var plot = new PlotModel();

            plot.Axes.Add(new OxyPlot.Axes.CategoryAxis());
            plot.Axes.Add(new OxyPlot.Axes.CategoryAxis());

            OxyPlot.Series.ScatterSeries s;
            plot.Series.Add(s = new OxyPlot.Series.ScatterSeries());
            s.Points.Add(new ScatterPoint() { X = 1, Y = 2 });
            s.Points.Add(new ScatterPoint() { X = 3, Y = 3 });


            PngExporter png = new PngExporter();
            using (var f = File.OpenWrite("file.png"))
            {
                png.Export(plot, f);
            }