 4326);
        Point point = new Point { Coords = coords, Text = "Text" };
        point = Repositories.PointRepository.InsertPoint(point.Text, point.Coords);

Et j'ai une exception The member coords of type Microsoft.SqlServer.Types.SqlGeography cannot be used as a parameter value

Y a-t-il un secret de cartographie de ce type?