Matching Motion Blur with Timewarp

[Conorflan]

Hi all,

Maybe I've misunderstood the documentation around Timewarp and the warp layer, but...

What i want to do is use the motion information from my plate to apply motion blur to an element on another layer.

What I've done is.

Apply Timewarp to additional element

Set  Speed to 100

Enabled Motion blur.

and  set the warp layer to the plate. (I've also precomped the plate as suggested in the documentation)

Now, what happens next appears to be a bug as it's not expected at all.

My Plate layer seems to override the Element layer, even when the plate is turned off or the element is solo'd.

The motion blur is applied but the output is the wrong layer.

Anybody have any ideas?

Cheers.

[Rick Gerard]

Without seeing the modified properties of the layers you are having problems with it's pretty difficult to guess. Pressing U twice reveals everything that is modified.

What I usually do to match motion blur is to enable it in the comp and the preview panel, apply CC force motion blur to the layer I need to match and make the adjustments there. You may need to pre-compose the layers to get them to match.

If that doesn't do it please attach a screenshot.

[Conorflan]

Hi Rick,

Thanks for the speedy reply, I was just mocking up something to better illustrate my point.

Am I wrong in assuming that Motion Blur should be applied to the Element?

The element layer isn't invisible, as may be interpreted from the below, but is instead filled with the Plate layer (with Pixel Motion Blur on it).

[Conorflan]

And "Enable Motion Blur" is checked.... I just stupidly didn't include it in the screen, and shutter is set to manual and 180.

[Conorflan]

Hi Rick I've updated it with screens below.

I also went back to cs6 and im getting the same behaviour.

Although I see the plugin is v1.0 throughout.

We're now looking at getting RSMB but it is an expensive solution as we've 10 compers and further 40render nodes.

From the documentation this should do what we need.

Pixel motion blur is out because it adds motion blur to the blinks also, which creates nasty artifacts.

We just need blur from the characters motion.

any 2 cents are appreciated.

[Kevin-Monahan]

Hi Conorflan,

Did you ever solve this issue? Did you try Rick's suggestion of CC Force Motion Blur? Or something else? If so, what was it? Sorry if you couldn't solve this issue natively.

Thanks,
Kevin

[Conorflan]

Sadly not.

CC force motion blur doesn't detect motion on a plate. Pixel motion blur is close to what we want but the artifacts are nasty when dealing with two directions, ie. a left/right camera move and a blink.

Timewarp, by the documentation should do what we want. Detect motion from a referenced plate and apply it to the layer the effect is applied to. This isn't the case.

"Warp Layer Allows you to warp the layer to which the effect is applied by applying the motion vectors from the layer that you choose." from Using time effects in After Effects

When the warp layer is selected (in this case our back plate), then the layer on which the effect is applied looks like that layer.

We've gone with buying RSMB - which is awesome and we can instead use motion vectors to get it to look great. But it adds time to the pipeline, and we now have our Nuke guys looking all different kinds of smug

But I believe Timewarp is bugged with regards the warp layer.

[Dave_LaRonde]

You need to ANIMATE the force motion blur effect.  With keyframes.

[Conorflan]

i understand how force motion blur works compared with pixel motion blur.

I'm trying to avoid the nasty articfacts that come from the algorithm being confused between two different vectors.

By the documention timewarp should let me apply the motion of one plate on to another.

But instead the effect just copies the rgb values of the target warp layer and replaces them on the layer the effect is applied.

Now, this method means we're loosing motion blur on the blink. But after some tests in nuke it didn't look too bad.

if I've misunderstood the documentation regarding timewarp, which I've read others doing regarding motion vector passes, please enlighten me. But timewarp seems to be bugged in this regard as the behaviour isnt even close to expected.

As I said we've gone with the extra spend with rsmb licenses as production can't stop.

But it would be nice to get this issue around timewarp addressed. Either the documentation or the plugin.

[Kevin-Monahan]

Hi Conorflan,

You can file a bug here. Sorry for the frustration.

Regards,

Kevin