There is a way for you to do what you want. I assemble my scenes in AutoCAD. The model is divided into layers, where each layer is made up for each texture or color to be used in Vue. You can create a very precise model this way. To position trees accurately, place vertical "sticks"or markers into the AutoCAD file. Then in Vue, you can "drop" or position each tree or bush over the marker to get accurate placement. Then export the AutoCAD scene into a 3DS file format, which imports into VUE. The idea is that you use VUE only for placing vegetation and rendering. You can even create the terrain in Vue, export to AutoCAD, then import the scene.