I'm keen on methods of rendering trees in real time. One I hadn't come across before is described in a paper titled Rendering Forest Scenes in Real-Time by Philippe Decaudin, Fabrice Neyret, Florent Cohen. It's volume texture based; a terrain is extruded into prisms, and a volume cell is rendered through ray tracing. The prisms themselves contain data that matches up for aperiodic tiling. A bit of raymarching, lighting, shadow casting, and a nice (if kind of regular looking) forest is the result. I suppose this technique can only be used for middle to distant trees, or in applications like real time strategy games that benefit from an orthographic perspective. Nonetheless, it's a nice addition to the body of tree rendering methods.