Ummm why not just do all this in the VTT? Of course, I don't know most VTT's but many allow dropping objects(trees, rocks, tables,etc) that are already created as png files directly onto the map and move/size as needed.

One note though..if you are using a VTT for internet play, I would highly suggest down sizing the images OUTSIDE the VTT since most Dundjinni images are are very large(200 pixels per inch) and you want to try to make images a bit smaller(100 or 50 pixels per inch) in an outside program.... first.