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# Wheels, motion blur and motion vectors

I think this can give you some ideas. It’s interesting. Im not sure how I would go about using it do decrease blur, but none the less it’s extremely useful info for rotating objects.

You can move wheel rotation to vertex shader, instead of doing it as an object. That adds certain difficulties, such as complications with normal maps and added shader costs, however it also opens you a way to precisely control how much rotational blur you get independently from rotation speed using previous frame switch. I’m using this technique for fast rotating gears and generally it can be applied to wheels. Here are comparison shots for a cog, doing 12 revolutions per second:

Default blur:

https://image.prntscr.com/image/FIEFIxi7Rf2DrpF3XX-wFQ.png

WPO rotation, with 0.02 revolution lag for previous frame:

https://image.prntscr.com/image/HksWZkmzSxeoJqjuMotQuw.png

WPO rotation, with 0.005 revolution lag for previous frame:

https://image.prntscr.com/image/BSVVdn4IQ-6htZCUCjB3Tw.png

You could do this with a custom shader written in USF to modify the motion vectors. In Epics Demo, they used a Radial Blur Cage.

Someone needs to prod Zak Parish and @AlanNoon about how they did this: https://twitter.com/AlanNoon/status/868111915406544896

I need this a lot

Hi,
Would it be possible for You to elaborate on Your solution? More specifically I’m talking about the material setup You have for the motion blur applied here.

how did you change the speed of the tires? i don’t see any way to slow them down?

You can have two sets of tires, hide the original ones and use them as dummies to control the visible ones. Then you can take the velocity and halve that.

That being said, while @Deathrey 's solution is very clever and produces very nice results, it’s pretty expensive.

So any news on how they did this? https://twitter.com/AlanNoon/status/868111915406544896

Hi,AlexGorcea. It seems you have got a solution for it. I also tried to do with WPO rotation but still didn’t how it really works. Could you share more information about your solution or shader graph?

I have the models and textures but I don’t know how to use them yet because I’m beginners, what is this function called? What do you recommend me to ask or look for to effect this effect?

still nothing is known?

Epic’s technique is included in the Content Examples pack. Read the documentation.