I have some particles emitting from geometry and using attributes from a texture to control emission and particle color.
Here's a quick test I made a while back as a proof of concept.
https://vimeo.com/185490836 [vimeo.com]
I have finished doing the simulations on the final project and I'm tweaking the shader and render properties. I noticed I get the best motion blur by using both velocity and acceleration. It produces curved motion blur instead of linear.
But I noticed something weird and want to understand what is producing it. When I turn motion blur off the particles leave a sort of dust trail behind them and have varying opacity. When I turn motion blur on the trails disappear and they all go back to 100% opacity. I will render with motion blur so it's not necessarily a problem but I don't understand what is causing this behaviour.
I've attached 2 images. One with and without motion blur. I made the particles really big and put a camera on top to illustrate my point.
All simulations have been cached and saved to disk but I have not yet made a final bgeo export to get rid of subsamples. Also quick question: are subsamples needed for good motion blur if I'm using velocity and acceleration?