WPF Helix how to "zoom extent" viewport3d in code?

Question

So I have this xaml code in my "view" assembly:

<helix:HelixViewport3D ZoomExtentsWhenLoaded="True"
                       ShowCoordinateSystem="True"
                       IsMoveEnabled="False"
                       Margin="5,5,5,0">
    <helix:HelixViewport3D.Camera>
        <OrthographicCamera LookDirection="1,1,-1" 
                            Position="{Binding CameraPosition}"
                            UpDirection="0,0,1">
        </OrthographicCamera>
    </helix:HelixViewport3D.Camera>
    <ModelVisual3D Content="{Binding Lights}"/>
    <local:ScatterPlotVisual3D Points="{Binding Data}"
                               SolutionPoints="{Binding Solution}"
                               SurfaceBrush="{Binding SurfaceBrush}"/>
</helix:HelixViewport3D>

in "view-model" assembly I am loading some data into ScatterPlotVisual3D which creates new plot (displaying some points, boundarybox, labels, etc):

private Model3D CreateModel()
{
    var plotModel = new Model3DGroup();
    if (Points == null && SolutionPoints == null) return plotModel;

    List<Point3D> allPoints = new List<Point3D>();

    if (Points != null && Points.Length != 0)
    {
        plotModel.Children.Add(CreatePointsModel(Points, Brushes.Green));
        allPoints.AddRange(Points);
    }

    if (SolutionPoints != null && SolutionPoints.Length != 0)
    {
        plotModel.Children.Add(CreatePointsModel(SolutionPoints, Brushes.Red));
        allPoints.AddRange(SolutionPoints);
    }

    CreateBoundaryAxis(plotModel, allPoints);            

    return plotModel;            
}

So what I need to do is force HelixViewport3D into "doing" ZoomExtents() (or any other similar way of zooming camera to fit model) when I load my data.
Problem: I cant call ZoomExtents() as I dont have any reference to helix:HelixViewport3D declared in my XAML

Answer 1

I just added event to my ScatterPlotVisual3D and assigned this event in xaml to private function of view, which has access to HelixViewport3D and calls ZoomExtents() on it. Now I call my event when I load my data