Some case studies made with Houdini. Started with a simple procedural "forest" (l-systems)
It was a pretty straightforward use of the Houdini paradigm. The "trees" rotation are randomized using a generic expression that feeds on the $PT variable and its placement derives from a scatter node. The scale of each tree can be controlled using a paint node which allows painting on the viewport and acts similarly to a grayscale map in other packages, except this one is created in real time with real time feedback. It has an switch to allow to work with boxes (as proxys), so its manageable to work with high-poly trees if i want to develop a real forest scene. The ground is also procedural, with a Mountain SOP.