I'm using the Pen device at the moment but I'm trying to get the resolution better finer so I can see smoother curves.
I'm currently just using the Webots Grass appearance. Is scaling the used texture or something like that the only way to improve the lines? The Webots documentation says "The precision of the painting action mainly depends on the subdivision field of the Geometry node. A high subdivision value increases the number of polygons used to represent the geometry and thus allows a more precise texture mapping, but it will also slow down the rendering of the scene.", but I'm using a plane with the Webots Grass texture and there is no subdivision option in the geometry of a Plane.