View Full Version : Motion blur on propellors

01-02-2004, 05:52 AM
Hi there,

We have a Lightwave model of a Spitfire which when animated in a sky environment does'nt look correct as the props do not have a proper motion blur. We have tried increasing the motion blur settings and revs but it still looks bad. Is there anything that we're missing here?



01-02-2004, 10:04 AM
Make sure your anti-aliasing setting is up high enough. (like at least medium)

01-02-2004, 02:27 PM
Do a search here, google, cgtalk, everywhere!
I remember seeing a tutorial on proper propeller propulsion!
:) say that 10 times fast!

01-02-2004, 05:07 PM
Have you tried Vector Blur ?? (Image filter plugin)

01-02-2004, 06:03 PM
Just increasing the revs won't make an awful lot of difference since a blade only has to rotate 120 degrees to have the next blade in the same position as the one before it.

So - work in multiples of 120 to start with (obviously a 4 bladed prop is going to be 90 degrees)

A blade rotated 120 or 122 degrees over 2 frames - given a 30fps setup works quite well. 122 degrees gives that slightly more interesting slow strobing effect, but still leaves the prop looking as if it is spinning very fast. In fact it is going at 1830 rpm which is quite slow for a merlin, but if you made it real, the blades would be a solid blurry disc.

As previously mentioned - motion blur set at leat 50% if not higher, at least Enhanced Low a-a.

15% to 20% High Quality Vector blur (with Vector type selected) - but not too high, since it can give a bad effect on the trailing edges on wings etc if you move the aircraft.

You'll need to experiment with that a bit depending on the relative movement.

Other things to try are broad fan shaped blades on the spinning prop (if it has to be shown starting up, you can morph it). Make these about 300% broader at the tip compared to the root, and half your motion blurring is done for you.

Maybe consider a simple quad with an alpha texture of a blurry fan shaped prop - spin that at the same speed & don't bother with motion blur, vector blur etc. V fast to render, but don't try to view it side on.

You can of course combine a real prop, and a spinning disk (as long as they spin together).

01-03-2004, 03:58 AM
I remember a similar discussion from way back on the old forum.

Try this link


01-03-2004, 04:08 AM
Parent the blades to a 'spin' null, rotate the blades just enough to get the blur length you want, do that back and forth, then slowly rotate the 'spin' null.

01-03-2004, 09:06 AM
yeah, i think remember that tutorial, or that discussion. i remember that small important piece of advice though: dont make the blades go faster. make them go slower so that the motion blur can 'smear' it more evenly, if you catch my meaning.