TFD files have so much data in them and if you simply go with default render settings you may lose out on a lot. Consider this example below. At first I was doing all sort of tricks to get my density trails to last longer then I decided to look at the viewport preview. Set it to no shader and then look at the range start and range end . These are set to 0/1 by default but just look at all that “hidden” information I got out by lowering the range end value. I could then transfer that to my final render by adjusting the density mapping.