Motion Blur compensation on lightsaber blade?

Hey all, long time no see.

Recently I decided to dick around with the lightsaber FX and put one of my prop builds through the motions.

While I was making this video, I noticed that the saber blade (a PVC pipe) was blurring really wide during the swings, which the Lightsword effect's interpolation doesn't cover, even if you play with the persistence settings.  You can't really see it in the final video, but I was wondering if anyone knows a good way to cover it up.  Would using a thinner blade on the prop help?  Is there an effect setting I am overlooking?




  • Would not a filming using a higher shutter speed produce less motion blur with your PCV tube?  This is similar to the recommendation of using a higher shutter speed when filming something that will be  chroma keyed  to avoid motion blur.

  • Triem23Triem23 Moderator

    Also, are you using two point or four point Lightsword? 4 point has a lot more control. 

    Even WITH a Lightsword effect lightsabers require manual finessing. The entire reason those blades get so wide on fast moves was the roto artist painting out the motion blur on the prop to begin with. 

  • @BobDiMarzio probably, but I shot this footage on my phone.  Thanks for reminding me, though.  I should definitely look into that for the future.

    @Triem23 I was using the 2-point.  It occurred to me later that the 4-point might have been a better choice for precisely that reason.  Can you expand on that bit about painting out the motion blur?

  • Steve,

    I would take a look at this Hitfilm video by Simon Jones. Especially pay attention to what he talks about starting at 10:35 minutes in. This should take care of you!

  • Triem23Triem23 Moderator

    Steve, remember the original trilogy was hand airbrushed roto, so with tge fanning of the blades, it was literally the artist painting over motion blur. :-) for the prequels sabers would have  been hand roto of a white planar solid, so, again, literally painting over the motion blur. 

    Incidentally, way back on the Hitfilm channel is an old Axel tutorial, predating Hitfilm's Lightsword effect, on old-school plane roto. 

    I think the two-point lightsaber effect is great for slow moving sabers, but the four-point is way better for fast motion, since you have much more control over the spread of the blade. The motion blur on the two-point doesn't look correct to me. Remember, you can combine both effects on a single layer by keyframing the extension to swap effects (dial one to zero, one to one hundred as needed). For slow movement's, use two points and follow the leading edge (ignoring the other two points), then for fast moves you can then adjust the back edge points. To me this is the best compromise between the ease of two-point and the control of four-point. 

  • Steve,

    Last year, I made an entire series (20 video tutorials) on how to create a light saber battle from beginning to end in Hitfilm Express. This was before the Light Sword Effect was available, but the principles of painting the blade are the same. Feel free to check it out if you like, especially Episodes 9-13 cover how to paint the blade in detail. Good luck and fun!

  • edited June 2017

    Thanks guys!  And hm, yeah apparently I forgot to uncheck the Auto Scale parameter before using Motion Persistence.

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