The charts are based on HTML5/SVG and VML for older IE versions. All charts are interactive, and some are pannable/zoomable as well. You can take a look at their extensive chart gallery here .

A donut chart with a single point is rendered in SVG as a circle the size of the empty space. This is OK with a standard pie chart, and OK in PNG. ScottPlot Version: (What NuGet package are you using?