SciChart features a rich PointMarkers API to annotate the data-points of certain series with markers, e.g. Ellipse, Square, Triangle, Cross or custom  (UIElement) marker:

There is a whole lot of articles about the PointMarkers API available in our documentation. Please find the most relevant of them listed below:

• PointMarkers API - describes the API in general and different kinds of Point Markers
• Scatter-Line Series Type - explains how to add Point Markers to a Line Series Chart
• Scatter Series Type - shows how to create a Scatter Series Chart
• Extreme Scatter Series Type - special series type which is designed for the fastest rendering of colored Scatter Series Chart.

There is also a set of related examples in SciChart Examples Suite. Their source code can be found online at the links below:

• Using Point Markers
• Scatter Chart Demo
• Line and Scatter Chart
• Realtime Scatter Chart Demo
• Scatter Chart Performance Demo

Also Point Markers can be plotted on a Polar Chart, Ternary Chart and Radar Chart. All relevant information about these can be found in corresponding documentation articles.