Open source is a broad concept and used in many program to a varying degree. Some programs let's you see the entire code and others give user pathways to add features via DLL's etc.. Take a look at Max for example. The DLL system there lets you augment many important things in the program. You can write your own renderer for example. I believe this is a key feature for Max's success. The third party business can augment a lot in Max. Many times I've wished Bryce had some sort of documented add-on hook. A side note on a previous message (#12) about how many polys were used in "Dungeons and Dragons". I dug up the january issue of 3D World and it it says that the dragons used about 80,000 polys or less. It goes on to say that they used four months of round-the-clock render-farming for a 10-15 minutes CGI sequence. I wonder what the pixel height and width was for each picture.