I love 3D and practically everything that has to do with it especially Open Source software that is regularly developed. My current favorite OS software is appleseed (https://appleseedhq.net/). The recent beta release is quite feature rich with the 3ds Max DCC coming along very well (Max is my main modeling tool).  Volumes were added to the Max plugin and I just had to play with it. So, here is a scene built to test out a foggy environment using the volume material in appleseed-max. There are no materials other than grey scale so the engine has something besides the color of the models to work with. I will be working with this scene over time to see how far I can push the volumes material.