The Project menu contains items which apply to a project generally.
Render Current Render Node: This item starts a render using the current render node. The current render node is the one which has its Master checkbox checked.
Bake Animation Curves: This item modifies all animation curves by inserting a key frame at every frame. One use of this is for exporting animation data to use in other applications. Having key frames at every frame ensures that there are no differences in the animation data due to differing key frame interpolation methods in different applications.
Please note that the Bake Animation Curves item is only available if you have the Deep with Animation version of TG2.
Show Project Assets: This item opens the Project Assets window, which shows all the assets such as object files or image files used in the project.
Purge Undo: This item will dispose of all undo operations. You might want to do this if you want to free up the memory used before starting a render. The menu item also shows how much memory in megabytes (MB) is currently being used to store the undo operations.
Purging Undo will mean you're not able to undo changes made previously. In most cases you will find that the memory being used is only a small amount so it's probably not worth purging it.
A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.